Reservoir Modeling Webinar

Introduction

• Presenter: Manchester Hustavi, Reservoir Geologist at Illinois State Geological Survey
• Topic: Concepts and fundamentals of reservoir modeling

Key Concepts

Responsibilities of a Reservoir Geologist

• Familiarity with multiple subjects:
  • Sedimentology
  • Interpretation of depositional environments
  • Seismic interpretation
  • Petrophysical data (e.g., water saturation, porosity, permeability)
  • Collaboration with reservoir engineers

Importance of 3D Modeling

• Historical use of 2D models
• Advantages of 3D models:
  • Better visualization of spatial relationships
  • Ability to model complex structures and faults

Seismic Interpretation

• Geophysicists provide horizons from seismic interpretations
• Integration of seismic data with well data
• Use of depositional environment interpretations as trends

Data Integration

• Collaboration with various experts (geophysicists, petrophysicists, reservoir engineers)
• Iterative process of model adjustment based on findings

Types of Depositional Environments

• Carbonate vs. Siliciclastic reservoirs
• Various environments and their impact on porosity and permeability:
  • Turbidites
  • Fluvial and deltaic environments
  • Channel systems

Zonation

• Importance of creating a framework for reservoirs
• Lithostratigraphy vs. Sequence Stratigraphy:
  • Sequence Stratigraphy provides more accurate zonation based on time surfaces

Diagenesis

• Key processes affecting reservoirs:
  • Dissolution
  • Compaction
  • Cementation
  • Dolomitization

Reservoir Modeling Workflow

Structural Maps

• Importing wellheads, surveys, formation tops, and structural maps
• Creation of Isochore and Isopach maps based on well data

Grid Construction

• Creation of discrete cells (geocellular model)
• Stratigraphic and structural frameworks:
  • Horizons from seismic data
  • Fault surfaces

Property Modeling

• Distribution of properties (e.g., porosity, permeability) across the grid
• Use of geostatistical algorithms for interpolation/extrapolation

Geostatistics

• Analysis of similarity and dissimilarity in data
• Creation of variograms to model properties between wells
• Comparison of deterministic vs. stochastic methods:
  • Deterministic methods can overestimate/underestimate properties
  • Stochastic methods provide multiple realizations for better accuracy

Calculation of Reservoir Volumes

• Parameters needed:
  • Area of the reservoir
  • Thickness
  • Porosity
  • Water saturation
  • Formation volume factor

Questions and Answers

Common Questions

• Methods for upscaling permeability: Arithmetic for porosity, geometric for horizontal permeability, harmonic for vertical permeability
• Data requirements for static and dynamic modeling: Wellheads, surveys, log data, seismic horizons, faults
• Use of stochastic models in reservoir simulation: Provides multiple realizations to inform decisions
• Importing geo-bodies: Used in facies modeling to create trends for property modeling

Final Remarks

• Importance of collaboration with various experts to create accurate models
• Learning multiple subjects and software tools is essential for reservoir geologists

Conclusion

• Reminder of upcoming courses and feedback forms for attendees