Evaluation Geological Engineering Basics GEOL 4233 Class April 27, 2008 Dan Boyd Oklahoma Geological Survey Norman, Okla - PowerPoint PPT Presentation

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Evaluation Geological Engineering Basics GEOL 4233 Class April 27, 2008 Dan Boyd Oklahoma Geological Survey Norman, Okla PowerPoint Presentation
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Evaluation Geological Engineering Basics GEOL 4233 Class April 27, 2008 Dan Boyd Oklahoma Geological Survey Norman, Okla
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Evaluation Geological Engineering Basics GEOL 4233 Class April 27, 2008 Dan Boyd Oklahoma Geological Survey Norman, Okla

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  1. Evaluation Geological Engineering Basics GEOL 4233 Class April 27, 2008 Dan Boyd Oklahoma Geological Survey Norman, Oklahoma

  2. Geological Engineering Overview • Reservoir Issues • Porosity • Permeability • Fluid Saturation • Fluid / Pressure Terminology & Concepts • Fluid (Water, Oil Gas) • Pressure (Saturation, Mobility, Compressibility) • Drive Mechanisms • Oil • Gas • Multiphase Flow Issues (Coning) • Reservoir Management • General Principles • Production Curves • Improved Recovery

  3. General Reservoir Issues • Porosity • Permeability • Fluid Saturations

  4. Porosity • Storage Capacity • Nominal Pay Cutoffs • Oil: 10% • Gas: 8% • Porosity Types • Intergranular (clastics) • Intercrystaline (carbonates) • Fracture • Dissolution (moldic, vuggy, cavernous) • Logs • Density • Neutron • Sonic

  5. Booch Core Porosity vs. Depth

  6. Schematic Porosity vs. Depth Plot (Hard Rock Country) 15,000’ 20,000’ 5,000’ 10,000’

  7. Permeability • Producibility • Kv – Kh (vertical vs. horizontal) • Conventional Reservoirs • Fractured Reservoirs • Unconventional Reservoirs • Relative Permeability • Enhanced Permeability • Acid Treatment • Fracture Stimulation • Logs • Spontaneous Potential (SP) • Resistivity Suite

  8. Booch Core Porosity vs. Permeability (Maximum Values)

  9. Core Porosity vs. Permeability Plot

  10. Fluid Saturation • Water • Wetting (dewatering) • Connate • Irreducible (Swirr) • Oil • Water displacement (Soi) • Fractured Reservoirs • Unconventional Reservoirs • Gas • Molecular Size (mobility) • Water/Oil displacement (Sgi)

  11. Schematic Reservoir Grain Size vs. Water Saturation Grain Size (permeability) Shale (Magnified) Water Saturation Initial (complete pore volume) – Irreducible (rims only)

  12. Reservoir Sandstone Good Porosity = Lots of Space for Petroleum Pores (blue)

  13. Conventional vs. Non-Conventional Gas Accumulations

  14. Unconventional (Low-Perm) Shale (Organic-Rich) 1 Inch

  15. Pressures / Fluids

  16. Fluid Terminology Water: Connate Movable vs. Irreducible

  17. Schematic Reservoir Grain Size vs. Water Saturation Grain Size (permeability) Shale (Magnified) Water Saturation Initial (complete pore volume) – Irreducible (rims only)

  18. Fluid Terminology Water: Connate Movable vs. Irreducible Salinity (ppm): Chlorides vs. T.D.S. Fresh – Brackish – Normal Marine - Hypersaline Secondary Recovery (Waterflood) Compressibility (10x rule)

  19. Water Support Likely

  20. Water Support Unlikely

  21. Fluid Terminology Oil: Gravity (API) Viscosity (cp) GOR (gas to oil ratio) Saturated vs. Undersaturated (gas cap – secondary gas cap)

  22. Fluid Terminology Oil: Gravity (API) Viscosity (cp) GOR (gas to oil ratio) Saturated vs. Undersaturated (gas cap – secondary gas cap) Contrast with Condensate Live vs. Dead Sweet vs. Sour

  23. Fluid Terminology Gas: Heating Value Condensate Yield Condensate vs. Oil Wet vs. Dry Sweet vs. Sour Other Components (CO2, N2)

  24. Pressure Terminology ‘Normal’ Pressure (hydrostatic) Under-pressure (fluid leak-off) Over-pressure (incomplete de-watering) Measurements: Reservoir Pressure (BHP, calculated vs. measured) Flowing Tubing Pressure (FTP, at surface) Casing Pressure (between casing and tubing)

  25. Saturation Pressures Oil : Bubble Point Gas : Dew Point (retrograde – occurs in reservoir)

  26. Fluid Mobility / Compressibility • Molecular Size Mobility Compressibility • Gas - Small High Very High • Oil - Large Medium Moderate (~GOR) • Water - Medium Low Low (10x Rule)

  27. Drive Mechanisms

  28. Oil Reservoir • Drive Mechanisms • Solution Gas Drive (dissolved gas) (also called depletion) • Gas Expansion Drive (gas cap) • Water Drive • Combination Drive • Gravity Drainage

  29. Unconformity Trap

  30. Schematic Gravity Drainage Shallow (Low Pressure)

  31. Gas Reservoirs

  32. Gas Reservoir Drive Mechanism Dominantly Depletion Gas Gas / Water Contact

  33. Coalbed Methane Production