Advanced Reservoir Management and Engineering (eBook)

Front Cover 1
Advanced Reservoir Management and Engineering 4
Copyright Page 5
Contents 6
Preface 10
1 Well Testing Analysis 12
1.1 Primary Reservoir Characteristics 12
1.1.1 Types of Fluids 12
1.1.2 Flow Regimes 13
1.1.3 Reservoir Geometry 15
1.1.4 Number of Fluids Flowing in the Reservoir 17
1.2 Fluid Flow Equations 17
1.2.1 Darcy’s Law 17
1.2.2 Steady-state Flow 18
1.2.3 Unsteady-state Flow 33
1.2.4 Basic Transient Flow Equation 34
1.2.5 Radial flow of Slightly Compressibility Fluids 37
1.2.6 Radial Flow of Compressible Fluids 49
1.2.7 Pseudosteady State 55
1.2.8 Radial Flow of Slightly Compressible Fluids 59
1.2.9 Radial Flow of Compressible Fluids (Gases) 64
1.2.10 Skin Factor 65
1.2.11 Turbulent Flow Factor 68
1.2.12 Principle of Superposition 70
1.3 Transient Well Testing 75
1.3.1 Drawdown Test 77
1.3.2 Pressure Buildup Test 89
1.3.3 Horner Plot 90
1.3.4 Miller–Dyes–Hutchinson Method 97
1.3.5 MBH Method 100
1.3.6 Ramey–Cobb Method 105
1.3.7 Dietz Method 106
1.4 Type Curves 107
1.4.1 Gringarten Type Curve 112
1.5 Pressure Derivative Method 120
1.5.1 Model Identification 132
1.5.2 Analysis of Early-time Test Data 133
1.5.3 Analysis of Middle-time Test Data 135
1.5.4 Hydraulically Fractured Reservoirs 151
1.6 Interference and Pulse Tests 182
1.6.1 Interference Testing in Homogeneous Isotropic Reservoirs 184
1.6.2 Interference Testing in Homogeneous Anisotropic Reservoirs 189
1.6.3 Pulse Testing in Homogeneous Isotropic Reservoirs 194
1.6.4 Pulse Testing in Homogeneous Anisotropic Reservoirs 206
1.6.5 Pulse Test Design Procedure 206
1.7 Formation Testing 207
1.7.1 Supercharging 208
1.7.2 Flow Analysis 208
1.7.3 Example use of gradients 210
1.7.4 Solution 213
1.7.5 Fluid Identification 214
1.7.6 Advanced applications 215
1.8 Injection Well Testing 218
1.8.1 Injectivity Test Analysis 218
1.8.2 Pressure Falloff Test 222
1.8.3 Step-rate Test 231
1.9 Problems 232
2 Water Influx 238
2.1 Classification of Aquifers 238
2.1.1 Degree of Pressure Maintenance 238
2.1.2 Outer Boundary Conditions 239
2.1.3 Flow Regimes 239
2.1.4 Flow Geometries 240
2.2 Recognition of Natural Water Influx 240
2.3 Water Influx Models 241
2.3.1 The Pot Aquifer Model 241
2.3.2 The Schilthuis Steady-State Model 243
2.3.3 The Hurst Modified Steady-State Equation 245
2.3.4 The van Everdingen and Hurst Unsteady-State Model 247
2.3.5 The Carter and Tracy Water Influx Model 282
2.3.6 The Fetkovich Method 285
3 Unconventional Gas Reservoirs 292
3.1 Vertical Gas Well Performance 292
3.1.1 Gas Flow under Laminar (Viscous) Flowing Conditions 292
3.1.2 Gas Flow under Turbulent Flow Conditions 296
3.1.3 Back-Pressure Test 301
3.1.4 Future Inflow Performance Relationships 307
3.2 Horizontal Gas Well Performance 310
3.3 Material Balance Equation for Conventional and Unconventional Gas Reservoirs 312
3.3.1 The Volumetric Method 312
3.3.2 The Material Balance Method 314
3.3.3 Volumetric Gas Reservoirs 315
3.3.4 Water Drive Gas Reservoirs 320
3.4 Coalbed Methane 336
3.4.1 Gas Content 338
3.4.2 Density of the Coal 347
3.4.3 Deliverability and Drainage Efficiency 348
3.4.4 Permeability and Porosity 350
3.4.5 Material Balance Equation for Coalbed Methane 351
3.4.6 Prediction of CBM Reservoir Performance 357
3.4.7 Flow of Desorbed Gas in Cleats and Fractures 360
3.5 Tight Gas Reservoirs 361
3.5.1 Compartmental Reservoir Approach 363
3.5.2 Combined Decline Curve and Type Curve Analysis Approach 368
3.6 Gas Hydrates 417
3.6.1 Phase Diagrams for Hydrates 418
3.6.2 Hydrates in Subsurface 434
3.7 Shallow Gas Reservoirs 436
4 Performance of Oil Reservoirs 444
4.1 Primary Recovery Mechanisms 444
4.1.1 Rock and Liquid Expansion 444
4.1.2 Depletion Drive Mechanism 445
4.1.3 Gas Cap Drive 446
4.1.4 Water Drive Mechanism 449
4.1.5 Gravity Drainage Drive 451
4.1.6 Combination Drive Mechanism 453
4.2 The Material Balance Equation 454
4.3 Generalized MBE 455
4.3.1 Basic Assumptions in the MBE 455
4.3.2 Increasing Primary Recovery 460
4.3.3 Reservoir Driving Indices 462
4.4 The MBE as an Equation of a Straight Line 468
4.4.1 Case 1: Volumetric Undersaturated Oil Reservoirs 469
4.4.2 Case 2: Volumetric Saturated Oil Reservoirs 472
4.4.3 Case 3: Gas Cap Drive Reservoirs 480
4.4.4 Case 4: Water Drive Reservoirs 484
4.4.5 Case 5: Combination Drive Reservoirs 488
4.4.6 Case 6: Average Reservoir Pressure 489
4.5 Tracy's Form of the MBE 490
4.6 Problems 492
5 Predicting Oil Reservoir Performance 496
5.1 Phase 1. Reservoir Performance Prediction Methods 496
5.1.1 Instantaneous GOR 496
5.1.2 The Reservoir Saturation Equations and Their Adjustments 500
5.1.3 Undersaturated Oil Reservoirs 506
5.1.4 Saturated Oil Reservoirs 507
5.2 Phase 2. Oil Well Performance 519
5.2.1 Vertical Oil Well Performance 520
5.2.2 Horizontal Oil Well Performance 539
5.2.3 Horizontal Well Productivity under Steady-State Flow 542
5.2.4 Horizontal Well Productivity under Semisteady-State Flow 545
5.3 Phase 3. Relating Reservoir Performance to Time 546
5.4 Problems 548
6 Introduction to Enhanced Oil Recovery 552
6.1 Mechanisms of Enhanced Oil Recovery 552
6.2 Enhanced Oil Recovery Methods 554
6.3 Thermal Processes 555
6.3.1 Cyclic Steam Stimulation 555
6.3.2 Steam Flooding (Steam Drive) 557
6.3.3 Steam-Assisted Gravity Drainage 571
6.3.4 In Situ Combustion 573
6.4 Chemical Flood 577
6.4.1 Polymer Flood 578
6.4.2 Surfactant Slug and Micellar Solution Flood 585
6.4.3 ASP Flood 590
6.5 Miscible Gas Flood 591
6.5.1 Miscibility 592
7 Economic Analysis 598
7.1 Introduction 598
7.1.1 Tight Gas Optimal Spacing Example 599
7.1.2 Drill vs. Farmout Example 601
7.1.3 Value of Advanced Technology 601
7.2 Evaluation Criteria and Cash Flow Analysis 602
7.2.1 Payout 602
7.2.2 Number of Times Investment Returned 605
7.2.3 Discounting of Future Cash Flows, Time Value of Money 605
7.2.4 Period Discounting 608
7.3 Price Escalation and Constant Price Cases 608
7.3.1 SPEE Guidelines for Escalations 609
7.4 Present Value 609
7.4.1 SPEE-Recommended Evaluation Practice 611
7.4.2 Discounted Payout 611
7.4.3 Discounted Cash Flow Return on Investment 611
7.4.4 Net Present Value and Discounted Cash Flow Return on Investment 613
7.5 Rate Acceleration Investments 614
7.5.1 Present Value Ratio (PVR) 617
7.5.2 Growth Rate-of-Return (GRR) 618
7.5.3 Perpetuity 619
7.6 Weighted Average Cost of Capital 619
7.6.1 Conceptual Framework 619
7.6.2 Value of a Corporation 620
7.6.3 Market Value of Debt 620
7.6.4 Market Value of Equity 621
7.6.5 Value of the Firm 621
7.7 Risk Analysis 621
7.7.1 Adjusted Discount Rates 623
7.7.2 Sensitivity Analysis 623
7.7.3 Decision Trees and Utility Theory 624
7.7.4 Monte Carlo Simulations 626
7.8 Types of International Petroleum Fiscal Regimes 630
7.8.1 Background 630
7.8.2 Generic Contract Styles 630
7.8.3 Concessions 631
7.8.4 Joint Ventures 631
7.8.5 Tax/Royalty Schemes 632
7.8.6 Production Sharing Contracts 632
7.8.7 Ring Fencing 634
7.8.8 Reserve Treatment and Issues for PSCs 635
7.8.9 Service Contracts 635
7.8.10 Issues with PSC and Service Contracts 636
7.9 Country Examples 636
7.9.1 Brazil (Excluding Pre-Salt) 636
7.9.2 Indonesia 637
7.9.3 United Kingdom 638
7.9.4 Iraq Service Contracts 639
7.9.5 Summary 640
7.10 General Reserve Booking Issues 641
7.10.1 Petroleum Resources 641
7.10.2 Guidelines for Resource Estimation and Accounting 642
7.10.3 Resource Classification Framework 643
7.10.4 A Note on Risk and Uncertainty 644
7.10.5 Project-Based Resource Evaluations 645
7.10.6 Project Maturity Sub-Classes and Reserve Classes 645
7.10.7 Resource and Reserve Uncertainty 646
7.11 Historical SEC Reserve Regulations 647
7.11.1 Proved Area Definition (“Offsets”) 657
7.11.2 2009 SEC Changes 658
8 Financial Analysis 662
8.1 Fixed Capital Investments 662
8.1.1 Cost Basis 663
8.1.2 Cash Flow Consequences 663
8.1.3 Maintenance Expense 664
8.1.4 Additions of Fixed Capital 664
8.1.5 Working Capital 664
8.2 Financial Reporting 664
8.2.1 Generally Accepted Accounting Principles (GAAP) 664
8.2.2 Net Income 665
8.2.3 Timing Differences 665
8.2.4 Depreciation, Depletion, and Amortization (DD& A)
8.2.5 Deferred Tax 666
8.2.6 Cash Flow Generation 667
8.3 Mergers and Acquisitions 667
8.4 Overview of E& P Acquisition Environment
8.4.1 Tax Consequences 669
8.4.2 Accounting for Acquisitions 669
8.4.3 Pooling Accounting 670
8.4.4 Purchase Accounting 670
8.4.5 Due Diligence in Acquisitions 670
8.4.6 Valuation 671
9 Professionalism and Ethics 672
9.1 What Is a Profession? 672
9.2 Ethics 672
9.2.1 Guide for Professional Conduct 673
9.3 The Engineer as an Expert Witness 674
9.3.1 Credibility and Credentials 675
9.3.2 Compensation and Payments 676
9.3.3 The Expert Report 677
9.3.4 Depositions 678
9.3.5 Direct Examination 679
9.3.6 Cross-Examination 680
9.3.7 Intellectual Property 682
9.3.8 Junk Science 682
9.4 FCPA Considerations 683
9.5 Ethics Gone Awry, Ethical Dilemmas 684
9.5.1 The Case of the Unintended Consequences of Success Bonuses 684
9.5.2 How Much of Your Expertise Belongs to Your Employer? 686
9.5.3 Whose Witness Anyway? 687
9.5.4 Forced Rankings 688
9.5.5 Gifts and Entertainment 689
9.5.6 The Bribery Coast 690
References 694
Index 700