1. Evaluation Geological Engineering Basics GEOL 4233 Class Dan Boyd Oklahoma Geological Survey Fall 2011 Semester

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

6. Booch Core Porosity vs. Depth

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

8. 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

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

13. Core Porosity vs. Permeability Plot

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

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

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

17. Conventional vs. Non-Conventional Gas Accumulations

19. 1 Inch Shale (Organic-Rich) Unconventional (Low-Perm)

21. Pressures / Fluids

22. Fluid Terminology Water: Connate Movable vs. Irreducible

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

24. 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)

25. Water Support Likely

26. Water Support Unlikely

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

28. 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

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

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

31. c

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

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

37. Drive Mechanisms

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

42. Unconformity Trap

44. Schematic Gravity Drainage Shallow (Low Pressure)

45. Gas Reservoirs

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

48. Coalbed Methane Production

51. Coalbed Methane Well (Oklahoma)

52. Gas Oil Water American Petroleum Institute, 1986 Multi-Phase Flow Issues

53. “ D 6 “ HORIZONTAL WELLBORE TRAJECTORIES LOWER D6 ( S 36 ) STRUCTURE NET SAND S.L. -7150 B-94 B-181 B-46 B-98 B-92 01000 M.200400600800 B-54 B-99 0 10 20 30 40 20 10 0 40 30 20 B-56 0 -7200 40 30 B-69 B - 184 LATERAL N B - 185 LATERAL 10 50 B-176 -7100 -7150 S.L.

54. BADAK - 185 HORIZONTAL SCHEMATIC WELLBORE STRATIGRAPHY ( VERTICAL EXAGGERATION = 20X ) -7090’ PILOT HOLE 78008000 8400 8600880090009200 MEASURED DEPTH TVD SS -7100’ -7110’ -7120’ -7130’ -7140’ -7150’ INITIAL TARGET DEPTH B-184 PILOT GOC ~ OIL RIM UPPER LIMIT IN PILOT BEGIN O/W TRANSITION ZONE IN PILOT 50 % Sw IN PILOT 8200 S 36 S 33

55. (Elan Plus Interpretation) Badak-185 Horizontal Lateral

56. Pressure Gradients

58. Reservoir Management Preservation of Reservoir Energy (pressure) Water into the bottom Gas into the top Long term gain for short term pain (production restraint)

59. General Principles

60. Production Primary Secondary (Waterflood) Tertiary (Enhanced)

61. Strong City Field Gas Production

62. Vertical Arbuckle Gas Well Cum: 44.5 BCF

63. Vertical Coalbed Methane Well (Cherokee Platform)

64. Vertical Hartshorne Coalbed Methane Well

65. Horizontal Hartshorne Coalbed Methane Well

66. Vertical Woodford Gas Well

67. Horizontal Woodford Gas Well

69. Remedial work ?

70. Misener Oil Well Cum: 670 MBO + 207 MMCF Current Rate: 24 BOPD Approximately 240 MMCF Vented

71. Primary Recovery

72. Improving Recovery Secondary (Waterflood) Enhanced (Tertiary)

73. Secondary Recovery WaterGasSteamChemicalFire Pumped into the reservoir to force additional petroleum out of the pores in the reservoir rock InjectionWells Producing Wells Of 60% Remaining in Reservoir

75. Tecumseh NW Field Example of Ideal Primary – Secondary Production Curve

76. Shawnee Lake SE Field Secondary 2/3rds of total production

77. Enhanced Recovery

80. Postle Field Oil Production

81. Next: Volumetrics (Bring a calculator and straight edge to class)