Learning Objectives Reservoir Rock Properties Core Sources and Seals Porosity and Permeability This section will cover the following learning objectives: Explain why petroleum fluids are found in underground reservoirs Describe the storage properties of rocks Describe the transport properties of rocks Describe the different kinds of rocks 1
Oil Factories Seal Structural Traps Reservoir Rock Sealing Rock Reservoir Source Anticline 2
Stratigraphic Traps Sealing Rock Reservoir Seal Reservoir Reservoir Rock Pinchout Source 3
Reservoir Rock Is Not All Solid Porosity Fluid-filled voids Phi ϕ 0 ϕ 1 4
Some Voids Are Connected Effective Porosity Some Voids Are Connected Total Porosity 5
Some Voids Are Connected Pore Connected Pores Allow Fluid Flow 6
Permeability 0 Pores Can Contain Multiple Fluids 7
Saturation Oil Saturation ;0 1 Water Saturation Gas Saturation Multiple Fluids Slow Things Down 1 ;0 1 ;0 1 8
Permeabilities Independent of Fluid Permeabilities Without Dimensions 9
Rocks Come in Three Flavors Rocks Igneous Rocks Come in Three Flavors Rocks Metamorphic Sedimentary These rocks are more likely to have porosity and permeability values large enough to accommodate commercial production Metamorphic Sedimentary Igneous 10
Sedimentary Rocks Can Be Mixtures Sandstone Rock fragments from other rocks 11
Limestone/Dolomite Remains of plants and animals Shale Dominated by clay minerals 12
Coal Dominated by carbon Summary Sources, Reservoir and Seal Porosity Effective Total Permeability Absolute Effective Relative Basic Lithology Types of Rock Sandstones, Limestones and Shale 13
Learning Objectives This section has covered the following learning objectives: Explain why petroleum fluids are found in underground reservoirs Describe the storage properties of rocks Describe the transport properties of rocks Describe the different kinds of rocks 14
Learning Objectives Reservoir Rock Properties Core Compressibility This section will cover the following learning objectives: Describe how rocks change shape under external stress Describe how rocks change shape under internal pressure Explain how stress and pressure affect rock permeability 15
Squeezing Rocks Compressibility Bulk compressibility 1 Bulk volume Change in pressure 16
Uniaxial Compressibility Hydrostatic Compressibility 17
Shrinkage versus Expansion Poisson s Ratio Shrinkage Expansion 18
Uniaxial Compressibility Hydrostatic versus Uniaxial Compressibility Pore Volume Compressibility x 10-6, 1/psi [x 10-4, 1/MPa] [43.5] [36.3] [29.0] [21.8] [14.5] [7.2] Compressibility vs Net Confining Stress (CMS-300) [6.9] [13.8] [20.7] [27.6] [34.5] [41.4] Net Confining Stress, psi [MPa] 19
Overburden Overburden Overburden 20
Uniaxial Compression Uniaxial versus Hydrostatic Compression?? 21
Uniaxial versus Hydrostatic Compression?? Lateral Confining Pressures?? 22
Porosity Homogeneous, isotropic material Porosity 23
Pore Compressibility Fluid Pressure 24
Pore Compressibility Pore Volume Compressibility Pore volume compressibility 1 Pore volume Change in pore pressure 25
Bulk Volume Compressibility Bulk compressibility Pressure versus Stress 1 Bulk volume Change in overburden pressure 26
Bulk versus Pore Volume Compressibility Pressure versus Stress 1 1 27
Net Confining Stress Effective stress Effect on Permeability External stress Biot s constant Pore pressure 28
Summary Bulk Volume Compressibility Uniaxial Hydrostatic Poisson s ratio Pore Volume Compressibility Net Effective Stress Effect on Permeability Learning Objectives This section has covered the following learning objectives: Describe how rocks change shape under external stress Describe how rocks change shape under internal pressure Explain how stress and pressure affect rock permeability 29
Learning Objectives Reservoir Rock Properties Core Heterogeneity and Anisotropy This section will cover the following learning objectives: Define the terms "heterogeneity" and "anisotropy" Describe how porosity and permeability are upscaled Describe how rock texture affects porosity and permeability Explain the differences between various definitions of reservoir thickness 30
Heterogeneity Upscaling Porosity #1 Porosity #2 Porosity #3 31
Homogeneity Porosity #1 Averaging Porosity #2 Porosity #3 ϕ 1 h 1 ϕ 1 h 2 ϕ 1 h 3 32
Upscaling Upscaling Permeability ϕ average h total k average h total 33
Parallel Flow Perpendicular Flow 34
Anisotropy Random Flow k h???? k v.. 35
Rock Texture Texture 36
Grain Size Distribution Cementing 37
Rocks Come in Layers Cap Rock Reservoir Thickness 38
Top and Base Top and Base Cap Rock Reservoir Top Reservoir Reservoir Base Cap Rock Reservoir Gross thickness 39
Gross vs. Net Net = Gross on this side Net < Gross on this side Pay vs. Net Pay Reservoir Reservoir Pay Reservoir Reservoir Non- Reservoir Non- Reservoir Not Pay Oil-Water Contact Also Not Pay 40
Dip 45 True Stratigraphic Thickness 41
Observed Well Thickness Well Deviation 42
True Vertical Thickness Summary Heterogeneity Weighted Averages Upscaling Anisotropy Texture Gross vs. Net vs. Pay True Vertical vs. True Stratigraphic Dip Deviation 43
Learning Objectives This section has covered the following learning objectives: Define the terms "heterogeneity" and "anisotropy" Describe how porosity and permeability are upscaled Describe how rock texture affects porosity and permeability Explain the differences between various definitions of reservoir thickness 44
Learning Objectives Reservoir Rock Properties Core Maps and Geostatistics This section will cover the following learning objective: Describe several techniques for interpolating rock property data between wells 45
Geostatistics Basic Geostatistics Well #1 Well #2 Reservoir 46
Nearest Neighbor Step Changes Property Value 47
Linear Interpolation Property Value Inverse Distance Property Value ϕ 1 ϕ 2 ϕ a d 1 d 2 1 1 1 1 48
Multiple Dimensions Variable Exponent Porosity Value ϕ 1 ϕ 2 1 1 1 1 1 1 1 1 1 1 Well Cross Section Interpolated values with n = 1 Interpolation of properties between wells Well #1 Well #2 49
Variable Exponent 1 1 1 1 Porosity Value ϕ 1 ϕ 2 Generalization Well Cross Section Interpolated values with n = 2 Well #1 Well #2 1 1 1 1 Interpolation of properties between wells 50
Kriging [ ] Data Holes D, ft [m] 51
Data Transforms Permeability - Millidarcies III Crystal Size > 0.06 mm [0.002 in.] II/III Crystal Size 0.02-0.05 mm [0.0008-0.002 in.] II Crystal Size < 0.02 mm [0.0008 in.] Correlations: log Permeability - Millidarcies III Crystal Size > 0.06 mm [0.002 in.] II/III Crystal Size 0.02-0.05 mm [0.0008-0.002 in.] II Crystal Size < 0.02 mm [0.0008 in.] Porosity [%] Porosity [%] 52
Classification Co-Kriging 53
Digital Maps Earth Models 54
Manual Maps 2100 ft [640 m] Contouring 55
Contour Maps 2100 ft [640 m] Step 1: Post the Wells North East 56
Step 2: Post the Values 15 12 40 0 35 47 Decide on Intervals 45 Next you need to decide which values you are going to contour Conventionally, we choose equally spaced values over a range that will cover all the values at the wells shown on the map 32 0 10 20 30 40 38 0 57
Step 3: Start at the Top 15 12 40 0 35 47 Step 4: Next Contour 12 45 32 38 0 15 38 47 45 40 35 32 0 0 58
Step 5: Third Contour 15 12 40 0 35 47 Step 6: Fourth Contour 12 45 32 38 0 15 38 47 45 40 35 32 0 0 59
Step 7: Last Contour 15 12 40 0 35 47 45 Step 8: Dressing Contours 12 32 38 0 15 38 47 45 40 35 32 0 0 60
Step 8: Smoothing Algorithms 15 12 40 Summary 0 35 47 Basic Geostatistics Nearest Neighbor Inverse Distance Kriging Data Transforms Co-Kriging 45 32 Contouring 38 0 61
Learning Objectives This section has covered the following learning objective: Describe several techniques for interpolating rock property data between wells 62
Learning Objectives Reservoir Rock Properties Core Log and Core Analysis This section will cover the following learning objectives: Describe how log analysis is used to calculate reservoir engineering rock properties Describe how core analysis is used to measure reservoir engineering rock properties 63
Log Analysis Related PetroAcademy Skill Modules Petrophysical Data and Open Hole Logging Operations Core Mud Logging, Coring and Cased Hole Logging Operations Core Gamma Ray and Spontaneous Potential Logging Core Porosity Logging (Density, Neutron and Sonic) Core Formation Testing Core Resistivity Logging Tools and Interpretation Core Petrophysical Evaluation Core Core Analysis Core Knowledge Special Petrophysical Tools: NMR and Image Logs Core 64
Running Logs on Wireline Displaying Log Data Graphically 65
Spontaneous Potential Log Spontaneous Potential Depth Spontaneous Potential Log Shale Shale Depth Spontaneous Potential Wet Sand Oil Sand 66
Resistivity Log Resistivity Depth Resistivity Log Shale Depth Resistivity Wet Sand Oil Sand Shale 67
Spontaneous Potential Log and Resistivity Log Spontaneous Potential Resistivity Shale Wet Sand Depth Shale Oil Sand Shale Displaying Log Data Graphically Depth 68
Calculating Properties from Log Data R o Archie s Law Equation R t 69
Archie s Law Assumptions S w = water saturation in lower sand [vol/vol] R o = resistivity in lower sand if S w =1 [Ohm-m] [Ohm-ft] R t = actual resisitivity in lower sand [Ohm-m] [Ohm-ft] Humble Formula 0.62. R o = resistivity in lower sand if S w =1 [Ohm-m] [Ohm-ft] R w = in-situ water resistivity [Ohm-m] [Ohm-ft] ϕ = porosity [vol/vol] 70
Density Log Response 1 ρ b = density log reading [g/cc] [lb/in. 3 ] ρ ma = rock grain density [g/cc] [lb/in. 3 ] ρ fl = in-situ fluid density [g/cc] [lb/in. 3 ] ϕ = porosity [vol/vol] Fluid Density 1 ρ oil = in-situ oil density [g/cc] [lb/in. 3 ] ρ water = in-situ water density [g/cc] [lb/in. 3 ] S w = water saturation in lower sand [vol/vol] 71
Simultaneous Solution Archie s Law Humble Formula 0.62. Density Log Response Fluid Density 1 1 Measured Data Data We Want To Know Auxiliary Data Cased Hole Logs 72
Logging While Drilling (LWD) Core Analysis 73
Measurement Scale 6 in. [152 mm] Before or After 1-1.5 in. [25-38 mm] Wireline Percussion Sidewall Coring Threaded Joint Hard-Formation Coring Bullet Soft-Formation Coring Bullet 6 in. [152 mm] Coring Bit Up to 2 ft [0.6 m] Explosive Coring Bullet After Firing 74
Dean-Stark Retort 75
Outside Dimensions 4 mm [0.16 in.] Inside Dimensions 100 psi [0.7 MPa] 76
Calculating Porosities and Saturations ϕ ϕ porosity [ ] sample bulk volume [cm 3 ] [in. 3 ] sample grain volume [cm 3 ] [in. 3 ] sample water volume [cm 3 ] [in. 3 ] sample water saturation [ ] Permeameters 77
Klinkenberg Effects Calculating Permeabilities q = test fluid injection rate [cc/sec] k = observed permeability [D] A = core cross sectional area [cm 2 ] [in. 2 ] perpendicular to flow direction x = core length [cm] [in.] parallel to flow direction p = pressure drop [atm] along core length μ = test fluid viscosity [cp] 78
Summary Basic Log Analysis Qualitative Interpretation Quantitative Interpretation Basic Core Analysis Preparing the Core Measuring Porosity Measuring Permeability Learning Objectives This section has covered the following learning objectives: Describe how log analysis is used to calculate reservoir engineering rock properties Describe how core analysis is used to measure reservoir engineering rock properties 79
This is Reservoir Engineering Core Reservoir Rock Properties Core Reservoir Rock Properties Fundamentals Reservoir Fluid Core Reservoir Fluid Fundamentals Reservoir Flow Properties Core Reservoir Flow Properties Fundamentals Reservoir Fluid Displacement Core Reservoir Fluid Displacement Fundamentals PetroAcademy TM Applied Reservoir Engineering Skill Modules Properties Analysis Management Reservoir Material Balance Core Reservoir Material Balance Fundamentals Decline Curve Analysis and Empirical Approaches Core Decline Curve Analysis and Empirical Approaches Fundamentals Pressure Transient Analysis Core Rate Transient Analysis Core Enhanced Oil Recovery Core Enhanced Oil Recovery Fundamentals Reservoir Simulation Core Reserves and Resources Core Reservoir Surveillance Core Reservoir Surveillance Fundamentals Reservoir Management Core Reservoir Management Fundamentals 80