Transcript for:
Hydraulic Fracturing Q&A Session Notes

hello good morning good afternoon and good evening on behalf of petol petol and Military search Hub I'd like to welcome you all in our Q&A session my name is my aror a senior Gaz and petrochemicals engineering student and Egypt young professional member and I'll be your moderator for today so before we start please keep the chat box professional and ethical and don't forget to drop your questions in the Q&A section below so without further Ado let's welcome Dr Ahmed Dr ahmedi is a distinguished professional with over 20 years of experience in the energy and petroleum industry specializing in production enhancement services Dr ahmed's expertise includes acidizing fracture hydraulic fracturing J mechanics to thermal energy carbon capture utilization of storage and hydrogen Technologies Dr Ahmed has successfully LED projects for major companies like Apache CH PP shell and totel currently Dr Ahmed a research manager at military search Hub he has a proven track record in publishing applications in energy uh on machine learning his academic tenure as an assistant professor at Marita College underscores his deep knowledge in production enhancement petrop physics and well logging analysis Dr Ahmed holds a PhD and Masters in petroleum engineering from Texas Tech University he has published over 30 research papers and received a distinguished Achievement Award from SB International in 2021 thank you so much Dr Ahmed for coming today and the mic is yours may thank you very much for the introduction uh as we agreed with everybody this course uh planned to be four lectures and lecture number five is questions and answers so uh in my last lecture I asked you to write your own questions below the YouTube videos after we do the lecture we post the video uh the same day on YouTube and I copied your questions um from you know from these videos and today I will try to answer them one by one okay so may if you want to help me reading questions yes is there a natur way of increasing formation permeability with necessarily using any of the simulation enhancing techniques guys um this is a very good comment or a very good question but remember um all the time think about the original state of the reservoir the original permeability of the reservoir there's two important paramal you need to understand very very well uh number one is a porosity we we are talking about sedentary Rock has organic content has maybe oil or gas and this rock should have a pro good Pro good Pro something let's say 5% 10% 20% so we expect something what we call it good porosity let's say if we are talking about conventional Reservoir like a Sandstone formation or Limestone formation or dite formation for example something between 10 to 25% I will call this very good for us okay this is the storage ability of my U uh Reservoir okay if I'm talking about tight sand or I'm talking about organic sh Shell gas or Shell Oil um I'm expecting most likely something less than 10% pososi 5% 7% most likely we are talking about numbers less than 10% okay so um the second important parameter what you call the permeability the movability of these fluids which is maybe water maybe oil maybe gas how easy these fluids can move from a place to a different place inside the res okay we call this the permeability a parameter describes how easy the fluid can FL flow inside the reservoir okay so before any formation damage before any fracking before any acid or before any formation damage because of the drilling of fluids or completion fluids or whatever okay we call this this is the original state of the reservoir this is the original permeability let's say it was 5 m for example okay so there is no natural way to improve to enhance um permeability without doing something to the reservoir you cannot say I will leave the reservoir for 10 days or 100 day and after that the permeability will improve you need to do something to improve the permability something like what something like you may do hydraulic fracturing remember even if I'm saying doing hydraulic fracturing to improve formability this is a wrong statement hydraulic fracturing is not improving the permeability hydraulic fracturing by passing the formation damage so what is improving permeability acidizing May improve permeability acidizing May improve permability okay so if you have a limestone formation and this lione formation you do Matrix acidizing or acid fra now you are improving you are trying to improve the permeability of the near WB region okay but if you are doing hydraulic fraction You Are by passing the damage you are trying to make like a highway to cross the damage but you are not fixing the damage so so when you say hydraulic fracturing improve permeability of the reservoir this is the wrong statement acidizing improve the permeability yes possible possible okay I I I I wish I hope this is um clear to everybody that there is no way to improve permability without doing anything just you leave it for nature and the permability will improve uh in a very short period of time in a month or a year without doing anything this will not happen okay maybe over millions years maybe a chemical reaction happen inside the reservoir so the permability will change over millions of years but this is not your question you are asking about something in a short period of time so in a short period of time if you want to improve permability number one you need to study the chemical composition of your Reservoir what is the minerals in this formation is it limestone is it dite is it Sandstone is it Shale what type of shale and based on that you decide what should be the right treatment to do what is the right chemical treatment what is the right asset to do to improve permeability One Last Time hydraulic fracturing is not improving pability hydraulic fracturing by passing the formation Dage if you are talking about acid Frack you're doing Frack using acid like HCL in a limestone Reservoir or dite Reservoir now you are creating a fraction using acid and at the same time you are doing something called itching for the two faces of the fracture and also you are improving uh permeability for the near B region near the fracture at the same time you are dissolving the formation damage if that acid you are using chemically can dissolve the formation damage and the products of that chemical reaction is soluble in water okay so I hope uh this is clear to everybody let's go to the next question can you explain the treatment fluid part please I didn't get it clearly okay so simply when when we talk about hydraulic fraction if or if I want to ask you you what is hydraulic fracturing hydraulic fracturing is using a fra fluid or using a fluid we call it engineered fluid engineered fluid because it is designed fluid I will not go get any water and injected I would get I would go get a special water meet meeting a specific uh specs specifications okay I will add some additive so I will Design the FR fluid okay to meet physical and chemical properties okay and I will inject it in my well and when it goes to the through the perforation I will pump it and try to build high pressure enough to break down the resle okay so that fluid I'm using I may use slick water just fresh water and a friction reducer this is if I'm trying to Frack a brittle shade so brittle shell the best choice as a FR fluid is to use something we call slick water and the slick water is just water and fraction reducer okay if there's any minor additives but this is the m the two main uh uh things we are using in slick water and conventional Reservoir such as conventional Sandstone formation if you are using slick water the slick water will leak immediately the permability a little bit high of the conventional Sandstone so you cannot build a net pressure inside the fracture you cannot keep the fracture growing to take the dimensions you want okay so to do this you need to improve the viscosity of the fluid you need to make the that fluid uh more viscous okay a viscous fluid we are using what we call Crosslink gel we are preparing a linear gel something like milk in you know the shape of the milk then we add a chemical to it make it looks like jello and I'm using that jell to uh transport the pent from the surface and inject it inside the fracture and distribute this propin in a good distribution inside the fracture okay so that frag fluid is a complex recipe the same like you are in the kitchen trying to um you watch uh a cook in in the TV trying to make a special food or a new food something you don't know and he asked you she asked you to bring a list of ingredients and now you are in the kitchen trying to make that food okay so we call it a recipe okay the recipe this is the last of instructions you need to do to um create the track fluid so you may add for sure you will add water and for sure you will add propen for sure you will add some SE V you would add KCl you would add jilling agent you would add scale inhibitor you would add uh pH adjusting agent you'll add breaker so there's a long list of additives we add and each additive do something okay for sure the first time you will see all this list of additives you may get confused this is too much but trust me if this is your job if your job is a FR engineer within one month you will remember everything about fraction again I always tell my my student to be a good Frack engineer maybe you need something like six months if you are a mechanical engineer if you are a chemical engineer if you are Industrial Engineer if you are a civil engineer and you go for a training to be a good Frack engineer maybe you need something like six months to be good good uh frat engineer to start your career I will not say you will be an expert because you still lack experience but you can do the major uh uh required uh job okay so uh I hope this is uh clear let's jump to the next one so um uh why do we need to keep the injection rate constant all through okay so this is a very good push but please to ask a question like this I want you first to watch the four lectures because sometimes I answer the question during the lecture and if you did not watch that qu the lecture you will uh you will not understand why okay and and again we we were not planning to make this sis we it was just planned to be a four lectures and that's it so when you do hydraulic fractioning after you do the job again you are designing a frag job and my design will be different uh if I'm comparing my design with my design with your design and we will make three or five different designs all of them possible all of them to be right no problem all of them will do their required job it is like you are designing a house it is not one one answer it is not one solution okay you need to make a design to create a hydraulic fracture in a good shape in a good Dimension and you place a Popin and a good distribution inside that fraction and for sure you respect and learn from the best practice of the experts working in your company and other companies okay so after you finish the job you need to evaluate the job you did how I will evaluate the design you did if it is good or not after we take your design go and implement it in the field we need to have a way to evaluate the design you did okay so I will do some will testing uh right after stop injection to understand the lick off to uh to get the closure of pressure and after that also I can uh do some World testing to understand the permeability and understand the res pressure okay so to have models to evaluate postive frag what we you know to evaluate the the FR job we have something like the G function technique in my uh in in my third lecture I'm not sure if it is a second third but maybe the third lecture I talked about the J function it is a mathematical model to evaluate the leak off also I with the leak off I can get the closure P okay so the leak off Behavior and the closure pressure that mathematical model for example has assumption that the injection rate was constant it means if you cannot keep the injection rate constant you cannot use the J function technique to evaluate your fact you got what I mean so the techniques we are using to evaluate the frag job after doing the treatment after injecting the treatment one of the assumptions that the injection rate was constant so you need to keep it constant so you can use that mathematical uh technique to get the closure pressure and to get the to understand the off okay and I believe in lecture in the third lecture I explained that but uh thank you anyway for the question because this is very very good question let's go for the next one okay so this is a comment get from a student saying that he or she cannot understand English and this is why he cannot benefit from the lectures here is a point listen carefully if you decide to work in the oil and gas business and you will get a job you get a job in ADN in Emirates or you get a job with Saudi AR in Saudi or you get a job with Apache in Egypt or you get a job with toel somewhere okay you will find most of the countries that has o and gas business they are using English as a official language you have a colleague from India and you are from Egypt you are from Algeria and your colleague sitting beside you from China you will not talk to him in Chinese or or you will not use Indian language or you will not use your Arabic language okay you need to have something in common to use to communicate something to use to write an email okay so over a long time we use English to communicate in the oil and gas business back when I was working in Egypt during the uh if you are working for Apache for example you have some colleagues coming from United States they don't know how to speak Arabic they don't understand Arabic so you to communicate with them you need to speak to them in English you need to write them in English okay if you work here in the United States like what I'm doing I have a colleague from Nepal I have colleague from Bangladesh I have a colleague from Ethiopia I have a colleague from China how we will communicate with each other so we use English to communicate so please remember this if your English is not good it means your job is to work hard to make it good as possible find a way to improve and enhance your English get classes watch American movies get a training course whatever you will do but in a in a very short period of time let's say within one year you need to fix this problem okay also my advice watch the video many times and you can use a translation the on time translation by the YouTube and it can translate uh to the art language but please try um within 10 month months or a year to improve your English Okay so may let's go to the next question okay the pH of frag fluid is usually less than seven true FS okay so this is a very good question but let me ask you first please write me in the chat any example for a fluid you are using in the oil and gas business let's say Frack fluid drilling fluid completion fluid killing fluid okay L all examples you may think about all fluts we are using to drill a well or to let's say the cement we are using the hydraulic fraction we we are doing all of them the pH must be more than seven except you are doing acidizing remember this because I get many questions about this and it seems like you are confused about okay any fluid you are using in the O gas business to drill so this the drilling fluid you are using the pH more than seven the cement the pH more than seven the completion fluid The Killing fluid the pH more than seven the frag fluid the pH more than seven except when you do acidizing because by definition if you are using HCL or organic acid or whatever acid the pH will be less than seven more than seven this is alkaline less than seven this is uh acid and seven this is neutral like water Okay so remember all the fluids we are using greater than seven except when you do acidizing of acid fra that's it acidizing of acid FRA the pH will be less than seven okay the second part of the question why because I am injecting let's say I'm using a production tube or frag tube or whatever I have casing I have a tube I have all all these things most of them made out of uh steel Alloys and corrosion is a big problem so to minimize the chances for corrosion it is better to use something not acidic if you're using something alkaline you are minimizing the chances for corrosion okay because uh this question many of you get it wrong and many of you what has like um the opposite belief okay so I hope now it is um you have the right information now okay let's jump to the next one during hydraulic fracturing do we pump the fluid through the production tubing or through coil tuing okay so as a completion as a completion engineer when you decide to implement a fra job you design for it let's say I have a Sandstone Reservoir in the western desert in Egypt or somewhere in Algeria in m in in Algeria for example okay and let's say I have a Sandstone for me and I have a vertical one or slanted one so you you may use a production tube or just you know a cube 3.5 in something like that you can use it to Frack the formation so you have the tube you have a packer and you set the Packer right at the top of the perforation and you can test that the Packer is is okay and everything the backside pressure is constant stay constant and you can do your job do the the fure okay what if if you have a horizontal well and it is open po completion there is no casing at the production section and it is carbonate formation also in the western desert in Egypt ab area we have something like that and Emirates in in in the uh Gulf area in the Middle East we have many carbonate formations okay and uh you decided oh it seems like if I if I will use a coil tube and do acid frack and I will inject acid and a pressure higher than The Parting pressure of the formation and I will do multi-stage acid Frack so maybe it is better to use a coil tube so using a coil tube or using a tube this is your decision and this is your design how you do it you do it based on your experience if you don't have enough experience you follow what is the expert and your company used to do or you um uh you you learn about what is neighbor companies doing okay but the answer for this question we do both based on the the case I will decide Accord tube is better or using uh a production tube is better okay but you can do both okay let's go to the next question please clarify after submitting the assignment what do we have to do any attachment or mark it is it has work done till now no clear guidance there is clear guidance come on what you need to do number one you do your best to attend the zoom meeting Sor do your best to attend them Zoom let's say you have something more important you have emergency the time was not good for you so wait and watch the video on YouTube at least one time when you watch the video try to take notes don't say I'm just watching you're having uh sum of training to learn so you cannot learn without writing notes by the way when I when I when I used to go to the field when I was working with Apache or even here in the United States all the time and my cover all I have in my pocket I have a note and I have a a pen and whenever I learn something new I write it down because if I will not write it down for sure the second day I will forgot this is nature so try to write notes when you watch my video or other uh professors or expert videos try to write notes this will help you to learn faster okay after you write your notes and you watch the video and you get the feeling that you already understand the topic and you understand the lecture go and do the quiz if you do a quiz and you get confused about one or two question questions you may do your own search on Google all of them are easy questions but maybe just because you are new to the topic but if you check Google or you you will find uh explanation for for any question okay and um after that just you wait you submit your request on time the answer on time and you wait after we finish the course because within 10 days we will make make a final exam for that course then you'll receive your certificate and we use many of the questions we use in the in your quiz so this is why we don't want to share the answers with you early because you may see this questions again in your final exam okay but you know I just try to attend Zoom watch video take notes do the quiz and wait for the final exam that subject okay next question please why is the pH of rack fluids greater than seven I don't understand we already I already explained this mainly to avoid any chances for corrosion we use a lot of corrosion Inhibitors and you know I just to uh try to um uh EX the life of the tubing amusing we are trying to save this tubing to to live for longer time okay so um uh keeping the pH uh higher than seven especially because I'm using a lot of water so uh by doing this I will minimize the chances of collusion in the system so this is why we we are trying to keep it above seven next question why are there a okay so you you're your voice your the connection was not good in your side so I will read the question from my side why are there a lot of equations for converting dynamic to static youngest models I will tell you what let's say I'm walking I I live in Ohio and I live close to a Shale play called Marcela sh Marcela Shale you know like um 100 mile away from my home like in Pennsylvania for example and and West Virginia okay and I developed a correlation to convert Dynamic canus models to static K models in marcelis Shale area in Pennsylvania and West Virginia and Ohio and North uh of New York do you think you can copy this equation I developed here for a specific location and apply it in the Gulf area and the Middle East write me in the chat yes or no do you think you can use that correlation to convert Dynamic to static youngest models developed for Marc shade or Gulf of Mexico for example here in North America and use it in the western desert in Egypt or use it in Algeria or Libya for example or use it in Iran or use it in India do you think this is something right to do no the Earth is not the same the formation is not the same there is no identical reservoir on Earth you will not find two reservoirs there's some similarity but they will not be identical okay so you need to develop your own local correlation for a specific Reser you are working in Saudi in a specific place in Saudi you need to develop uh a correlation to conver Dynamic to static modelist developed for that place and you cannot take this equation and apply it in Gulf of Mexico or apply it in Latin America for example you cannot do that this would be a big mistake okay this is why if you ask someone less correlations to convert Dynamic to static Ang models he can list 1,000 correlation or 10,000 correlation why anyone working anywhere can develop a local correlation so but you cannot use uh most of them if if they are not developed for the same place you are interested in you cannot use them so the conclusion you need to develop your own local correlation to convert Dynamic to sta models in the reservoir are working on or in the field you are working on okay let's go for the next question why is the fracture Direction perpendicular to the minimum stress Direction okay so I need some imagination because you know I'm uh it is better to to show you a picture but because I I I I did not prepare a picture so please I need good imagination with me okay we agreed that let me use U okay so I have a picture at the end and I when when when we go to the end I will explain it one more time so we have three principle stresses we are using three principal stresses I'm using the overburden which is vertical and I'm using two horizontal stresses the higher in magnitude I call it the maximum horizontal stress and the lower in magnitude I call it the minimum hor stress okay so let's imagine that the overburden has the highest magnitude so the magnitude of the over burden is the highest and the second is the maximum horizontal stress and the third in magnitude is the minimum horizontal stress okay if you are planning to break one of them which one is easier to break write me in the chat in this scenario which one is easier to break the minimum horizontal stress or the maximum horizontal stress or the overburden and remember the overburden is the highest in magnitude which one is easier for you to break so I get two answers one one wrote I will break the maximum and one wrote I will break the minimum guys breaking the minimum is is easy because he his value is small if you have someone strong and someone weak and I'm asking you to fight with both of them which one you will you will choose you will choose the the weaker one because you can beat the weaker one easily right so you will break the minimum horizontal stress so when you open a fracture when you open a fracture against the minimum horizontal stress you will see the fracture growing perpendicular to that direction when you open a fraction against the minimum horizontal stress you will see the fracture growing perpendicular to the minimum horizontal stress Direction in that case some people say oh it grow with the maximum horizontal stress because also the maximum is perpendicular to the minimum but remember the right thing to say the right answer the perfect answer the fracture will grow perpendicular to the least stress if the least stress is the minimum stress so it will be perpendicular to that if the least stress will be the overburden so the fracture will be horizontal and it will be perpendicular to the overburden in that case Okay so why the direction is perpendicular to the minimum because simply you are opening a fracture against the minimum you are beating the minimum so your fracture open and you see it growing with a direction perpendicular to okay I hope uh this was clear my my apology is that I did not show you a picture you know it is better to use a picture present next question how can we check the results of acidizing and hydraulic fracturing in the real time okay this is interesting question but trust me there is no way to evaluate the permeability change of the let's say the the the stimulation Improvement because acidizing change permability but the fracturing is creating a new high conductive uh pathway which is a fracture itself so the technique of improving production is different from comparing acidizing with with h fracturing the techniques are different but both of them they are improving productivity but we what we can say there is no way to see this uh production enhancement on time we evaluate what happened after the fraction after you finish the job after you finish the acidizing job you can evaluate after you finish the hyic FR job you can evaluate after you finish the acid frag job you can evaluate but during the job itself there is no way to see the change or the Improvement okay only what you can do is to do some simulations but you remember simulations are just simulation so uh a simulation software this is a way to um a design a design tool okay but there's no guarantee that what you see in the design or in your software maybe will be like a 70% % agreement with a final result or 60% agreement with a final result so there is no guarantee that what you see in the simulation this is exactly what you will see in in in the implementation most likely if you have a software can get you 75% of what what would happen I would call this this is a good software okay so to conclude or to summarize just there is no way to see the production enhancement during the job itself the maximum what we can do is just simulations and simulation this is just matical models and you know um a lot of assumptions so there is no guarantees that this is exactly what is going on okay all what we do after we finish the job after we stop pumping we do what we call Post Frack evaluation or post acid evaluation post acid frack okay next question when we perform bu test after a successful hydraulic fracture is it correct to expect to interpret a higher permability than a bu test performed before HF okay so bu he mean buildup test okay and HF just has a hydraulic faction okay so he's using like a you know short names okay so for sure if you will do a buildup test before doing a hydraulic FR job to evaluate the permeability and evaluate the skin you have you to evaluate the formation damage you have and evaluate the probability for sure if you will do a good design for a frag job and after you do the FR job and you start evaluating let's say the the permeability or to evaluate the uh production for sure you will get a higher production if you do it right okay but remember one more time look to the specture in the middle this is the whe board and the bed this is a formation damage okay we call it the damaged Zone and the green we call this this is the invaded Zone it is also damaged but you know less damage okay look to the hydraulic fracture the hydraulic fracture not fixing the damage not removing the damage it is bypassing the damage it is creating a new conductive surface connecting the reservoir with the w if you remember in my first one or two questions I told you hyd not removing damage not fixing damage it is bypassing damage bypassing damage like a jump jump the damage skip the damage the damage as it is in the formation but he creates like a highway and use the highway to to collect the hydrocarbon and water and all the fluids from the reservoir to the uh WB okay what is fixing the damage or what is removing the damage most likely acidize but you need to check the chemistry first if the chemical you are using or the acid you are using can dissolve that damage or not this is a question you need to answer first to select the right chemical of the right acid system so it can dissolve the damage and the result of that chemical reaction will be soluble on water so you can produce it produce that uh solution back to the W Bo during the early production period after you finish the JW okay so evaluating the permeability after the frag I'm not changing the pability of the formation I'm not changing the formation damage I'm not removing the formation damage but after the buildup test if you if you if you do build up test before the Frack before the frag job you will find uh productivity less than what we get after F but the permability will stay as it is the pability of the reservoir will not change okay also to um uh make it easy to to um remember hydraulic fractioning improve productivity for few reasons number one hydraulic fracturing increase the contact area between the fracture between the reservoir and the wpol by fraction so increasing contact area between the reservoir and will this is number one number two is by passing the formation damage by passing by passing The Crowd surrounding the WBO that stop the production or stop the the fluids from flowing okay by creating a very conductive new Surface using the Pent the pent that keep the fuction open okay so this is why facturing improve productivity but you will not find in the list anything about removing damage or dissolving damage fracturing will not do that except you are talking about asset track up and out and the acid you are using can dissolve that um per tap in the formation that's making the damage next question I checked the quiz in Google classroom and I saw some questions about certain ad additives and these additives haven't been mentioned yet so do we wait till the fourth lect and then do the quiz please when you see an additive or something you did not get in the lecture try to do your own quick search about if you see a question about breaker and we we I didn't tell you what is a breaker do all what you need to do go to Google and write what is a function of breaker in hydraulic faction you will find many resources give you a very simple explanation so I totally understand that yes maybe some questions you did not get uh clear explanation for it but um trust me they are simple ones do your own quick search try to get the answer after the quick search and solve the qu solve the question and submit it next question I would like to know the difference between pad volume and clean volume okay so the pad volume the pad volume is the volume we inject at the beginning of the fractioning treatment we start with it it is a frag fluid without any propin in it Frack fluid at the beginning of the treatment without any prop in it and its function is to break down the formation create or initiate the fracture in a good shape so the fracture can accept poent coming after the pad if you start without a pad if you if you do the cracking without any pad volume you will get early screen out immediately you cannot grow your faction okay so the P volume is a fact fluid without po we injected at the beginning of the fact job okay the clean volume is the total volume of all fluids are used without propen in it including the pad so clean volume the opposite of clean volume is a dirty volume dirty volume this is called the volume of f fluids including prop in it has a prop in it when you when you see it you'll find it gray has a gray color because of the pur in it the clean volume is the total volume of fluids injected and has no prop in it the pad volume is the only portion we inject at the beginning without a problem okay next question seems like we are running out of time so Dr Ahmed I have a question what is the role of chemical engineer in the in the hydraulic fracturing okay all the F fluids so let's say what is the role of chemical engineering and production enhancement General okay when we talk about Frack fluids and you see a long list of additives of chemical additives okay and you need to invent new additives to do the same function for example if you want to use a chemical to dissolve scale from ASP pump for example or a scale from a tube we are producing or you want to in find a chemical let's say to um uh to kill or to prevent sulfur reducing bacteria for example or in acidizing or an acid Frank all these things are chemicals and the best one understand this okay so a chemical engineer has a very important rule in production enhancement in general especially yes evaluating formation damage and um uh fixing formation damage in hydraulic fracturing and acidizing and acid fact all these things has a important role for okay thank you okay next the next question I heard that in uh in your videos their certificate for hydraulic fractioning course one other and The Intern as well I have challenge of attending the zoom meetings because of job schedule but I have watched all the videos and completed the assignment will I get these certificates you mentioned at the end of The Internship okay so all the time we say this do your best to attend Zoom except you have a good reason if you if you if you have a job and your employer don't allow you to watch these videos or in a place that you don't have a good connection go and watch the Youtube videos and try to submit uh the answers for quizzes on time okay do the when we announce for the time for the final exam for specific training let's say after 10 days from today for example I will ask you to do a final exam in the four lectures in the five lectures I explain and I will give you a certificate uh on introduction to yic fracturing class this is part of the training if you attended say 70% of the training we will give you a certificate for the training for the all training together okay so at the end of this training at the end of let's say in August you may receive 10 or more different certificates okay so please do your best to attend uh Zoom except you have a good reason if you have a good reason just text me and Link it in send an email just to uh to make a case that hey I will submit quizzes I will submit the final exam I will watch videos but please I have a walk or I have an emergency and this is why I did not attend at that day or that week okay let's go to the next one it's someone is saying thank you very much for the lecture I'm not I'm not receiving the assignments okay so whenever you see someone writing this it means he don't he or she don't know that we are using uh Google classrooms so we have five Google classrooms and you need to join only one so some of you in classroom number one some of you in classroom number two or three or four or five so so this guy I believe he may he may watch the Youtube he may attended the zoom but he don't know that um after he fill the the application the registration uh application he need to receive a code or a link to join one of the five classrooms we have if he or she join the classroom the Google classroom for sure he will find or she will find the who this Z so please if you don't have one of these five classrooms you need to join or you need to ask how to join one of these classrooms next question Dr Ahmed uh someone is asking in the Q&A um uh a part uh why the minimum skin Factor we can get is about4 not less okay we call this is this is uh practical so let's say you work in the business for 20 years or 40 years or 30 years and you say okay it seems like there is a difference between having an equation or doing something in a book something theoretical okay but after you see hundreds of thousands of cases you start getting your own evaluation for okay so the equation we use let's say to to have let's say uh the permeability let's say after uh sorry the the the skin Factor after fracking or after acidizing okay we notice that we can see a positive 100 or positive 50 or positive 150 it happened but we never found a case that we get less than -4 this is like a a fact okay but because the the correlation of the equation we are using is not perfect so it may give you5 or -6 OR7 but when you see7 on paper and you link this with your own experience you will say okay ne7 this is only on paper this will not happen Okay so just you can say nothing you will not get a skin Factor less than4 because it's seem like this is this is nature or this is uh the physics of Earth over over 100 Year let's say we are developing oil and gas let's say 200 years now 150 years like a long time anyway it is more than 100 Year and we have never we we we never uh seen a skin Factor l or you know after stimulation so we we started hydraulic fracturing in in late 4S let's say starting from 1948 or something like that okay and from that day we never seen any um skin Factor after job or after acid that job or after aiding job went less than minus 4 in in in the real life okay so you can just say it is physics the physics of Earth this is like a nature okay let's go to the next question Dr Ahmed uh there are so many questions saying that they um they submitted the quizzes but they are still shown as missing so is there a problem or they or I just whenever you are sure that you submitted sometimes you get this mistake uh we go and check and we find the quiz there no problem don't worry if you submit it it means that we we receive it even if it chose that they're missing or not submitted or whatever don't worry about it next question is this course only attributed to onshore oil and gas or offshore oil and gas or both okay so um uh when we talk about something like fracturing or acidizing or you know there is some topics there's a big similarity between what we do onore offshore you know for sure you know when when you talk about uh offshore for example we may care about things like uh fren p can you know doing hyic faction for sand control for example not to improve productivity in M cases like in Gulf of Mexico for example but um there is a big similarity between what we do onore and what what we do offshore for sure there's some differences but it is too early uh for you to think about these things now if you talk about drilling you will find very big similarity if you talk about production if you talk about evaluating reservoirs there's a very big uh similarity let's say the drilling gig I'm using in offshore for example in deep water for example you may find the the Tower of the drilling rig for example is like a four pipes okay on land you may find it three pipes to the tower on on the sea if you are dilling in the deep water for example you may find the Tower of the drilling rate is higher but the same components the same technique the same ideas okay uh in this training we ask volunteers to teach but we need to have qualified volunteers so we go on talk to good experts from universities good expert working for you know famous companies and uh their English is clear uh you will not have problems understanding them okay you may get an expert in unsure offsh sure this is based on who's volunteering okay but you know again if you if you're still student don't think don't think about these minor differences just focus and try to learn from all uh lectures as possible next one when having high value leak off isn't desirable but isn't mean that you have a net of fractures inside the formation rather than let us say one long one long fracture and why the second second is one desired okay so uh this is a hard and tough question because there is a a big debate about what is exactly happening inside the formation okay for a long time before developing or you know massively developing Shale when we were just fracking Sandstone formation or Limestone or dite we always think about bwing fracture a fractor that has two Wings going uh or growing in a Direction perpendicular to the minimum stress okay when we started developing Shale and we we get new Concepts new ideas about the fracturing so let's say some one of these ideas when you fracture bitt sh for example using slick water you create something like a complex fracture system or fractal Network let's say you have uh many many cracks going to random directions it is not one fracture two Wings anymore okay we call it complex fracture system or complex fracture or or SRV stimulate stimulated the visable volume okay and this idea was has a lot of supporters but later we start getting debate again no no no no no even in Shale we have by wi factions so there is two groups one group still believe that even in shade we have two Wings fracture and another group believe no no no we get factures thousand of factures going to random directions and and it is better to use a like stimulated res volume or um a concept like complex fractur Network so um I cannot guarantee which group is right and which group is wrong because each group has very famous names and very famous scientists supporting them but all what we can do is we need to learn about both ideas okay so in shap to summarize in Shale if you have Bal formation it is better to use slick water and we expect to get random fractures going everywhere all directions okay if you have less ble or you have ductile Shale I am expecting to have bwing fracture and it is recommended to use slick water or to use a hybrid system like a sorry uh by by Wing factures you you should use uh post link gel okay so high berness formation use slick water less berness or ductile formation use cross link J or hybrid system okay so uh there's a lot of things we still don't understand about Trail uh and I'm I'm I'm telling users to motivate you to work harder as a researcher you may find something and you may uh get better conclusions and we all of us we we can learn from your your research later okay I'm not sure if you like this answer or not but trust me there is no guarantee about what is exactly going on when we talk about shade okay uh one more last thing that all the time when you talk about conventional fracturing when you talk about organic even when you talk about organic shade if you want to create a fracture I want to make the fracture Dimension under control during the fracturing treatment this is why I want control Bak off I don't want to very high lick off I don't want very less lick off because both of them are bad zero lick off is bad very high lick off is bad we need controll lick off so I can keep the net pressure to the value I want or to the range of values I want so I can grow the fracture the dimensions I want okay let's go to the next [Music] one I understand the the idea behind using slick water for tracking non-conventional formation that is pumping fresh water plus friction reducer at very high rates however I was wondering why fracking for conventional Wells has to be the cross Linker Linker gel is there anything else that worse okay the main difference between conventional reservoirs and unconventional reservoirs is the range of permeability if you have very little permeability something by Nano 100 Nano Dary or 500 Nano Dary Nano is like a 10 to power minus n something very very very small okay if you have something by Nano like 100 Nano or 500 Nano for example you um you cannot use um Crosslink gel in that case if you use cross Linker gel it will most likely uh it will be hard to inject it will be hard to inject why because um the leak off will be very very small and you keep balloning the fracture and the the surface injection rate will keep growing very high rapidly very quickly and it is hard to to do the operation okay and because of the permeability very very low so injecting a slick water just water the viscosity very low this will be easier to inject it would be easier to inject sometimes we inject a hybrid system let's say part of the treatment is the slick water and part of the treatment is co link gel but again this is you do this you do this design after fully understanding or understanding as much as possible the formation properties the ability and natur factures and and everything about the formation before you it okay so um um there is good cand so so um uh based on the reservoir based on the understanding the reservoir is it a Sandstone formation the permability is high for examp or if it is tight sand and permability very low So based on understanding the proper of your Reservoir you decide what is the right or what is a good candidate for the Frat fluid to use okay so if the permeability very low most likely High viscous fluid will not work if the if the permability very high or high or in a good range so cross LED gel will be uh your right choice okay remember the fra fluid the main function of it is to break down the formation and carry the prop and place it in a good distribution inside the fracture system you are creating keep this in mind next question what are the key differences between convention Reservoir completion and share res our comp techniques okay so the main difference between conventional and unconventional is the permability so if you have very low permability I will call this unconventional Reservoir if you have tight sand I would call this unconventional if you have C bit mean very tight formation I would call this unconventional if you have um Shell Gas Shell Oil and the permability very low I will call this unconventional okay if you have Sandstone formation and the permeability in a good range let's say 5 m 1 M 10 m I will call this this is conventional why the conventional Reservoir you can produce it using fracking or not fracking if you are not fracking you you you still can produce some of it okay if you D vertical you can produce some of the hydrocarbon okay but for unconventional you cannot produce it economically without doing horizontal drilling and without doing multi-stage fraction you must based on today technology you must do these two horizontal Wells and hydraulic fraction this is for the unconventional if you use S water the formation is veral and you can use the qu this will make it even better and more economic [Music] so conventional or unconventional mainly the main difference is the permeability range okay next question how does the complexity of fractured networks impact the overall productivity and efficiency of the Shale gas and oil wells I think we already answered this uh in Shell gas and Shell Oil assuming the formation is brittle like B sh for example okay when you fracture I'm assuming I'm getting more fractures in random directions so this fracture Network I'm creating by by fracturing will add more ways or more paths for the hydrocarbon for the fluids inside the formation to go through it and get produced go to the W and get produced okay so uh I'm creating this this complex fracture Network by fracturing um this will make the fluids will give the fluids easier ways to reach the w b and get produced and this is how we produce the organic shell and organic gas and the organic shell the Shell gas and Shell Oil by doing hydraulic uh horizontal drilling and doing multistage fuction and using slip water if the formation is BR next question okay let me read this question may you know what um I like this question very much so guys please give me all your attention Okay so one of you wrote me an I believe he he he's not a student he seems like he is an expert and he understand exactly what is the difference between a tenser and a Victor so it seems like he he has some good work experience and he WR very good comment he wrote me stress is a tensor and not a Victor as mentioned in the in the lecture okay so before answering this question or comment on his con okay we need to ask first what is a tensor what is the definition of a tensor and what is a definition of a scaler and what is a definition of uh a vector okay so I get you this definition from University of Cambridge what is expensive okay so may can you read the definition for me is starting from in fact tens SP okay let me read it in fact tensors are merely a generalization of this um scalers and vectors A scaler is a zero rank tension so scaler even a scaler is one of the T so that is a special type of tensor so a scaler is a zero rank tensor okay and a vector is a first rank tensil so I have a zero rank tensor a first rank tensor a second rank tensor a third rank tensor and so on okay the rank of a tensor is defined by the number of directions the number of directions remember this definition uh carefully because I will ask you questions very soon okay the number of directions okay hence the dimensionality of the array requir to describe it so I will ask myself is the thing I'm talking about has a direction or not and how many directions and based on that I will decide what kind of tensor I will describe what kind of T I will describe okay look a scaler write me in the chat a scaler has a direction or not the scaler scalar value has a Direction dire yes or no right in the chat scaler has direction or no scaler is just a magnitude just a value has no Direction okay so scalar is zero Dimension tensor has no Dimension has no uh Direction sorry zero Direction tens what about vector the vector has direction or not the vector has direction or not write in the chat Vector has Direction yes or no yes Vector has a d how many directions for a vector a vector has Just One Direction okay so this is One Direction tensor so that so scalar is a tensor Vector is a tensor Matrix is a TENS okay so the vector has Just One Direction so I would call it One Direction tens okay for the Matrix for this one I has I have one this is One Direction and this is a second Direction so a matrix is two direction tensor okay look to the other side zero Direction tensor this is scaler One Direction tensor this is a vector two direction tensor this is a matrix three Direction tensor this is 3D we have X Y and Z three directions and so on you can have 4D and 5D and so on okay if I'm talking about stress the principal stresses how many directions for if we are talking about principal stresses how many directions principal stresses how many directions if I'm talking about principal principal stresses there is an over burden has a direction minimum horizontal stress has a direction maximum horal stress has a Direction so I have three directions for these three for these three stresses so at any point in Earth I will ask you what is the direction of overburden what is the direction of minimum horal stress what is the direction of Maxim stress and I would ask you about the values the magnitudes of each one right so stress in this case it is a tensor yes it is a tension okay but if I'm talking about overburden stress only and I'm asking you what how many directions for overburden stress how many directions for overb then stress just one if I'm asking you what is the direction of your body weight you will tell me because of gravity my body weight pointing to the center of Earth because it is One Direction so now you can call it One D tensor or you can call it Vector this is why I told you the minimum horizontal stress is a vector the maximum horizontal stress is a vector the overburden stress is a vector because each one of the three is one dimension tensil if you talk about all of them together and it have three directions still uh a tensil but when we talk we were talking last lecture or last two lectures I was not meaning the principal stresses in general I was talking about each one separate the overden is a vector the minimum has Just One Direction each one has Just One Direction but all of them together if you talking about stress in general now you have three different directions so you have a tensor you you presented by a tensor not a vector because a vector has Just One Direction I hope now you understand the difference between scalar vector and T so let me check if uh my is still here or okay yeah so this is my last slide two things this is to remind you about the principal stresses here is Sigma one this is the overburden here is Sigma H Max and here is Sigma hmen the sigma hmen in this case Sigma 3 this is the minimum horizontal stress and sigma H Max this is the maximum horizontal stress and sigma one in this case is the overb okay this is um normal faulting system okay so if if I want to describe the stresses in this point I need to use a tensor to represent stresses in this point but if I'm talking about each one separately it is just a vector can do that okay we already explained the the picture in uh the right side this is showing the hydraulic fracturing how it increase the contact area between the reservoir and the W board and how it bypass the formation damage and number three how it creates a very conductive Surface by using propen which keeps the fracture open after uh pumping and for these three reasons hyic fracturing improve productivity May I'm done so I'm not sure if you have more questions or we can uh conclude the session thank you thank you so much for effort and time for today it was really really so beneficial H thank you so much all for attending uh highlighting that this uh session is recorded and will be uploaded soon on P Petra YouTube channel so make sure to subscribe and our YouTube channel thank you all and bye thank you very much and have a wonderful rest of your day or enjoy your night thank you