2. 2
1 Petroleum Geology 8
Source Rocks 9
Reservoirs 10
Porosity 10
Permeability 10
Reservoir Drive Mechanism 11
Solution Gas Drive 11
Gas Cap Drive 11
Aquifer (Water) Drive 12
Water And Gas Injection 12
Gravity Drainage 12
Gas & Gas Condensate Reservoirs 12
Origin of Hydrocarbons 13
Inorganic Origin (Abiogenic Origin) 13
Organic Origin 13
Hydrocarbon Maturation 16
Hydrocarbon Migration 17
2 Petrophysical Characteristics of Rocks 18
Volume of Shale 19
Clay Mineralogy 20
Cation Exchange Capacity 22
Porosity 23
Siliciclastic rocks 23
Carbonate rocks 23
Simple cubic packing 24
Hexagonal packing 24
Rhombohedral packing 24
Secondary Porosity 24
Permeability 26
Matrix Mineral Constituents 27
Resistivity 29
Saturation 30
Archie's models 30
The Waxman-Smits model 32
Movable Oil 32
Reserves And Estimated Ultimate Recovery (EUR) 33
Estimated Ultimate Recovery (EUR) 34
3 Open Hole Logging 35
Types Of Boreholes 36
Types Of Well logs 36
History Of Well Logs 36
3. 3
Electric Logs And How They Are Acquired 38
Uses Of Well Logs 39
Open hole 39
Cased Hole 39
Environmental Effects And Corrections 39
Subsurface Temperatures 42
Temperature Gradient 44
Temperature Gradient Calculation 44
Formation Temperature Calculation 44
Bore Hole Environment 45
Lithostatic Pressure (Overburden) 45
Hydrostatic Pressure 45
Invasion 46
4 Caliper Log 48
Caliper Tool 49
Log Presentation 49
Caliper Interpretation 51
Factors Influencing Caliper Responses 52
Uses Of The Caliper Log 52
5 SP Log 53
Electrolytes 54
Theory Of Spontaneous Potential 54
Streaming Potential 54
Electrochemical Potential 54
SP Mechanism 55
Static Spontaneous Potential (SSP) 55
Environmental Effects 55
Bed Thickness 55
Borehole and Invasion 56
Shale Content 56
Hydrocarbon Content 56
SP As A Sand/Shale Discriminator 56
SP Rw Epilogue 57
SP Log as Shale Volume Indicator 58
6 GR Log 59
Sources of Gamma Radiation 60
GR Response in different Rock types 60
Uses Of gamma Ray log 60
The Gamma Ray Log As A Sand/Shale Discriminator 61
Gamma Ray Log As A Shale Volume Indicator 61
Borehole Environment Corrections 63
Spectral Gamma Ray Log 64
Uses of Spectral Gamma ray 64
Shale Volume Calculations From Spectral Gamma Ray 64
4. 4
7 Density Log 66
Theoretical Basis 67
Density Log As A Porosity Tool 68
Lithology Determination - PEF, Or Z Logs 70
Hydrocarbon Effect 71
Clay Minerals effect 71
Heavy Minerals Effect 71
8 Neutron Log 72
Theoretical Basis 73
Neutron Log as a Porosity Indicator 74
Neutron Porosity as a lithology Indicator 75
Pulsed Neutron Capture Logs (PNC) 75
Theory of Operation 75
Capture Cross Section (SIGMA) 76
Applications 79
Log-Inject-Log Measurements For Residual Oil Saturation 79
Pulsed Neutron Spectroscopy Logs (PNS) 79
Chlorine Log As A Porosity Indicator 81
Carbon Oxygen Log As A Lithology Indicator (C/O) 81
Elemental Capture Spectroscopy Log (ECS) 84
Reservoir Saturation Log 84
Time Lapse logs 86
9 Sonic Logs 87
Theoretical Basis 89
Unconsolidated Formations & Wyllie Formula 91
Raymer-Hunt-Gardner Equation 92
Sonic As A Porosity Tool 93
Hydrocarbon Effect 94
Clay Minerals Effect 94
Sonic as a cement integrity indicator 94
Characteristics of Good Cement 95
Gas Effect 95
Bond Index 95
Factors affecting Bond Index 95
CBL log 96
Good Cement 96
No Cement 96
Partial Cement 97
Microannulus (Micro Gap Between Cement And Casing) 97
Cement Without Bond To Formation 98
Cement Bond In Hard Formations 98
Typical Log Readings 99
PRO’s & CON’s 100
10 Dipole Sonic Log 101
5. 5
VP – VS Relation 102
Lithology 102
Compressional Wave Velocity (Vp) &Sheer Wave Velocity (Vs) 103
Calculation of Compressional bulk modulus of porous rock (Kc) 103
Calculation of Poisson's Ratio(Ѵ) 104
Calculation of Bulk modulus (Kb) 105
Calculation of Bulk Compressibility (Cb) 105
Calculation of Biot's Constant 105
Calculation of Young's Modulus (E) 105
Calculation of Brittleness Coefficient (Cbrit) 106
Calculation of Modulus of compressibility (Kc) 106
Elastic Constants 107
11 Nuclear Magnetic Resonance Measurements 108
Theoretical Basis 109
T1 Relaxation 109
T2 Relaxation 110
Pore Size And Fluid Moveability 111
Free Fluid Index 113
NMR As A Porosity Tool 113
BVI Determination 114
SBVI (Spectral) Model 117
NMR Permeability 118
Free-Fluid (Coates) Model 118
Mean-T2 Or Schlumberger-Doll-Research (SDR) model 119
Direct Hydrocarbon Typing 119
Time-Domain Analysis (TDA) 119
Diffusion Analysis 120
Nmr Applications In Carbonates 120
12 Resistivity Measurements 122
Formation Water Saturation (Sw) 123
Electrode tools 124
Normal 124
Unfocused Devices 124
Laterologs 125
Unfocused Devices 125
Focused Devices 125
Spherically Focused devices 126
Dual Laterologs 126
Laterolog Corrections 128
Induction Logs 129
Dual Induction Logs 130
Other Induction Devices 130
Flushed Zone Resistivity Logs 131
Microlog 131
6. 6
Other Microresistivity Logs 132
Formation Water Resistivity Measurement 133
Resistivity As A Dipmeter Tool 134
Resistivity As A Porosity Tool 134
13 Dielectric (DPT) Logs And Electromagnetic Propagation (EPT) Logs 136
Theoretical Basis 137
DPT & EPT Logs As A Porosity Tool 138
Complex Refractive Index Method (CRIM) 138
Propagation Time Method (Tpo) 138
Water Saturation Calculation In Uninvaded Zones 140
EPT Log As A Shale Volume Indicator 141
DPT As Water – Hydrocarbon Discriminator 141
14 Borehole Imaging 142
Electrical Borehole Images 143
Static images 143
Dynamic images 143
Acoustic Borehole Images 144
Downhole Video Images 144
Uses Of Borehole Images 145
Fracture And Fault Occurrence And Orientation 145
Fracture Aperture 146
Borehole Breakouts, In Situ Stress Interpretation 146
Stratigraphic Interpretation 146
Sedimentologic Interpretation 147
15 Log Response In High Angle And Horizontal Wells 148
High Angel – Horizontal well Characteristics 149
Measurement Response 151
Resistivity 151
Density 152
Neutron 152
Other Measurements 153
Geosteering 153
Deep Reading Devices For Geosteering 153
16 Interpretation Techniques 155
Formation Water Resistivity (Rw) 156
Rwa Concept 156
True Resistivity Values From Log Data (Corrections) 156
Induction Tool 157
Laterolog 157
Traditional Correction Method 159
Modern Correction Method (Inversion for invasion parameters) 159
Archie Water Saturations: Sw And Sxo 161
Clean formations 162
Resistivity Vs. Porosity Crossplots 163
7. 7
Rwa comparison 164
Resistivity-Ratio Methods 164
Flushed-zone method 164
Invaded-Zone Method 165
Shaly Sand Formations 167
Laminated Sand/Shale Model 167
Bulk Volume Water (Dual Water) 169
Quick-Look Interpretation Methods 170
Rxo/Rt Quicklook 170
Visual quick look Scaling (Lithology & Porosity) 171
Quick-Look Lithology 172
Gamma ray logs 172
Spontaneous Potential (SP) Logs 174
Formation Density Logs (Alone) 174
Photoelectric Absorption (Pe) Logs 175
17 Multiple Log Interpretation Techniques 176
Neutron-Density Lithology and Porosity Plot 177
Neutron-Sonic Lithology Plot 178
Density-Sonic Lithology Plot 179
M-N Lithology Plot 179
18 Cross Plot Interpretation Techniques 181
Hingle Crossplot 182
Flushed Zone Resistivity-Porosity Crossplots 184
Pickett Crossplot 185
Porosity Water Saturation Crossplot (Buckle’s) 187
19 Case Sudies 189
Case study 1 : Clean Gas Bearing Sand 190
Case study 2 : Carbonate Reservoir 196
Case Study 3 : Shaly Sand 201
Provided Excel sheets
1 Calculation of Rwe, RW, SSP from SP Log 5. Matrix density - Nlith Sheet and Plot
2 GR Correction and Vsh calculation 6. Mlith - Nlith calculation and plot
3. Density Porosity Quick look Interpretation 7. Complete analysis sheet for Clean Formation
4. Sonic Porosity Quick look interpretation 8. Complete analysis sheet for Shaly Sand Fm
