Understanding Formation Evaluation Techniques

okay uh let me start uh just saying good morning good afternoon and good evening wherever you are my name is mustafa orby i'm the graduate program director and also a professor of the petroleum engineering at the american university in cairo i've been with the industry for almost 25 years finally i need to pay back some some some part of my experiences to the academia that's why i'm joining the the american university in china okay today actually i will start talking about the formation evaluation not from just the tools point of view we covered this in the previous lectures so if you need to go and back and refresh your memory on tools and two responses and what are the design of each tool what each tool actually measures in this case you need to i will refer you back to some of the uh petrol and the arab oil and gas academy database that you can actually go and watch this video today i will assume that you guys know these login tools so how can we use we combine all these tools to come up with a very quick look well notice when i say quick look because there are actually two different type of analysis something that we do very quickly especially if the if the rig is waiting on our decision uh will we continue completing this zone uh this one is our potential zone or not uh how can we define this out with a very quick evaluation then we go for complex uh well analysis that goes back after you go back to the office and you start doing in-depth analysis of the logging data and also you share this with the geogeologists the geophysicist to come up with a broader understanding of the geological and the structure of your of your reservoir that goes for the reservoir characterization and the structure but for the very quick evaluation of do we really need to complete this zone or not uh is this well and i would put in a good place or not what is a pays on how big is the pay zone uh how much porosity do i have these type of things which is a very quick thing that that will help us make a good decision okay so with that said let me start with saying basic wire line logging data that we all use when i say why online because we covered here in this webinars and the previous webinars only the wire line logging data there are also loading while drilling equipment and tools that we can use they deliver similar measurements with some differences based on the environment that each of these tools actually are run in so in this case there are some differences between them but for the time being we're talking about the wire line logging this means the drilling is over no drilling it's only the wire line using the one line cable we acquire certain type of data okay the first one is the the borehole caliper oral caliper is the one that we actually use to find out what is the borehole size what is the diameter of the borehole at every depth why do we need to do to know that we'll talk about this in a minute so we have a tool that measures the borehole they enter at every depth that every measurement we do one of the measurements is is abort or damp we do this with a character then we run another two which is called the gamma ray to either total gamma ray tour or a spectral gamma ray tool it depends on what do you want to do in this case you will go only for the total gamma ray tool which is the one that measures the total activity or gamma ray activity of the the rock that we are facing these two is called the gamma ray the gamma rays okay so the second tool is most important is the gamma rays then we go for the two that measures porosity which is the neutral so this is the third one that we that we run the neutron tool is the tool that measure neutron process okay we actually talked about this tool before and we we say that this tool actually measures the hydrogen concentration or hydrogen index or the or the number of hydrogen atoms you know take it anywhere you like just to explain to yourself what this tool is actually read then we go for the rocket lithology which is combining the neutron tool and another is called the density the density it will give us the density of the rock that the tool is c when we combine the neutron and the density will come up with very interesting type of analysis that will help us identify our reservoir then the last but not the least is the flu saturation tool which is actually there is a stability so this is the box of the two these are the basic tools that we measure that we use we call this treble combo triple combo stands for neutron density and the resistivity someone will ask out about what about the gamma ray and then the and the caliper we call this our basic tools that they run with every run regardless of what you do okay when you go and you go into the world board it's better to have a caliper with you and to have a gamma-ray tool even if you don't have any other tool.district so we don't really consider this tool as part of the treble combo before these are basics required tool that we have to run in every every time we descend anything into the world okay so combining this tool actually which is a gamma ray neutron density resistivity and caliper what we will measure with this that is all the waterfall diameters we will talk about the border hole diameter and we how we can use this to really find out the our reservoir then we look at the the porosity frosty is a poor space between the grains of the rock that we have for this porosity then we'll go for the lithology and we're combining the density and the neutron tool for lithology then we'll go for the fluids what type of fluids do we have is this water for hydrocarbon but this is a very important thing if we don't have other carbon in the zone there is no need to go and and do anything we don't have to completely so it could be a waste of money in this case then we'll go for the flow situation as i said is it water or is it we need to understand that some actually effects of clays which is a very important thing that every every analyst needs to pay attention to but one thing is that that the most important is is the clay that i see in my raw is this actually affecting my process why because we know that clays prefer to actually get deposited where the water is okay so all clays actually live in the poor space or between the different layers okay so if the clay lives in the pore space then it will clog the pores it will reduce my porosity we call this in this case effective porosity so effective porosity means the actual porosity that is started you subtract from this the part that is occupied by the clay because as i said clays actually like to stay in the water and the and the originally all the pores are filled with water so at the deposition time clay is actually prepared to be inside inside the four space this is very harmful to our trust let me give you an example of this here is a thin section of a core under the microscope we actually look at this and it's just enlarged for example this this this window right here when i unlock this window you can see here is the here are the grains and the one that's blue here are is the pore space so look at the porosity here it's very clearly that the frost here is very very nice and i can see it very clean very clean porosity and this is a good process that doesn't have much of clay in it in the same section if i go and just take another part another section if i put this section under the microscope and enlarge it you can see here is the pore but the porosity is completely filled with with with clay and the clays are really destroying my porosity and my my porosity here we call it the effective porosity is actually zero i don't really have any effective porosity here because all the pores are filled with the clays there is no room for my hydrocarbon with my grit there is no room for my hydrocarbon to live and that's why we call this really destroying destroying my pore space and the effective frost the porosity that i will produce from is actually zero in this case so it is very important to find out how much clay do i have and where does the clay live okay and how much arm does this clay is actually causing to my to my force now when i start looking at evaluation of my reservoir i look at three different stages let's just take this stage by state pay attention to this guy what i have here i have four tools gamma ray neutron resistivity and density plus the caliber that i talked about using these tools i have three stages i have to go through there stage five stage so i will divide the the process into three stages the first one is data quality control which you call it environmental correction you should not do any type of evaluation of any data that you have unless you do environmental correction what does it mean by environmental correction well your tools before they leave the service company and you go to the field these tools are calibrated calibrated to make sure they function properly but when they calibrated they calibrated based on api calibration the american petroleum institute calibration procedure okay this calibration is different than the environment that you put the tool in for example if you have a mod that has a kcl you're just waving your mod by kcl or we will not buy a bentonite uh weighing your mod by whatever these are not part of the api calibration okay api api calibration has a certain procedure and standard and since you ran your tool in a different environment than the api environment then you need to do what we call environmental correction so environmental correlation has nothing to do with your reservoir has nothing to do with that i can see all those many people confuse between corrections and environmental correction environmental corrections is the borehole fluid correction what you use to drill the well with because you can drill your well with oil bisma i a third guy will drill his will with some light drilling float so in this case we all use different environment that's what we call environmental correction so what is environmental creation guys don't confuse this with your reservoir has nothing to do with your reservoir environmental correction is what you did you during drilling the well what what fluid you use when you drill the well what damage you did in your will one of the damage is for hole size you're supposed to drill eight and a half inch hole and unfortunately your reservoir has certain type of properties that you generated at a ten inch wool bowl and it's not actually an eight and a half inch okay so that's exactly what the environmental correction is all about so environmental construction again i'm repeating myself it is the effect of your drilling fluids on that on the underlogging tools has nothing to do with your reservoir am i clear on this the second part is once you did the environmental corrections to you too then you go and calculate the porosity and the lithology in this case because now you have the dog the logs in its proper environment then you can use this corrected logs for calculating the proper porosity and ecology once you calculated the porosity and the lithology then you start calculating fluids hydrocarbon and water so there are three steps environmental corrections mythology and porosity influence okay within these three major steps there are minor steps that you need to do okay let's just start by one by one one by one data quality control which is the environmental correction the first one to do is borehole size correction caliper correction because you intended to drill twelve and a quarter hole but unfortunately your your drilling was not in a very good shape your wheel board is not in a very good shape you deteriorated the world ball you it to drill eight and a half inch hole unfortunately it didn't go very well then your hole is not eight and a half inches it's not a gauge drawer so in this case you need to do environmental corrections which is bore hole size correction you need to remove the effect of the extras that you have on the undertones okay second is mud with correction your mud weight is ten and a half ppg my my whatever it is my so your mother which is different than my module we use the same tool we use the neutron tool for example let's say flammagio neutron tool or haliburton density tool it's the same tool but you put it in a different environment then your tool will read different than mine so in this case i need to remove this effect that's what we do the mud weight correction so mud width collision because your mod width is different than mine third is maxillinitical for example you used in acl you use the sodium chloride okay or your muscle length is much higher than my you use 150 000 ppm um mozzarella and i use 200 000 ppm or i use 30 000 ppm so i need to correct for this because your your environment is different than mine like the first one is the mud additives for example do i have alright do i have kcl i have to do this corrections as well so we're corrected for the volvo size correctness from the modulate correctly for the maxillinity corrected for demand additives okay also we need to call for temperature you actually uh logging a zone at 5000 feet according to the temperature gradient your temperature is say 80 degrees okay and i'm drilling my reservoir is at 12 000 feet so my temperature would say 150 000 i'm sorry 150 degrees so in this case your temperature is different than mine your pressure is different than mine so i have to correct for temperature and pressure so these are the major environmental connections that we need to apply to make sure that we remove all the environmental effects from my login data then when i use this login data after the correction i calculate the proper parameters okay so the overall correction modulates correction masalinity mod additives temperature and pressure we need to correct for all of this we'll show you how we do this in in in a second but these are the the measuring steps then you go for the porosity and the lithology first of all you calculate clay volume here we'll show how calculate play volume we use the gamma ray to do this so i use the gamma ray to calculate the clay body i use the density to calculate the density processing okay so i calculate a volume i calculate density process it means i use the density to calculate porosity okay we'll show you how to do this we discussed this also in one of the previous seminars when we talked about the density then we averaged the neutron and the density because in our interpretation and and pay attention to this neither the neutron prostate is correct neither the density process is great none of them is correct the correct value of process is the average of both okay so the correct value of your reservoir porosity is not the neutron for us and it's not the density calculated porosity it is the average of the neutron density process sometimes probably when you go and for training or something you hear something different that when siddha of the average we call it the cross plot porosity cross plot porosity is exactly what i'm talking about cross plot porosity is the average neutron density okay so let's just look at san typically instead of you talk about the field field language scientifically means the the right porosity of your reservoir is not the neutron process and it's not the density frost it's the average that's why we calculate the density prostate as a previous step then we add it to the neutron and we average both to get the average neutron density across but this is the total one i didn't correct for the clay yet all i did is i calculated the clay volume but i didn't correct for it yet so the next step is to use the clay volume and use the average neutron density prostate and you get the effective porosity effective prostate means you take this total prostate that you calculated from the neutron density and you correct for the effect of the clay volume inside your four space i'll show you how to do that so the next step is the first step is clay volume density porosity neutron density average porosity effective frosty by correcting for clay then you can come up with a lithology prediction of lithology and we will stop on this actually for a while because mythology is a very important thing i will show you some tricks of how to find out the already are in the sandy stone formation limestone information follow my information there are very quick ways of finding this out so once you ended you ended up with the identification of prostate and lithology then you go for the fluids flow saturation you calculate both water saturation and hydrocarbon saturation then you start plotting your fate okay so this actually the process that you see here three major steps with ev with minor steps or itemization of steps within every major measure one okay so let's start with doing this formation evaluation workflow application in a real logging day let's just take an example here real example and see how we're going to apply this process on so the first one is load all your data to a certain software because you cannot do environmental corrections unless you have a certain software all software that we have in the market i'm not going to mention names but if you have a software and suppose in your school you're supposed to have a a software in your in your computer lab that deals with logging data so if you do have this you will find that in every software you use there is always a some way of environmentally correcting the data that you have for every company that runs any tool you would see correction for schlamager aleppo baker weatherford which whatever the the company you're using you will find protection for let's just go for for certain here is the data so i have actually certain certain well here where i have the gamma ray and caliper in the first track here is the bit size i used so i drilled this big big hole first smaller hole than the smallest one it is the actual wheelbarrow shape different than the bit which should be you know okay so here is here is your actual wool board here is the resistivity and here is the neutron density so i have gamma-ray caliper i have resistivity and i have neutron density this is the shape of my willpower okay if you look at the first hole this is a 16 inch hole followed by twelve and a quarter inch hole followed by eight and a half inch so i have a well here that went to 16 inch twelve and a quarter and eight and a half and you need to apply the environmental connections for it okay so once we loaded the data then we need to find which company actually logged this world because every company has its own environmental correction okay so we need to find this out which company ran this law if you go to the data file or you go to the printout that the company will send to you the service company who sent you you know which company actually thrilled i'm sorry which company actually logged this one okay so we you so you know that in this case now if i open the the data file here i will very easily locate the company here's the service company schlumberger so from the login data i can find this out easily service company is slumber the service company login combination so now i find out that or i found out that the company that ran this this this world logged it is a slumber okay then you need to apply caliper correction material all the correction that we that we talked about here let's just start one by one for example here is my software i'm using i'm not going to mention the name of the software as i said if i go here for calculation it goes for a tab here called environmental connection and when i clicked on environmental correction it gave me all the companies here is schlumberger here is baker halliburton and adrenal bakery every every company that you will be able to use is actually in the list here okay so this is important now we knew that it would have to choose okay when i chose it is the company because i knew from the from the data file that that logan company is schlumberg when i started this slumberg correction i have actually here if i look i have then a gamma ray i have density i have cnl which is a compensated neutron i need to correct for these three one by one if i go for everyone for example let's just go for the gamma ray here is my gamma ray in the gamma ray he will ask me first of all what is your gamma ray input club i have to choose my gamma ray input so i have fro from here and at this point i will have to choose from the data i have my gamma ray input what is the name of gamma ray input it will give me a gamma ray c gamma ray corrected so after the correction it will actually give me a new curve it's called gamma ray correct corrected for what for the environmental correction that you have what are this environmental correction it will ask you what is the caliper currently because the caliber will give you the diameter of the wheelball so you choose the caliber curve now it will ask you did you run do you need borehole corrections yes i need more hole correction so we click on the moral correction it will ask you did you run it centralized tool or eccentric tool so you can you tell them it's a centralized or eccentric you choose the one that you run the tool with what is the mod type [Music] for example mine is not variety so i choose no or i choose variety if i would okay is it open door or it scares the hole no it is open hole so i take the open hole it will ask you what is your mud wig that you use here is my mod way what type of tool there tool the tool diameter that will be also given to you by the service company okay all the information required once you hit run it will run this and give you the new curve the new curve is called gamma ray c or gamma ray corrected okay that doesn't mean it will remove the original one no it will keep the old one and also give you a new one that is corrected for for the environmental correction you do the same for the density for example in the density here it would ask you what is your density in the curve curve density name it will give you raw corrective so this is the input this is the output what is the photoelectric curve that you have it is a photoelectric curve here is the corrected one uh what's what is the caliper curve name to which you choose the carbon core name you need for hole correction yes i need for whole correction which you do you so you as i said you fill all this information which you know in your then from your database and you choose this and you get the intensity correct you do the same for the neutron again and the neutrons will ask you what again what is the what is the neutron curve name and it will to name it same curve and see c means correct and i say i do repeat again it will keep the original one and it gives you a new one which is the corrected one then it will ask you do you need overall correction size correction you need more do it mod kick correction you need salinity correction whatever the corrections you have once you filled all this data you run it you run the tab and then it will give you corrected once i finished all the correction it's better actually to draw the original one and the corrected one to see how much correction that will be if you remember our borehole was not really that bad okay the world was not very highly washed out so my expectation that the correction will not do much in this case because when i plotted the bit size and i plotted my actual borehole shape it didn't really differ much it was very small variation it means the drilling was in a good shape okay so the wheel was in a good shape so the expectation is i don't have much correction now if i compare here as i expected here is my gamma the first left my gamma ray and my gamma ray correct it is my rho which is a density and density correct here is my neutron and neutron correctly it is my photoelectron photoelectric corrected one of them the original one is black the corrected one is red and you can see the black and red are very nicely overlaying which means that there is not really much of correction which i expected to happen because my will board shape was not in a very bad shape okay so that's why the corrections were in a good shape right so the first step is you need to make sure you apply the environmental correction on all the data that you get from the service company login login europe okay the second step is visual lithology i need you guys to pay attention to this because this is something that i want you to to gain that experience of how can i by looking at the data i can tell you this reservoir sandstorm or this reservoir is limestone or this reservoir is dolomia i can tell you this this section is lion stone this section is the store and you need to build this skill okay you're not going to be able to build this skill unless you really understand how the tools work okay because every tool will respond to lithology in a different way okay for example we all know wherever you work if you work here in far eastern fork in in north africa and in the us we all have what we call the stratigraphic problem we know the stereographic call that the column actually changes for example i'm i'm showing here one of the stratographic columns in egypt which is very complicated that's why i showed this to you because it has a lot of features here for example i have anhydride i have highlight which is sold i have limestone i have sand i have dolomite so i have so many of them how the log will react to this and how by looking at the log i can tell you the log is seeing and hydride the log is seeing our light which is the soul the log is seeing sandy storm the log is seeing limestone so in this case i need to build this skill so let's just take it step by step let's assume that i have a certain sequence here the top one is clay followed by anhydrite followed by salt followed by clay followed by sand followed by anhydride followed by lime followed by dolomite clay and it's a very complicated stratigraphic problem similar to what i just showed you in in the uh in the gulf of suicide in egypt i can actually predict before even i put the tools inside my wheelbar i can predict how the tool will react if it sees any of these any of these rocks okay so let's go one by one in the first track i will actually divide it from 0 to 150 and this is my gamma ray track what's my expectation when the gamma ray sees a clay zone when the gamma ray sees the clay zone clay has potassium thorium and uranium or potassium thorium probably some of the uranium and it will see a very high gamma reactivity so that's why potassium is radioactive thorium is radioactive so from the okay but followed by what followed by an anhydride does the anhydride actually have any potassium in it in destruction it's an iron sulfate it doesn't have any potassium okay does it have any thorium in it or it doesn't have any thorium so if there is no potassium or thorium in any rock will the rock actually read high gamma ray no so it actually requires me knowing what type of rock i'm dealing with you should follow the salt what is so salt is is sodium chloride nacl does it have potassium no does it have thorium and destruction no so if it doesn't have potassium or thorium what's your expectation of the gamma ray it should not read eye gamma it should read logan so by knowing the rock i can predict what the tour would see then when it goes to clay it will read high gamma ray again how about the sensor it depends if the sandstone is clean it will read very low clean means it doesn't have any clay component but if the sense of descent is shearly said it has high clay component it will read high gamma ray but is not very high gamma ray like the clay it will read higher gamma ray okay so i would see gamma ray reading little bit high but is not as high as the clay because clay is a hundred percent hundred percent of of radioactivity coming from that so my expectation in this case go this way clay will read high and the anhydride and the salt elite read low when it goes back to clay it should read high in the sandstone it depends now high or low depends on how much you have when it goes into anhydride it has to lead very low limestone can be high or low depends does it have clay or not dolomite high or low doesn't matter clay it goes back to high and hydride has to go back to low so these are the expectations i have for dragon ball now what are the expectations for the neutron tendency let's just draw the neutron and the things first let's go for the neutron neutron will go from 45 to negative 15 as we agreed before and there is a zero here is the zero prostitute okay so this is negative 15 here is the zero cross why am i putting the zero porosity because we need to go and find out what is the reading of the neutron will be if the neutron actually passes in front of a clay zone will it read frosty or not let's just go back and find out the neutron tool measures the hydrogen component forget about the porosity the neutron is measuring hydrogen component does the clay have hydrogen yes because clay has h2o and clays have oh okay so clays have h2o and we have oh both have hydrogen that's why in front of the clay the neutron tool will read very high why because the neutron 2 responds to hydrogen and clays they have a lot of hydrogen okay how about the anhydride is there any hydrogen in the hydrides for composition no iron sulfate doesn't have any hydrogen in it okay how about the soil well in acl there is no hydrogen so in front of the anhydride and in front of the soil the neutron tool should read very close to zero okay so it should not read any porosity whatsoever to my expectation that if it hits the soul or it hits the anhydride it should read zero because there is no hydrogen in there remember neutron 2 responds to hydrogen as an engineer but i need to you need to think like an engineer as an engineer you need to find out does this mineral have hydrogen no or yes if it has hydrogen neutron tool will read processing if it doesn't neutron tool will read zero very simple okay now if it goes back to clay it will read high how about the sandstone it depends on the prostate if it has five percent porosity it will need less protein is first if it has 25 percent procedure eyebrows so in sandstone it depends on the frost however it goes back to anhydrous that doesn't have any height and this has to eat zero how about the limestone again it depends on porosity how about it depends on us how about that it's very high how about the anhydride it is very low absolute zero so my expectation is here is the neutron 2 it will read high porosity here is the 45 to read high porosity in front of place when it goes to anhydride and salt it will read zero okay no hydrogen in there it will read now it goes to the clay again here it will read high cross goes to sandstone it can really die it depends on how much porosity they have but once it sees the anhydride it goes back to zero why android doesn't have any thrust limestone it will read high profile dolomites very high price in front of clay drops down to zero in front of one i hope that you guys understand now how how these things are related to each other okay how about the density density will do the same okay go for density 2.95 to 1.95 and it will go this way what is the density of clays it needs to place 2.6 2.7 so it will read something similar to this density how about the density of anhydride very heavy and hydride has a very height is 2.98 so that's why it goes all the way to the right two point nine five here and exceeded about the stool so it is about 2.1 so it goes back to 2.1 okay close to 2.1 and so on so knowing knowing the understanding of what each tool will respond to i can predict what the from this point on what i want you to to get out of this comparison or this analysis i'm doing here is one thing first of all if i see the neutron look at this and keep this in your mind if i see the neutron going going to the left and i see the density going to the right with a separation that's exactly a clay zone so the clay zone has two properties the first one the gamma ray is hard second one is neutron and density are separated where neutron is in the left and density is going to the right once i see the neutron to the density to the right and the gamma ray is high you can stamp on this zone it's a clay zone okay now go to the sand sand is opposite of the clay look at this clay was neutron to the left and density to the right when it's actually opposite where the density is to the left and the neutron to the right gamma ray is not very high like the clay that's a sandstone response so again what is the sandstone response neutron density to the left neutron to the right again density left neutron right that's the sandy stone if it's actually neutral lift and density right that's a clay okay now if i go here we are overlaying no separation that's a limestone if the neutron and the density are not separated it's a limestone so when the neutral and the density are overlaying you can stand there that's a limestone when they separate similar to the clay look at the clay clay neutral lift and density rod here is neutral lift and density right then if the clay is the same as no clay has another thing gamma ray is high but dolomite no gamma rays should not be that high because it's a reservoir okay so when i see gamma ray is low and the separation is similar to the clay separation that's another one okay guys and probably this is the first time to hear this but i wouldn't want you to at least if you get out of this webinar with this understand look at this when gamma ray is high okay and neutron to the left density to the right that's a clay signature when the gamma ray is low and the opposite happen density to the left neutral to the right that's a sandstone signature when gamma ray is low and the and the density are overlaying that's a limestone signature okay when the density is on the uh neutron is left density is similar to the clay but the gamma ray is low i hope this is actually clear to everyone let me apply this to a to this example i have neutron and i have density here okay everybody everyone can see that i have neutron and have density look at this here is my neutron to the left density to the right how can i identify the glaze i said high gamma interest then neutron lift and density right this is the signature let's look at the here gamma rays high here is high gallery is the neutron lift yes the neutron is left is the density right yes the density is right so this stone has to be a clay zone how about this one gamma rays are look at this and if i go there uh you know neutron is left density is neutron always is blue neutron is left density is right then this is a clay zone if i go to this peak i gamma ray i go there neutron is left density is russia this is a clay zone again high gamma ray high gamma ray very high gamma ray then i can actually say all these zones are clay zones here is a clay zone here is a clay zone here is a clay zone here is the collision and so on so the clay zones they have i gamma ray we have neutron lift and density okay resistivity has to be low as well why because all these plays are very conductive so sympathy is glorious activities glory sensitivity is gone it's just a confirmation i always confirm this with my eyes that these are plays clayson okay now the non clay zone we said gamma ray has to be low lower than lower than the glaze now if the neutron is right and the density is left opposite to the clay we call this what we call this sandisk let's just look at this it is a lower gamma ray compared to the decline here is the clay zone it is a lower gamma rays here is the opposite look at this neutron here who's left density is actually changed the density is left and the neutron is right so i actually know for sure that this zone is sandisk okay similarly this zone is sandy stone this is only sandy stone and so on so i can actually they say this the neutron here is is essential if the overlay it's limestone if they actually have the same separation like the the the clay it's dolomite so applying these rules this reservoir is absolutely ascendant so by visualization i knew this reservoir is a sandstone reservoir okay everybody understand that it's very very important to train your eyes i'm not sure if you guys uh study this at your at your universities or not but we teach this at the american university here we actually get the students to pick all these zones by their visualization before even using the software so you get trained on how to identify the different mythology from the actual logging date okay how can i calculate the clay volume and the porosity to calculate the clay volume first of all we need to identify what is the minimum clay reading in my reservoir you go there and search for the minimum play reading here is my minimum play reading i decide what is your minimum clarity also go and find the maximum clarity so you put your gamma ray between minimum and maximum okay once you define the minimum and you find the maximum then you calculate the clay volume from the very well-known linear clay correlation gamma ray minus gamma-ray clean divided by gamma-ray shale minus gamma-ray clean or we can call it gamma-ray minus gamma membrane minimum divided by gamma-ray maximum minus gamma ray you apply this on the entire world then you calculate the clay form so how can i calculate the clay volume first of all you look at the logs you decide what is the minimum reading of gamma ray and what is the maximum reading of gamma ray the minimum readable memory you call it gamma ray key maximum reading of gamma ray you call it gamma ray shape okay then you start using these two values to calculate the clay point okay once you calculate the clay volume you plot it from zero to one one is a hundred percent zero is a zero percent now i calculated this and here is my weak layer i calculated my declare as using the gamma the equation gamma ray minus gamma ray minimum divided by gamma and maximum minus governing okay now we need to shade the clay so now shaded the clay here so now i i know exactly my clay volume where and how much do i have at every point once you calculate the declare volume then we need to calculate process we said to calculate porosity first you calculate density process then you calculate the average neutron density process remember this is very very important how can i calculate the density porosity easy your row bulk the density that you calculated minus 2.71 divided by 1 minus 2.71 don't change the 2.71 because somebody will say you just told us that it's sandstone and sandstone is 2.65 actually this is true but remember your neutron porosity is on limestone you cannot put the neutron pressure on limestone and you calculate the density process on the sandy stone that's and that's it's not this that's what you call the bias that's not that should not do that but since your neutron is in limestone then your density porosity has to be also on limestone for consistency okay the average will take a we'll take will take the the all this ambiguity out that's why we average both neither the neutron is correct neither the density is correct the average neutron density is the correct okay to calculate the average by com by adding the free neutron plus feed density divided by okay so the feed density guys you have to use the 2.71 despite that we just identified that the rock is sandy stone it doesn't matter you still use the you still use the uh limestone density because your neutron is on limestone escape somebody will say well in my country we don't use limestone scale we use sandstone so in this case you use 2.65 if your neutron is online stony scale use 2.71 if your neutron is on sandstone scale sometimes in the us for example you use sandstone scale 1.65 2.65 so in this case you have to calculate density prosthesis then you take an average neutron density process okay now once you calculated the average nutrient density process you need to correct it for the clay how can i correct it for the clay we call it effective it's actually the neutron density average minus we clay times p hundred percent clay what's a few hundred percent clay it is the reading of the clay of the neutron density in front of the hundred percent clay look at your log you go back to your logs it again and you look at the high gamma ray zone which is 100 clay and read the neutron and density prostate there so this is what you call the hundred percent clay point so the neutron density minus clay volume that you just calculated multiplied by the velocity of a hundred percent clay you have a zone in your new log it's a hundred percent clay zone that you identify okay which is the zone that has the maximum gamma ray reading look at the neutron density there and read the value this is the value of the hundred percent clay point once you do this then you calculate so this is actually read the neutron density in front of the hundred percent clay volume this is the value there so you calculated the neutron density process already you calculated the weakly and you find this from the load you go to the maximum value of gamma ray and read the neutron density in front of it so this is the reading of the neutron density in front of the hundred percent clay and you do the calculation to calculate the expected for us the new plot so here is my effective process okay my expectation is in front of a very high gamma ray i don't have really effective for us my clay is hurting my prostate it actually going back to zero okay if i look at look at this here are very high gamma ray streak what happened to my porosity destroyed zero here is the high gamma ray streak how what happened my prostate zero it is a hundred percent clay what happened to my prostate zero okay so once i have this it's clear now in front of a hundred percent clay by reading it has to be zero very very low effective for us okay then here is my clay volume here is my process what is the rest this is my lithology my rock and we identified the rock as ascen okay we said that this is only sandstone we just looked at this it's a sand stone now we can actually look at it as a sand stone and your lithology is a sandy stone so i know now here is my clay volume my little sandstone and here is my here is my crust so i calculated my effective prostate i calculated my clay volume and i knew my reservoir is sandy stone so i actually came up with that very interesting picture of a very quick analysis i did not calculate how much water or how much hydrocarbon yet so that's the next step what's left is how much water and how much hydrocarbon do i have in my poor space sw and sh is a hydrocarbon for simplicity use rc in this case because this is remember this is a quick look when you go back to the office if archie is too simplistic for this reservoir use a different model but at least for the quick look you can calculate rc very very straightforward are she here i have to know what is rw i have to know what's a m and n for sure in your reservoir these parameters are known once you know these parameters and you calculated your porosity you measured your resistivity then you can easily calculate calculate the step once you calculated this w if you multiply this w times the porosity it gives you the the part of the force that actually contains water it is established assume it's w it's 40 and you have 10 pu this means that four pu are filled with water and six pu are filled with with hydrocarb okay that's what 40 percent mean 40 water saturation means out of the 10 pu that you have four pu are filled with water and six few are filled with hydrocarbons so you multiply sw by the porosity gives you the volume of the four space that's actually filled filled with water and you put this and you and you draw this and you and you and you color it as blue because blue in our coloring moves means water so this is blue about the rest if this is this part is blue is blue which is water and then the rest will be will be the hydrocarbon we should put it as as green so my hydrocarbon will be as so as you can see here i calculated my hydrocarbon volume and i calculated my water volume with a very very quick way of calculation it's not really very difficult it's very straightforward okay calculating your clay volume calculating your effective porosity and then you calculate your hydrocarbon saturation very quickly you can do that on the radio if you are if you actually visit the legs you can go and do this on the leg and you can make a decision which zone i need to perforate which is what i need to complete or this world doesn't have any potential so you can actually have this quick look in your mind by doing very very simple calculations until you go back to the others and then you start doing more complex analysis that fits your reservoir modeling as you do in the in the company that the journal would be would be working so in summary to have a quick look well evaluation then what you do to perform the following you do environmentally corrected logs then you do a quick look visual lithology determination then you do clay volume calculations then you go for density porosity calculation then you go for neutron density average frosty calculation then you correct that to go for effective porosity correct clay corrected neutron this will affect the porosity then you calculate the water saturation using then you end up with knowing which zone it has the potential of being a producing zone or not thank you very much actually hope that you guys uh learned something from this webinar and i'll be very happy to entertain some of the questions dr mustafa thank you very much for the amazing uh webinar as usual i have a few questions for you the first question um can we rely on the measurement of the density log in the casing section in the case the section he means it seems like he's asking about cased whole logging okay no there is no no measurement of density in casing okay what we actually covered here is open hole analysis case the whole we don't we have neutrons through casing but we do not have density suitcase quite frankly when i was with halliburton before there was big project on trying to find a tool that can measure density behind casing i don't think it's successful and i don't think there's any company that can do that it's very complicated as is in neutrons it's very complicated as is even in the gamma ray corrections so having a density measurement that has very very high sensitivity to any type of uh variation in the wool board if you put the casing and you put the cement also add it will add much more difficulty for the density up to my knowledge there is no density through casing anyway a second question about gulf of sways in egypt to what extent the geological column of gulf of swayze is valid also is it different from another area in egypt absolutely god for sources are one of the most complicated you will ever face if you work in the gulf of south it's really very complicated it's different than the eastern desert different than the western desert completely different if you if you can find your way in in the gulf of waste believe me or not you would be an excellent petrol physicist because the challenges there are very very challenges in drilling challenges in evaluation lots of falls lots of uh anhydride lots of lots of salt sections which is a highlight very highly intermediate very thin vertically very thin layers uh you know things are you know known on when things happen across crossing the red sea i think it's caused a lot of issues uh interesting structure so the uh that this is very complicated one fatima is asking about if we have a sandstone formation how we know if it has water or hydrocarbon you have a sense so from how we know it has water we just covered that at the very end once you calculated your effective porosity then all you need to do is to use rc as a simplistic way first use rc uh calculate rc sw multiply and see what this w is the sw above six seventy percent eighty percent that's bad luck if this w twenty thirty forty percent then then you still have a result another question uh r p e log and p e f are the same what's the e yellow p e log oh p e and the second one is actually it's the same one some companies call it p e yes some kind of some companies call it p e photoelectric and some company called pef photoelectric factor it's the same thing it is it is the same thing it's just a different different naming but it is essentially the same thing which is z over 10 to the power of 3.6 which is the this is what the p e is so the f is it stands for factor some companies they call it photoelectric some some common is called photoelectric effect but they are both they both are the same another question do we use rc equation for carbonate too you remember when i started talking about talking about this webinar i said this is quick look something that you will actually need an answer now okay if i need an answer now i don't have a problem doing some approximations okay even if you don't know what a m and n is go for one two two okay so you can have a very quick one now if this quick one gave me sw as a 10 percent for example well probably the exact one will make it 20. so it's not going to make a big difference so it's not going to change from being a hydrocarbon zone to our waters okay so that approximation is not going to do this but if the sw came as 90 well to never be 10 percent if you apply the exact equation it will be still 80 percent 75 percent still i would still a with zone okay so my point is if you go for on she as a quick look analysis quick look and i stressed on this at the beginning this is a quick look a decision i need to do now i don't have enough time to leave the rig there that's costing me a hundred thousand dollars per day for someone to go and wake up and wash his face and sit in front of a computer and take his time to do the analysis and i'm paying money on direct no i need somebody to make a decision now to make sure do i let that be the right release or i need to stay and complete the work then at this time i can use ash once you're done with this you made your decision when you go back to your office then do whatever sophisticated for you i agree with you archie is not the most suitable for carbonate but as a quick look it is okay for carbonate as a good one another question is it possible to have mechanical errors in the logging tool and how we can find out that mechanical one mechanical errors you mean by mechanical errors mean mechanical tool errors yeah it seems like something wrong with equipment itself for sure but the but the field engineer will find this out easy and any trained engineer will will be able to find if there is anything in the connectivity between tools it's not clear what the question is but anyways if you if this is what he means a very well-trained engineer would be able to find this the last question uh is it possible to have the slides uh unfortunately unfortunately you know but you will have a webinar you can watch it as much as you want okay dr mustafa thank you very much and please enjoy your rest of the day if you have any rest of today i believe you have evening now so enjoy your evening yeah thank you guys very much appreciate it and look forward to seeing you guys some somewhere in this world okay have a good evening you too bye bye

okay uh let me start uh just saying good morning good afternoon and good evening wherever you are my name is mustafa orby i&#39;m the graduate program director and also a professor of the petroleum engineering at the american university in cairo i&#39;ve been with the industry for almost 25 years finally i need to pay back some some some part of my experiences to the academia that&#39;s why i&#39;m joining the the american university in china okay today actually i will start talking about the formation evaluation not from just the tools point of view we covered this in the previous lectures so if you need to go and back and refresh your memory on tools and two responses and what are the design of each tool what each tool actually measures in this case you need to i will refer you back to some of the uh petrol and the arab oil and gas academy database that you can actually go and watch this video today i will assume that you guys know these login tools so how can we use we combine all these tools to come up with a very quick look well notice when i say quick look because there are actually two different type of analysis something that we do very quickly especially if the if the rig is waiting on our decision uh will we continue completing this zone uh this one is our potential zone or not uh how can we define this out with a very quick evaluation then we go for complex uh well analysis that goes back after you go back to the office and you start doing in-depth analysis of the logging data and also you share this with the geogeologists the geophysicist to come up with a broader understanding of the geological and the structure of your of your reservoir that goes for the reservoir characterization and the structure but for the very quick evaluation of do we really need to complete this zone or not uh is this well and i would put in a good place or not what is a pays on how big is the pay zone uh how much porosity do i have these type of things which is a very quick thing that that will help us make a good decision okay so with that said let me start with saying basic wire line logging data that we all use when i say why online because we covered here in this webinars and the previous webinars only the wire line logging data there are also loading while drilling equipment and tools that we can use they deliver similar measurements with some differences based on the environment that each of these tools actually are run in so in this case there are some differences between them but for the time being we&#39;re talking about the wire line logging this means the drilling is over no drilling it&#39;s only the wire line using the one line cable we acquire certain type of data okay the first one is the the borehole caliper oral caliper is the one that we actually use to find out what is the borehole size what is the diameter of the borehole at every depth why do we need to do to know that we&#39;ll talk about this in a minute so we have a tool that measures the borehole they enter at every depth that every measurement we do one of the measurements is is abort or damp we do this with a character then we run another two which is called the gamma ray to either total gamma ray tour or a spectral gamma ray tool it depends on what do you want to do in this case you will go only for the total gamma ray tool which is the one that measures the total activity or gamma ray activity of the the rock that we are facing these two is called the gamma ray the gamma rays okay so the second tool is most important is the gamma rays then we go for the two that measures porosity which is the neutral so this is the third one that we that we run the neutron tool is the tool that measure neutron process okay we actually talked about this tool before and we we say that this tool actually measures the hydrogen concentration or hydrogen index or the or the number of hydrogen atoms you know take it anywhere you like just to explain to yourself what this tool is actually read then we go for the rocket lithology which is combining the neutron tool and another is called the density the density it will give us the density of the rock that the tool is c when we combine the neutron and the density will come up with very interesting type of analysis that will help us identify our reservoir then the last but not the least is the flu saturation tool which is actually there is a stability so this is the box of the two these are the basic tools that we measure that we use we call this treble combo triple combo stands for neutron density and the resistivity someone will ask out about what about the gamma ray and then the and the caliper we call this our basic tools that they run with every run regardless of what you do okay when you go and you go into the world board it&#39;s better to have a caliper with you and to have a gamma-ray tool even if you don&#39;t have any other tool.district so we don&#39;t really consider this tool as part of the treble combo before these are basics required tool that we have to run in every every time we descend anything into the world okay so combining this tool actually which is a gamma ray neutron density resistivity and caliper what we will measure with this that is all the waterfall diameters we will talk about the border hole diameter and we how we can use this to really find out the our reservoir then we look at the the porosity frosty is a poor space between the grains of the rock that we have for this porosity then we&#39;ll go for the lithology and we&#39;re combining the density and the neutron tool for lithology then we&#39;ll go for the fluids what type of fluids do we have is this water for hydrocarbon but this is a very important thing if we don&#39;t have other carbon in the zone there is no need to go and and do anything we don&#39;t have to completely so it could be a waste of money in this case then we&#39;ll go for the flow situation as i said is it water or is it we need to understand that some actually effects of clays which is a very important thing that every every analyst needs to pay attention to but one thing is that that the most important is is the clay that i see in my raw is this actually affecting my process why because we know that clays prefer to actually get deposited where the water is okay so all clays actually live in the poor space or between the different layers okay so if the clay lives in the pore space then it will clog the pores it will reduce my porosity we call this in this case effective porosity so effective porosity means the actual porosity that is started you subtract from this the part that is occupied by the clay because as i said clays actually like to stay in the water and the and the originally all the pores are filled with water so at the deposition time clay is actually prepared to be inside inside the four space this is very harmful to our trust let me give you an example of this here is a thin section of a core under the microscope we actually look at this and it&#39;s just enlarged for example this this this window right here when i unlock this window you can see here is the here are the grains and the one that&#39;s blue here are is the pore space so look at the porosity here it&#39;s very clearly that the frost here is very very nice and i can see it very clean very clean porosity and this is a good process that doesn&#39;t have much of clay in it in the same section if i go and just take another part another section if i put this section under the microscope and enlarge it you can see here is the pore but the porosity is completely filled with with with clay and the clays are really destroying my porosity and my my porosity here we call it the effective porosity is actually zero i don&#39;t really have any effective porosity here because all the pores are filled with the clays there is no room for my hydrocarbon with my grit there is no room for my hydrocarbon to live and that&#39;s why we call this really destroying destroying my pore space and the effective frost the porosity that i will produce from is actually zero in this case so it is very important to find out how much clay do i have and where does the clay live okay and how much arm does this clay is actually causing to my to my force now when i start looking at evaluation of my reservoir i look at three different stages let&#39;s just take this stage by state pay attention to this guy what i have here i have four tools gamma ray neutron resistivity and density plus the caliber that i talked about using these tools i have three stages i have to go through there stage five stage so i will divide the the process into three stages the first one is data quality control which you call it environmental correction you should not do any type of evaluation of any data that you have unless you do environmental correction what does it mean by environmental correction well your tools before they leave the service company and you go to the field these tools are calibrated calibrated to make sure they function properly but when they calibrated they calibrated based on api calibration the american petroleum institute calibration procedure okay this calibration is different than the environment that you put the tool in for example if you have a mod that has a kcl you&#39;re just waving your mod by kcl or we will not buy a bentonite uh weighing your mod by whatever these are not part of the api calibration okay api api calibration has a certain procedure and standard and since you ran your tool in a different environment than the api environment then you need to do what we call environmental correction so environmental correlation has nothing to do with your reservoir has nothing to do with that i can see all those many people confuse between corrections and environmental correction environmental corrections is the borehole fluid correction what you use to drill the well with because you can drill your well with oil bisma i a third guy will drill his will with some light drilling float so in this case we all use different environment that&#39;s what we call environmental correction so what is environmental creation guys don&#39;t confuse this with your reservoir has nothing to do with your reservoir environmental correction is what you did you during drilling the well what what fluid you use when you drill the well what damage you did in your will one of the damage is for hole size you&#39;re supposed to drill eight and a half inch hole and unfortunately your reservoir has certain type of properties that you generated at a ten inch wool bowl and it&#39;s not actually an eight and a half inch okay so that&#39;s exactly what the environmental correction is all about so environmental construction again i&#39;m repeating myself it is the effect of your drilling fluids on that on the underlogging tools has nothing to do with your reservoir am i clear on this the second part is once you did the environmental corrections to you too then you go and calculate the porosity and the lithology in this case because now you have the dog the logs in its proper environment then you can use this corrected logs for calculating the proper porosity and ecology once you calculated the porosity and the lithology then you start calculating fluids hydrocarbon and water so there are three steps environmental corrections mythology and porosity influence okay within these three major steps there are minor steps that you need to do okay let&#39;s just start by one by one one by one data quality control which is the environmental correction the first one to do is borehole size correction caliper correction because you intended to drill twelve and a quarter hole but unfortunately your your drilling was not in a very good shape your wheel board is not in a very good shape you deteriorated the world ball you it to drill eight and a half inch hole unfortunately it didn&#39;t go very well then your hole is not eight and a half inches it&#39;s not a gauge drawer so in this case you need to do environmental corrections which is bore hole size correction you need to remove the effect of the extras that you have on the undertones okay second is mud with correction your mud weight is ten and a half ppg my my whatever it is my so your mother which is different than my module we use the same tool we use the neutron tool for example let&#39;s say flammagio neutron tool or haliburton density tool it&#39;s the same tool but you put it in a different environment then your tool will read different than mine so in this case i need to remove this effect that&#39;s what we do the mud weight correction so mud width collision because your mod width is different than mine third is maxillinitical for example you used in acl you use the sodium chloride okay or your muscle length is much higher than my you use 150 000 ppm um mozzarella and i use 200 000 ppm or i use 30 000 ppm so i need to correct for this because your your environment is different than mine like the first one is the mud additives for example do i have alright do i have kcl i have to do this corrections as well so we&#39;re corrected for the volvo size correctness from the modulate correctly for the maxillinity corrected for demand additives okay also we need to call for temperature you actually uh logging a zone at 5000 feet according to the temperature gradient your temperature is say 80 degrees okay and i&#39;m drilling my reservoir is at 12 000 feet so my temperature would say 150 000 i&#39;m sorry 150 degrees so in this case your temperature is different than mine your pressure is different than mine so i have to correct for temperature and pressure so these are the major environmental connections that we need to apply to make sure that we remove all the environmental effects from my login data then when i use this login data after the correction i calculate the proper parameters okay so the overall correction modulates correction masalinity mod additives temperature and pressure we need to correct for all of this we&#39;ll show you how we do this in in in a second but these are the the measuring steps then you go for the porosity and the lithology first of all you calculate clay volume here we&#39;ll show how calculate play volume we use the gamma ray to do this so i use the gamma ray to calculate the clay body i use the density to calculate the density processing okay so i calculate a volume i calculate density process it means i use the density to calculate porosity okay we&#39;ll show you how to do this we discussed this also in one of the previous seminars when we talked about the density then we averaged the neutron and the density because in our interpretation and and pay attention to this neither the neutron prostate is correct neither the density process is great none of them is correct the correct value of process is the average of both okay so the correct value of your reservoir porosity is not the neutron for us and it&#39;s not the density calculated porosity it is the average of the neutron density process sometimes probably when you go and for training or something you hear something different that when siddha of the average we call it the cross plot porosity cross plot porosity is exactly what i&#39;m talking about cross plot porosity is the average neutron density okay so let&#39;s just look at san typically instead of you talk about the field field language scientifically means the the right porosity of your reservoir is not the neutron process and it&#39;s not the density frost it&#39;s the average that&#39;s why we calculate the density prostate as a previous step then we add it to the neutron and we average both to get the average neutron density across but this is the total one i didn&#39;t correct for the clay yet all i did is i calculated the clay volume but i didn&#39;t correct for it yet so the next step is to use the clay volume and use the average neutron density prostate and you get the effective porosity effective prostate means you take this total prostate that you calculated from the neutron density and you correct for the effect of the clay volume inside your four space i&#39;ll show you how to do that so the next step is the first step is clay volume density porosity neutron density average porosity effective frosty by correcting for clay then you can come up with a lithology prediction of lithology and we will stop on this actually for a while because mythology is a very important thing i will show you some tricks of how to find out the already are in the sandy stone formation limestone information follow my information there are very quick ways of finding this out so once you ended you ended up with the identification of prostate and lithology then you go for the fluids flow saturation you calculate both water saturation and hydrocarbon saturation then you start plotting your fate okay so this actually the process that you see here three major steps with ev with minor steps or itemization of steps within every major measure one okay so let&#39;s start with doing this formation evaluation workflow application in a real logging day let&#39;s just take an example here real example and see how we&#39;re going to apply this process on so the first one is load all your data to a certain software because you cannot do environmental corrections unless you have a certain software all software that we have in the market i&#39;m not going to mention names but if you have a software and suppose in your school you&#39;re supposed to have a a software in your in your computer lab that deals with logging data so if you do have this you will find that in every software you use there is always a some way of environmentally correcting the data that you have for every company that runs any tool you would see correction for schlamager aleppo baker weatherford which whatever the the company you&#39;re using you will find protection for let&#39;s just go for for certain here is the data so i have actually certain certain well here where i have the gamma ray and caliper in the first track here is the bit size i used so i drilled this big big hole first smaller hole than the smallest one it is the actual wheelbarrow shape different than the bit which should be you know okay so here is here is your actual wool board here is the resistivity and here is the neutron density so i have gamma-ray caliper i have resistivity and i have neutron density this is the shape of my willpower okay if you look at the first hole this is a 16 inch hole followed by twelve and a quarter inch hole followed by eight and a half inch so i have a well here that went to 16 inch twelve and a quarter and eight and a half and you need to apply the environmental connections for it okay so once we loaded the data then we need to find which company actually logged this world because every company has its own environmental correction okay so we need to find this out which company ran this law if you go to the data file or you go to the printout that the company will send to you the service company who sent you you know which company actually thrilled i&#39;m sorry which company actually logged this one okay so we you so you know that in this case now if i open the the data file here i will very easily locate the company here&#39;s the service company schlumberger so from the login data i can find this out easily service company is slumber the service company login combination so now i find out that or i found out that the company that ran this this this world logged it is a slumber okay then you need to apply caliper correction material all the correction that we that we talked about here let&#39;s just start one by one for example here is my software i&#39;m using i&#39;m not going to mention the name of the software as i said if i go here for calculation it goes for a tab here called environmental connection and when i clicked on environmental correction it gave me all the companies here is schlumberger here is baker halliburton and adrenal bakery every every company that you will be able to use is actually in the list here okay so this is important now we knew that it would have to choose okay when i chose it is the company because i knew from the from the data file that that logan company is schlumberg when i started this slumberg correction i have actually here if i look i have then a gamma ray i have density i have cnl which is a compensated neutron i need to correct for these three one by one if i go for everyone for example let&#39;s just go for the gamma ray here is my gamma ray in the gamma ray he will ask me first of all what is your gamma ray input club i have to choose my gamma ray input so i have fro from here and at this point i will have to choose from the data i have my gamma ray input what is the name of gamma ray input it will give me a gamma ray c gamma ray corrected so after the correction it will actually give me a new curve it&#39;s called gamma ray correct corrected for what for the environmental correction that you have what are this environmental correction it will ask you what is the caliper currently because the caliber will give you the diameter of the wheelball so you choose the caliber curve now it will ask you did you run do you need borehole corrections yes i need more hole correction so we click on the moral correction it will ask you did you run it centralized tool or eccentric tool so you can you tell them it&#39;s a centralized or eccentric you choose the one that you run the tool with what is the mod type [Music] for example mine is not variety so i choose no or i choose variety if i would okay is it open door or it scares the hole no it is open hole so i take the open hole it will ask you what is your mud wig that you use here is my mod way what type of tool there tool the tool diameter that will be also given to you by the service company okay all the information required once you hit run it will run this and give you the new curve the new curve is called gamma ray c or gamma ray corrected okay that doesn&#39;t mean it will remove the original one no it will keep the old one and also give you a new one that is corrected for for the environmental correction you do the same for the density for example in the density here it would ask you what is your density in the curve curve density name it will give you raw corrective so this is the input this is the output what is the photoelectric curve that you have it is a photoelectric curve here is the corrected one uh what&#39;s what is the caliper curve name to which you choose the carbon core name you need for hole correction yes i need for whole correction which you do you so you as i said you fill all this information which you know in your then from your database and you choose this and you get the intensity correct you do the same for the neutron again and the neutrons will ask you what again what is the what is the neutron curve name and it will to name it same curve and see c means correct and i say i do repeat again it will keep the original one and it gives you a new one which is the corrected one then it will ask you do you need overall correction size correction you need more do it mod kick correction you need salinity correction whatever the corrections you have once you filled all this data you run it you run the tab and then it will give you corrected once i finished all the correction it&#39;s better actually to draw the original one and the corrected one to see how much correction that will be if you remember our borehole was not really that bad okay the world was not very highly washed out so my expectation that the correction will not do much in this case because when i plotted the bit size and i plotted my actual borehole shape it didn&#39;t really differ much it was very small variation it means the drilling was in a good shape okay so the wheel was in a good shape so the expectation is i don&#39;t have much correction now if i compare here as i expected here is my gamma the first left my gamma ray and my gamma ray correct it is my rho which is a density and density correct here is my neutron and neutron correctly it is my photoelectron photoelectric corrected one of them the original one is black the corrected one is red and you can see the black and red are very nicely overlaying which means that there is not really much of correction which i expected to happen because my will board shape was not in a very bad shape okay so that&#39;s why the corrections were in a good shape right so the first step is you need to make sure you apply the environmental correction on all the data that you get from the service company login login europe okay the second step is visual lithology i need you guys to pay attention to this because this is something that i want you to to gain that experience of how can i by looking at the data i can tell you this reservoir sandstorm or this reservoir is limestone or this reservoir is dolomia i can tell you this this section is lion stone this section is the store and you need to build this skill okay you&#39;re not going to be able to build this skill unless you really understand how the tools work okay because every tool will respond to lithology in a different way okay for example we all know wherever you work if you work here in far eastern fork in in north africa and in the us we all have what we call the stratigraphic problem we know the stereographic call that the column actually changes for example i&#39;m i&#39;m showing here one of the stratographic columns in egypt which is very complicated that&#39;s why i showed this to you because it has a lot of features here for example i have anhydride i have highlight which is sold i have limestone i have sand i have dolomite so i have so many of them how the log will react to this and how by looking at the log i can tell you the log is seeing and hydride the log is seeing our light which is the soul the log is seeing sandy storm the log is seeing limestone so in this case i need to build this skill so let&#39;s just take it step by step let&#39;s assume that i have a certain sequence here the top one is clay followed by anhydrite followed by salt followed by clay followed by sand followed by anhydride followed by lime followed by dolomite clay and it&#39;s a very complicated stratigraphic problem similar to what i just showed you in in the uh in the gulf of suicide in egypt i can actually predict before even i put the tools inside my wheelbar i can predict how the tool will react if it sees any of these any of these rocks okay so let&#39;s go one by one in the first track i will actually divide it from 0 to 150 and this is my gamma ray track what&#39;s my expectation when the gamma ray sees a clay zone when the gamma ray sees the clay zone clay has potassium thorium and uranium or potassium thorium probably some of the uranium and it will see a very high gamma reactivity so that&#39;s why potassium is radioactive thorium is radioactive so from the okay but followed by what followed by an anhydride does the anhydride actually have any potassium in it in destruction it&#39;s an iron sulfate it doesn&#39;t have any potassium okay does it have any thorium in it or it doesn&#39;t have any thorium so if there is no potassium or thorium in any rock will the rock actually read high gamma ray no so it actually requires me knowing what type of rock i&#39;m dealing with you should follow the salt what is so salt is is sodium chloride nacl does it have potassium no does it have thorium and destruction no so if it doesn&#39;t have potassium or thorium what&#39;s your expectation of the gamma ray it should not read eye gamma it should read logan so by knowing the rock i can predict what the tour would see then when it goes to clay it will read high gamma ray again how about the sensor it depends if the sandstone is clean it will read very low clean means it doesn&#39;t have any clay component but if the sense of descent is shearly said it has high clay component it will read high gamma ray but is not very high gamma ray like the clay it will read higher gamma ray okay so i would see gamma ray reading little bit high but is not as high as the clay because clay is a hundred percent hundred percent of of radioactivity coming from that so my expectation in this case go this way clay will read high and the anhydride and the salt elite read low when it goes back to clay it should read high in the sandstone it depends now high or low depends on how much you have when it goes into anhydride it has to lead very low limestone can be high or low depends does it have clay or not dolomite high or low doesn&#39;t matter clay it goes back to high and hydride has to go back to low so these are the expectations i have for dragon ball now what are the expectations for the neutron tendency let&#39;s just draw the neutron and the things first let&#39;s go for the neutron neutron will go from 45 to negative 15 as we agreed before and there is a zero here is the zero prostitute okay so this is negative 15 here is the zero cross why am i putting the zero porosity because we need to go and find out what is the reading of the neutron will be if the neutron actually passes in front of a clay zone will it read frosty or not let&#39;s just go back and find out the neutron tool measures the hydrogen component forget about the porosity the neutron is measuring hydrogen component does the clay have hydrogen yes because clay has h2o and clays have oh okay so clays have h2o and we have oh both have hydrogen that&#39;s why in front of the clay the neutron tool will read very high why because the neutron 2 responds to hydrogen and clays they have a lot of hydrogen okay how about the anhydride is there any hydrogen in the hydrides for composition no iron sulfate doesn&#39;t have any hydrogen in it okay how about the soil well in acl there is no hydrogen so in front of the anhydride and in front of the soil the neutron tool should read very close to zero okay so it should not read any porosity whatsoever to my expectation that if it hits the soul or it hits the anhydride it should read zero because there is no hydrogen in there remember neutron 2 responds to hydrogen as an engineer but i need to you need to think like an engineer as an engineer you need to find out does this mineral have hydrogen no or yes if it has hydrogen neutron tool will read processing if it doesn&#39;t neutron tool will read zero very simple okay now if it goes back to clay it will read high how about the sandstone it depends on the prostate if it has five percent porosity it will need less protein is first if it has 25 percent procedure eyebrows so in sandstone it depends on the frost however it goes back to anhydrous that doesn&#39;t have any height and this has to eat zero how about the limestone again it depends on porosity how about it depends on us how about that it&#39;s very high how about the anhydride it is very low absolute zero so my expectation is here is the neutron 2 it will read high porosity here is the 45 to read high porosity in front of place when it goes to anhydride and salt it will read zero okay no hydrogen in there it will read now it goes to the clay again here it will read high cross goes to sandstone it can really die it depends on how much porosity they have but once it sees the anhydride it goes back to zero why android doesn&#39;t have any thrust limestone it will read high profile dolomites very high price in front of clay drops down to zero in front of one i hope that you guys understand now how how these things are related to each other okay how about the density density will do the same okay go for density 2.95 to 1.95 and it will go this way what is the density of clays it needs to place 2.6 2.7 so it will read something similar to this density how about the density of anhydride very heavy and hydride has a very height is 2.98 so that&#39;s why it goes all the way to the right two point nine five here and exceeded about the stool so it is about 2.1 so it goes back to 2.1 okay close to 2.1 and so on so knowing knowing the understanding of what each tool will respond to i can predict what the from this point on what i want you to to get out of this comparison or this analysis i&#39;m doing here is one thing first of all if i see the neutron look at this and keep this in your mind if i see the neutron going going to the left and i see the density going to the right with a separation that&#39;s exactly a clay zone so the clay zone has two properties the first one the gamma ray is hard second one is neutron and density are separated where neutron is in the left and density is going to the right once i see the neutron to the density to the right and the gamma ray is high you can stamp on this zone it&#39;s a clay zone okay now go to the sand sand is opposite of the clay look at this clay was neutron to the left and density to the right when it&#39;s actually opposite where the density is to the left and the neutron to the right gamma ray is not very high like the clay that&#39;s a sandstone response so again what is the sandstone response neutron density to the left neutron to the right again density left neutron right that&#39;s the sandy stone if it&#39;s actually neutral lift and density right that&#39;s a clay okay now if i go here we are overlaying no separation that&#39;s a limestone if the neutron and the density are not separated it&#39;s a limestone so when the neutral and the density are overlaying you can stand there that&#39;s a limestone when they separate similar to the clay look at the clay clay neutral lift and density rod here is neutral lift and density right then if the clay is the same as no clay has another thing gamma ray is high but dolomite no gamma rays should not be that high because it&#39;s a reservoir okay so when i see gamma ray is low and the separation is similar to the clay separation that&#39;s another one okay guys and probably this is the first time to hear this but i wouldn&#39;t want you to at least if you get out of this webinar with this understand look at this when gamma ray is high okay and neutron to the left density to the right that&#39;s a clay signature when the gamma ray is low and the opposite happen density to the left neutral to the right that&#39;s a sandstone signature when gamma ray is low and the and the density are overlaying that&#39;s a limestone signature okay when the density is on the uh neutron is left density is similar to the clay but the gamma ray is low i hope this is actually clear to everyone let me apply this to a to this example i have neutron and i have density here okay everybody everyone can see that i have neutron and have density look at this here is my neutron to the left density to the right how can i identify the glaze i said high gamma interest then neutron lift and density right this is the signature let&#39;s look at the here gamma rays high here is high gallery is the neutron lift yes the neutron is left is the density right yes the density is right so this stone has to be a clay zone how about this one gamma rays are look at this and if i go there uh you know neutron is left density is neutron always is blue neutron is left density is right then this is a clay zone if i go to this peak i gamma ray i go there neutron is left density is russia this is a clay zone again high gamma ray high gamma ray very high gamma ray then i can actually say all these zones are clay zones here is a clay zone here is a clay zone here is a clay zone here is the collision and so on so the clay zones they have i gamma ray we have neutron lift and density okay resistivity has to be low as well why because all these plays are very conductive so sympathy is glorious activities glory sensitivity is gone it&#39;s just a confirmation i always confirm this with my eyes that these are plays clayson okay now the non clay zone we said gamma ray has to be low lower than lower than the glaze now if the neutron is right and the density is left opposite to the clay we call this what we call this sandisk let&#39;s just look at this it is a lower gamma ray compared to the decline here is the clay zone it is a lower gamma rays here is the opposite look at this neutron here who&#39;s left density is actually changed the density is left and the neutron is right so i actually know for sure that this zone is sandisk okay similarly this zone is sandy stone this is only sandy stone and so on so i can actually they say this the neutron here is is essential if the overlay it&#39;s limestone if they actually have the same separation like the the the clay it&#39;s dolomite so applying these rules this reservoir is absolutely ascendant so by visualization i knew this reservoir is a sandstone reservoir okay everybody understand that it&#39;s very very important to train your eyes i&#39;m not sure if you guys uh study this at your at your universities or not but we teach this at the american university here we actually get the students to pick all these zones by their visualization before even using the software so you get trained on how to identify the different mythology from the actual logging date okay how can i calculate the clay volume and the porosity to calculate the clay volume first of all we need to identify what is the minimum clay reading in my reservoir you go there and search for the minimum play reading here is my minimum play reading i decide what is your minimum clarity also go and find the maximum clarity so you put your gamma ray between minimum and maximum okay once you define the minimum and you find the maximum then you calculate the clay volume from the very well-known linear clay correlation gamma ray minus gamma-ray clean divided by gamma-ray shale minus gamma-ray clean or we can call it gamma-ray minus gamma membrane minimum divided by gamma-ray maximum minus gamma ray you apply this on the entire world then you calculate the clay form so how can i calculate the clay volume first of all you look at the logs you decide what is the minimum reading of gamma ray and what is the maximum reading of gamma ray the minimum readable memory you call it gamma ray key maximum reading of gamma ray you call it gamma ray shape okay then you start using these two values to calculate the clay point okay once you calculate the clay volume you plot it from zero to one one is a hundred percent zero is a zero percent now i calculated this and here is my weak layer i calculated my declare as using the gamma the equation gamma ray minus gamma ray minimum divided by gamma and maximum minus governing okay now we need to shade the clay so now shaded the clay here so now i i know exactly my clay volume where and how much do i have at every point once you calculate the declare volume then we need to calculate process we said to calculate porosity first you calculate density process then you calculate the average neutron density process remember this is very very important how can i calculate the density porosity easy your row bulk the density that you calculated minus 2.71 divided by 1 minus 2.71 don&#39;t change the 2.71 because somebody will say you just told us that it&#39;s sandstone and sandstone is 2.65 actually this is true but remember your neutron porosity is on limestone you cannot put the neutron pressure on limestone and you calculate the density process on the sandy stone that&#39;s and that&#39;s it&#39;s not this that&#39;s what you call the bias that&#39;s not that should not do that but since your neutron is in limestone then your density porosity has to be also on limestone for consistency okay the average will take a we&#39;ll take will take the the all this ambiguity out that&#39;s why we average both neither the neutron is correct neither the density is correct the average neutron density is the correct okay to calculate the average by com by adding the free neutron plus feed density divided by okay so the feed density guys you have to use the 2.71 despite that we just identified that the rock is sandy stone it doesn&#39;t matter you still use the you still use the uh limestone density because your neutron is on limestone escape somebody will say well in my country we don&#39;t use limestone scale we use sandstone so in this case you use 2.65 if your neutron is online stony scale use 2.71 if your neutron is on sandstone scale sometimes in the us for example you use sandstone scale 1.65 2.65 so in this case you have to calculate density prosthesis then you take an average neutron density process okay now once you calculated the average nutrient density process you need to correct it for the clay how can i correct it for the clay we call it effective it&#39;s actually the neutron density average minus we clay times p hundred percent clay what&#39;s a few hundred percent clay it is the reading of the clay of the neutron density in front of the hundred percent clay look at your log you go back to your logs it again and you look at the high gamma ray zone which is 100 clay and read the neutron and density prostate there so this is what you call the hundred percent clay point so the neutron density minus clay volume that you just calculated multiplied by the velocity of a hundred percent clay you have a zone in your new log it&#39;s a hundred percent clay zone that you identify okay which is the zone that has the maximum gamma ray reading look at the neutron density there and read the value this is the value of the hundred percent clay point once you do this then you calculate so this is actually read the neutron density in front of the hundred percent clay volume this is the value there so you calculated the neutron density process already you calculated the weakly and you find this from the load you go to the maximum value of gamma ray and read the neutron density in front of it so this is the reading of the neutron density in front of the hundred percent clay and you do the calculation to calculate the expected for us the new plot so here is my effective process okay my expectation is in front of a very high gamma ray i don&#39;t have really effective for us my clay is hurting my prostate it actually going back to zero okay if i look at look at this here are very high gamma ray streak what happened to my porosity destroyed zero here is the high gamma ray streak how what happened my prostate zero it is a hundred percent clay what happened to my prostate zero okay so once i have this it&#39;s clear now in front of a hundred percent clay by reading it has to be zero very very low effective for us okay then here is my clay volume here is my process what is the rest this is my lithology my rock and we identified the rock as ascen okay we said that this is only sandstone we just looked at this it&#39;s a sand stone now we can actually look at it as a sand stone and your lithology is a sandy stone so i know now here is my clay volume my little sandstone and here is my here is my crust so i calculated my effective prostate i calculated my clay volume and i knew my reservoir is sandy stone so i actually came up with that very interesting picture of a very quick analysis i did not calculate how much water or how much hydrocarbon yet so that&#39;s the next step what&#39;s left is how much water and how much hydrocarbon do i have in my poor space sw and sh is a hydrocarbon for simplicity use rc in this case because this is remember this is a quick look when you go back to the office if archie is too simplistic for this reservoir use a different model but at least for the quick look you can calculate rc very very straightforward are she here i have to know what is rw i have to know what&#39;s a m and n for sure in your reservoir these parameters are known once you know these parameters and you calculated your porosity you measured your resistivity then you can easily calculate calculate the step once you calculated this w if you multiply this w times the porosity it gives you the the part of the force that actually contains water it is established assume it&#39;s w it&#39;s 40 and you have 10 pu this means that four pu are filled with water and six pu are filled with with hydrocarb okay that&#39;s what 40 percent mean 40 water saturation means out of the 10 pu that you have four pu are filled with water and six few are filled with hydrocarbons so you multiply sw by the porosity gives you the volume of the four space that&#39;s actually filled filled with water and you put this and you and you draw this and you and you and you color it as blue because blue in our coloring moves means water so this is blue about the rest if this is this part is blue is blue which is water and then the rest will be will be the hydrocarbon we should put it as as green so my hydrocarbon will be as so as you can see here i calculated my hydrocarbon volume and i calculated my water volume with a very very quick way of calculation it&#39;s not really very difficult it&#39;s very straightforward okay calculating your clay volume calculating your effective porosity and then you calculate your hydrocarbon saturation very quickly you can do that on the radio if you are if you actually visit the legs you can go and do this on the leg and you can make a decision which zone i need to perforate which is what i need to complete or this world doesn&#39;t have any potential so you can actually have this quick look in your mind by doing very very simple calculations until you go back to the others and then you start doing more complex analysis that fits your reservoir modeling as you do in the in the company that the journal would be would be working so in summary to have a quick look well evaluation then what you do to perform the following you do environmentally corrected logs then you do a quick look visual lithology determination then you do clay volume calculations then you go for density porosity calculation then you go for neutron density average frosty calculation then you correct that to go for effective porosity correct clay corrected neutron this will affect the porosity then you calculate the water saturation using then you end up with knowing which zone it has the potential of being a producing zone or not thank you very much actually hope that you guys uh learned something from this webinar and i&#39;ll be very happy to entertain some of the questions dr mustafa thank you very much for the amazing uh webinar as usual i have a few questions for you the first question um can we rely on the measurement of the density log in the casing section in the case the section he means it seems like he&#39;s asking about cased whole logging okay no there is no no measurement of density in casing okay what we actually covered here is open hole analysis case the whole we don&#39;t we have neutrons through casing but we do not have density suitcase quite frankly when i was with halliburton before there was big project on trying to find a tool that can measure density behind casing i don&#39;t think it&#39;s successful and i don&#39;t think there&#39;s any company that can do that it&#39;s very complicated as is in neutrons it&#39;s very complicated as is even in the gamma ray corrections so having a density measurement that has very very high sensitivity to any type of uh variation in the wool board if you put the casing and you put the cement also add it will add much more difficulty for the density up to my knowledge there is no density through casing anyway a second question about gulf of sways in egypt to what extent the geological column of gulf of swayze is valid also is it different from another area in egypt absolutely god for sources are one of the most complicated you will ever face if you work in the gulf of south it&#39;s really very complicated it&#39;s different than the eastern desert different than the western desert completely different if you if you can find your way in in the gulf of waste believe me or not you would be an excellent petrol physicist because the challenges there are very very challenges in drilling challenges in evaluation lots of falls lots of uh anhydride lots of lots of salt sections which is a highlight very highly intermediate very thin vertically very thin layers uh you know things are you know known on when things happen across crossing the red sea i think it&#39;s caused a lot of issues uh interesting structure so the uh that this is very complicated one fatima is asking about if we have a sandstone formation how we know if it has water or hydrocarbon you have a sense so from how we know it has water we just covered that at the very end once you calculated your effective porosity then all you need to do is to use rc as a simplistic way first use rc uh calculate rc sw multiply and see what this w is the sw above six seventy percent eighty percent that&#39;s bad luck if this w twenty thirty forty percent then then you still have a result another question uh r p e log and p e f are the same what&#39;s the e yellow p e log oh p e and the second one is actually it&#39;s the same one some companies call it p e yes some kind of some companies call it p e photoelectric and some company called pef photoelectric factor it&#39;s the same thing it is it is the same thing it&#39;s just a different different naming but it is essentially the same thing which is z over 10 to the power of 3.6 which is the this is what the p e is so the f is it stands for factor some companies they call it photoelectric some some common is called photoelectric effect but they are both they both are the same another question do we use rc equation for carbonate too you remember when i started talking about talking about this webinar i said this is quick look something that you will actually need an answer now okay if i need an answer now i don&#39;t have a problem doing some approximations okay even if you don&#39;t know what a m and n is go for one two two okay so you can have a very quick one now if this quick one gave me sw as a 10 percent for example well probably the exact one will make it 20. so it&#39;s not going to make a big difference so it&#39;s not going to change from being a hydrocarbon zone to our waters okay so that approximation is not going to do this but if the sw came as 90 well to never be 10 percent if you apply the exact equation it will be still 80 percent 75 percent still i would still a with zone okay so my point is if you go for on she as a quick look analysis quick look and i stressed on this at the beginning this is a quick look a decision i need to do now i don&#39;t have enough time to leave the rig there that&#39;s costing me a hundred thousand dollars per day for someone to go and wake up and wash his face and sit in front of a computer and take his time to do the analysis and i&#39;m paying money on direct no i need somebody to make a decision now to make sure do i let that be the right release or i need to stay and complete the work then at this time i can use ash once you&#39;re done with this you made your decision when you go back to your office then do whatever sophisticated for you i agree with you archie is not the most suitable for carbonate but as a quick look it is okay for carbonate as a good one another question is it possible to have mechanical errors in the logging tool and how we can find out that mechanical one mechanical errors you mean by mechanical errors mean mechanical tool errors yeah it seems like something wrong with equipment itself for sure but the but the field engineer will find this out easy and any trained engineer will will be able to find if there is anything in the connectivity between tools it&#39;s not clear what the question is but anyways if you if this is what he means a very well-trained engineer would be able to find this the last question uh is it possible to have the slides uh unfortunately unfortunately you know but you will have a webinar you can watch it as much as you want okay dr mustafa thank you very much and please enjoy your rest of the day if you have any rest of today i believe you have evening now so enjoy your evening yeah thank you guys very much appreciate it and look forward to seeing you guys some somewhere in this world okay have a good evening you too bye bye

Transcript for:Understanding Formation Evaluation Techniques

Transcript for:
Understanding Formation Evaluation Techniques