Oil Well Testing Handbook

CHAPTER 1 Introduction 1.1 Role of Oil Well Tests and Information in Petroleum Industry1.2 History of Oil Well Testing1.3 Uses of Oil Well Tests1.4 Oil Well Data Acquisition, Analysis and Management Efficient Oil Well Test Analysis Programs1.5 Selecting Oil Wells for Optimum Stimulation Treatment1.6 Reservoir System Characterization Process Most Common Oil Well Test Interpretation Methods 1.7 Scopes and Objective1.8 Orginization 1.9 Units Systems and Conversions References for Additional Reading CHAPTER 2Fundamentals of Reservoir Oil Flow Analysis 2.1 Introduction 2.2 Basic Fluid Flow Equations in Oil Reservoir Steady-State Flow Equations and Their Practical Applications Ideal Steady-State Flow Equations - Radial Flow Pseudo-Steady-State Flow Equations Flow Equations for Different Flow Regimes Time to Reach Pseudo-Steady State Unsteady-State (Transient) Flow Equations Radial Diffusivity Equation Various Dimensional Flow Geometry 2.3 Dimensionless Form of Flow Equations, Groups and Variables 2.4 Analytical Solutions of Fluid Flow Equations Bounded (Finite) Cylindrical Reservoir Infinite-Acting Reservoir With Line Source Well Pseudo-Steady State Flow Wellbore Storage Effects and Solutions Flow Analysis in Generalized Reservoir Geometry Wellbore Damage Analysis and Stimulation Time and Radius of Investigation Equations 2.5 Application of Superposition Techniques Effects of More Than One Well Rate Change Effects Pressure Change Effects Simulation Boundary Effects Use of Horner's Approximation 2.6 Numerical Models and Their Applications Purpose and Objective of Reservoir Simulation Reservoir Model Development Process Selection of Numerical Simulation Models and Applications 2.7 Formulation and Numerical Solutions of Reservoir Simulation Equations Single Phase Flow Three Phase Oil-Gas-Water Flow Two-Phase Oil-Gas Flow in Fractured Reservoir 2.8 Steady State and Semi-Steady State Pressure Distribution Calculations 2.9 Pressure Distribution Calculations Unsteady-State Conditions Infinite External Boundary Conditions Finite External Boundary Conditions 2.10 Unsteady-State Pressure Distribution Calculations in Directional Well 2.11 Summary References for Additional Readings CHAPTER 3Transient Well Testing Methods For Horizontal Oil Wells 3.1 Introduction 3.2 Flow Equations for Horizontal Oil Wells Steady State Flow Equations and Solutions Unsteady State Equations and Solutions Calculating Effective Wellbore Radius for Horizontal Oil Well Effect of Formation Damage on Horizontal Well Productivity Investigating Effect of Sv and b on Horizontal Well Productivity Ratio Pseudo-Steady State Equations and Solutions Shape Related Skin Factor for Vertical and Fractured Oil Wells Shape Factors for Horizontal Oil Wells Calculation of Skin Factor for Horizontal Oil Wells Pseudo-Steady State Productivity Calculation Methods 3.3 Horizontal Oil Well Performance During Transient State 3.4 Transient Well Testing Techniques in Horizontal Oil Wells Early Time Radial Flow Equation Intermediate Time Linear Flow Equation Late Time Radial Flow Equation Late Time Linear Flow Equation Possible Flow Regimes and Analytical Solutions 3.5 Flow Time Equations and Solutions 3.6 Pressure Response Equations and Methods of Analysis Under Condition of Pressure Drawdown Test Under Condition of Pressure Buildup Test 3.7 Horizontal Well Pressure and Normalized Pressure Derivative 3.8 Effects of Wellbore Storage 3.9 Summary References for Additional Reading CHAPTER 4Pressure Drawdown Testing Techniques For Oil Wells 4.1 Introduction 4.2 Pressure Time History for Constant Rate Drawdown Test 4.3 Transient Analysis - Infinite Acting Reservoirs 4.4 Late Transient Analysis - Bounded (Developed) Reservoirs 4.5 Semi-Steady State Analysis - Reservoir Limit Test 4.6 Two-Rate Flow Test Analysis When Initial Pressure is Not Known When Initial Pressure is Known 4.7 Variable Rate Flow Tests Modified Variable Rate Case Transient Case Average Reservoir Pressure Calculations Semi-Steady State Case 4.8 Multi-Rate Flow Test Analysis Multi-Rate, Single Phase Test Multi Rate, Multi-Phase Test 4.9 Drawdown Rate Normalization Equations and Solutions Analysis Methods, Their Applications and Limitations Drawdown Rate Normalization Equations and Solutions 4.10 Summary References for AdditionalReading CHAPTER 5Pressure Buildup Analysis Techniques For Oil Wells 5.1 Introduction 5.2 Ideal Pressure Buildup Test 5.3 Actual Buildup Test - Infinite Reservoir 5.4 Pressure Buildup Test Analysis - Infinite Acting Reservoir Effects and Duration of After-Flow Test Calculating Flow Capacity and Formation Permeability Estimating Skin Factor Pressure Drop Due to Skin Determining Effective Wellbore Radius Flow Efficiency and Damage Ratio Estimating Skin Effects of Incompletely Perforated Interval Determining Skin Effects in a Partially Completed Damaged Well Estimating Reservoir Size from Two Pressure Buildup Tests Typical Shapes of Buildup Curves 5.5 Pressure Buildup Testing Methods for Finite (Bounded) Reservoir Horner and MBH Method Miller-Dyes-Hutchinson (MDH) Method Extended Muskat Method Slider's Technique for Analyzing Buildup Test 5.6 Multiphase Buildup Test Analysis 5.7 Afterflow Analysis Using Russell's Techniques 5.8 Pressure Buildup Tests Proceeded by Two Different Flow Rates 5.9 Variable Rate Pressure Buildup Analysis 5.10 Multiphase Multirate Buildup Test Analysis5.11 Rate Normalization Techniques and Procedures - Pressure Buildup Data Analysis Methods, Their Uses and Limitations Buildup Rate Normalization Equations and Solutions Normalized Pressure Modified MDH Plot Analysis Normalized Pressure Squarer Root Time plot Average Reservoir Pressure Equation 5.12 Summary References for AdditionaReadingCHAPTER 6Original and Average Reservoir Pressure Estimation Methods 6.1 Introduction 6.2 Original Reservoir Pressure in Infinite Reservoirs 6.3 Estimating Average and Initial Pressure Horner and MBH Method MDH Method Dietz Method Ramey and Cobb Methods Modified Muskat Method Arps and Smith Method 6.4 Estimating Constant Pressure at Aquifer in Water Drive Reservoirs Boundary and Average Pressure Estimating Methods 6.5 Summary References for Additional Reading CHAPTER 7Well Testing Methods for Naturally Fractured Oil Reservoirs 7.1 Introduction7.2 Identification of Natural Fractures 7.3 Characteristics of Naturally Fractured Reservoirs 7.4 Typical Pressure Drawdown Behavior Curve Shapes 7.5 Pressure Buildup Behavior Characteristics 7.6 Well Test Interpretation Methods, Uses and Limitations Pseudo Steady-State Model Transient State Model Pressure Gradient Models Type Curve Matching Technique Pressure Derivative Method 7.7 Buildup Analysis Techniques For Tight Reservoir Matrix 7.8 Interpretation of Interference Tests in Matrix and Fractured Reservoirs Uses of Interference Tests Dimensionless Fracture Pressure Solution Dimensionless Matrix Pressure Solution Interference Test Analysis Using Type Curve Match Equations 7.9 Horizontal Well Pressure Behavior Curve Shapes Identification of Various Flow Periods Well Test Analysis Equations and Solutions 7.9 Horizontal Well Production Forecasting for Dual Porosity Reservoir 7.10 Summary References for Additional Reading CHAPTER 8Fundamentals of Type Curve Matching Methods For Oil Wells 8.1 Introduction 8.2 Application to Conventional Tests Ramey's Type Curves Earlougher and Kersch Type Curves McKinley's Type Curves 8.3 Fracture Type Curve Matching Techniques Type Curves - Vertical Fractured Oil Wells 8.4 Types Curves - Horizontal Fractured Oil Wells Using Pressure Drawdown Data Estimation of Upper Limit of Permeability Thickness Product 8.5 Summary References for Additional ReadingCHAPTER 9Flow Regime Identification and Analysis Using Special Methods 9.1 Introduction 9.2 Fracture Linear Flow Period 9.3 Bilinear Flow 9.4 Formation Linear Flow 9.5 Pseudo-Radial Flow9.6 Type Curve Matching Methods - Field Case Studies Case 1 - Bilinear Flow Type of Analysis Case 2 - Pressure Data Partially Match Curve for the Pseudo-Radial Flow Period Case 3 - Pressure Exhibit a Half Slope Line on a Log-Log Plot Case 4 - Pressure Data Partially Falling in the Pseudo-Radial Flow Period 9.7 Summary References for Additional Reading CHAPTER 10Applications of Pressure Derivative in Oil Well Test Analysis 10.1 Introduction 10.2 Determining Pressure Derivative Functions 10.3 Log-Log Pressure and Pressure Derivative Diagnostic Plots 10.4 Pressure Derivative Trends For Other Common Flow Regimes 10.5 Pressure Derivative Applications to Well Test Analysis 10.6 Pressure derivative Analysis Methods Pressure Buildup Test Data Matching Procedure Pressure Drawdown Test Data Matching Procedures 10.7 Fractured Reservoir Systems Pseudo-State Interporosity Flow Transient Interporosity Flow 10.8 Summary References for Additional Reading CHAPTER 11Massive Hydraulic Fractured Oil Well Behavior Analysis 11.1 Introduction11.2 Methods of Evaluating MHF Fractured Oil Wells 11.3 Analyzing Infinite Flow Capacity Fractures 11.4 Analyzing Finite Flow Capacity Fractures Constant Wellbore Pressure Case Constant Rate Case 11.5 Estimating Formation Characteristics - Finite Conductivity Vertical Fractures Curve Matching Procedures Conventional Method of Analysis 11.6 Pretreatment Testing of Hydraulically Fractured Candidate Horner Analysis Linear Flow Analysis - High Conductivity Fractures Type Curve Analysis Bilinear Flow Analysis - Low Conductivity Fractures11.7 Summary References for Additional Reading CHAPTER 12Drill-Stem Testing Methods 12.1 Introduction 12.2 DST Equipment and Operational Procedures Basics of DST Operations DST Pressure Behavior 12.3 Recommended Flow and Shut-in Time for Drill-Stem Tests12.4 Trouble Shooting DST Pressure Charts 444 DST Charts for Barrier Detection 12.5 Checking Validity and Consistency of Reported DST Data12.6 Estimating Average Flow Rate 12.7 DST Analysis Methods, Uses and Their Limitations Horner's Plot Method Type Curve Matching Methods Correa and Ramey's Method Drill-Stem Buildup Test Analysis With Limited Data 12.8 Wireline Formation Test Data Evaluation Open-Hole Formation Test Closed-Hole Formation Test Empirical Interpretation Charts for Formation Tester Results Reservoir Rock's Porosity Distribution System Analysis Matrix Pore Volume Calculation Fracture Pore Volume Calculation Partitioning Coefficient Estimation Well Skin Effects 12.9 Summary References for Additional Reading CHAPTER 13Oil Well Potential Evaluation and IPR Relationships 13.1 Introduction 13.2 Classification and Identifying Values of Permeability-Thickness Product 13.3 Isochronal and Flow After-Flow Tests 13.4 Wellbore Restriction Analysis Procedure and Method of Analysis Well Test Effect of Changing Completion Zone on Well IPR 13.5 Factors Affecting IPR Curves 13.6 Criteria for Identifying Type of Drives 13.7 Classifications to Predict IPR Curves13.8 Basic Assumptions to Predict IPR Curves 13.9 Well Inflow Performance Calculation Methods for Vertical Oil Wells From Limited Information Single Phase Liquid and Two Phase Flow When Flow Efficiency Not Equal to One Two Phase Flow Producing Water 13.10 Inflow Performance (IPR) Relationship Solution Gas Drive - Vertical and Horizontal Oil Wells 13.11 Development Procedure for Preparation of Future IPR Curves IPR Calculating for Future Conditions 13.12 Summary References for Additional Reading CHAPTER 14Interference and Pulse Testing and Analysis Methods 14.1 Introduction 14.2 Interference Test Analysis Techniques Interference Test Analysis by Type Curve Matching 14.3 Analysis of Pulse Test Pressure Response Characteristics of Pressure ResponsePulse Test Responses With Flow and Shut-in Time Pulse Test Analysis Methods Horizontal Pulse Test Analysis 14.4 Vertical Pulse Test Design and Analysis Methods Vertical Pulse Test Design Calculations 14.5 Design and Analysis of Unequal Pulses Pulse Test Designing Methods Pulse Test Analysis Methods 14.6 Summary References for Additional Reading CHAPTER 15Injection Well Transient Testing and Analysis 15.1 Introduction 15.2 Injectivity Test Analysis Methods Under Steady State Conditions Waterflood Reservoir With M.R =1 Liquid Filled Unit-Mobility-Ratio Reservoirs 15.3 Pressure Fall-off Test Analysis Methods Liquid Filled Unit-Mobility-Ratio Reservoirs Prior to Reservoir Fillup (Unit Mobility Ratio) Prior to Reservoir Fillup (Non Unit Mobility Ratio)15.4 Two Rate Injection Test Analysis 15.5 Step Rate Injectivity Testing Techniques Estimation of Formation Fracture Pressure 15.6 Summary References for Additional Reading CHAPTER 16Well Testing Methods in Multilayered Oil Reservoir Systems 16.1 Introduction 16.2 Identification of Layered Oil Reservoir Systems 16.3 Analyzing Pressure Behavior Multilayered Systems Layered Reservoir With Crossflow Layered Reservoir Without Crossflow Composite Reservoirs Interlayer Crossflow Reservoirs 16.4 Concept of Reservoir Layer Fracture Conductivity 16.5 Pressure-Production Performance Response Equations Constant Producing Pressure Constant Producing Rate 16.6 Investigating Degree of Communication and Type of Crossflow 16.7 Pressure Buildup Response Characteristics in Layered Reservoir Systems 16.8 Pressure Analysis Methods for Oil Wells Producing Commingled Zones Conventional Analysis Method (Horner Plot) MDH Method Extended Muskat Plot Other Methods 16.9 Factors Effecting Multilayered Reservoir Performance 16.10 Economic Aspects of Interlayer Crossflow 595 References for additional reading CHAPTER 17Pressure Analysis Methods in Heterogeneous Oil Reservoir Systems 17.1 Introduction 17.2 Effect of Pressure on Rock Properties17.3 Major Causes of Heterogeneities 17.4 Pressure Responses Near No Flow Boundaries Methods of Estimating Distance to a Linear Discontinuity 17.5 Effect of Hydraulic Diffusivity on Reservoir Behavior 17.6 Simple Procedures and Guidelines to Determine Reservoir Heterogeneity Properties 17.7 Simple Approach to Estimate Fracture Trends or Heterogeneities 17.8 Determination of Reservoir Parameters and Fracture Orientation 17.9 Defining Reservoir Heterogeneity By Multiple Well Testing Techniques Homogeneous Isotropic Reservoir Systems Anisotropic Reservoir Systems Heterogeneous Reservoir Systems 17.10 Method for Calculating Fracture Orientation 17.11 Estimating Two Dimensional Permeability With Vertical Interference Testing17.12 Application of Pulse Tests to Describe Reservoir Heterogeneity Homogeneous Isotropic Reservoir Systems Anisitropic Reservoir Systems 17.13 Validity of Various Models and Steps to Obtain Reservoir Descriptions 17.14 Summary References for Additional ReadingCHAPTER 18Oil Well Testing - Field Case Studies 18.1 Introduction 18.2 Oil Well Test Evaluation Sheet 18.3 Method to Convert Bottom Hole Pressure at Instrument Depth To Reservoir Datum 18.4 Determining Average Depth of Oil Reservoirs 18.5 Stimulation Efforts Evaluation, Summary and Results Low Pressure Reservoirs -Multiphase Pressure Buildup Test Analysis Field Case Studies 18.6 Transient Pressure Drawdown Test Analysis General Equations Method of Analysis Field Case Studies 18.7 Skin Effect, Skin Factor, and Flow Efficiency Positive (+) and Negative (-) Skins Skin Factor Equations and Their Relationships Causes of Positive and Negative Skins Relationships With Flow Efficiency 18.8 Factors Responsible For Reduction in Formation Permeability 18.9 Improvement Analysis As a Result of Fracture Treatment References for Additional Reading CHAPTER 19Decline Curve Analysis Methods19.1 Introduction 19.2 Transient Decline Behavior Analysis Transient Drainage Radius During Infinite-Acting Period Characteristics of Exponent b During Transient Period Production Characteristics During Transient Period Constant Pressure Rate Decline Constant Rate Production, Pressure Declining 19.3 Pseudo-Steady State Decline Forecasting Rate Decline19.4 Characteristics and Classification of Production Decline Curves Hyperbolic Decline Behavior Exponential Decline Behavior Harmonic Decline Behavior Characteristics and Decline Exponent b Estimating Techniques Harmonic Decline Curve 19.5 Decline Response Behavior in Fractured Reservoirs Classifications and Limitations of Log Log Type Curves Type Curve Matching Methods 19.6 Summary References for Additional ReadingCHAPTER 20Overall Skin Effects and Impact On Oil Well Performance 20.1 Introduction20.2 Concept of Skin Factor 20.3 Wellbore Damage Effects 20.4 Effective Wellbore Radius Concepts and Productivity Index Calculation Techniques Vertical Wells Horizontal Wells 20.5 Skin Factor Due to Partial Penetration20.6 Skin Factor Due to Perforation20.7 Skin from Partial Completion and Slant20.8 Skin Factor Due to Reduced Crushed Zone Permeability 20.9 Slant Well Damage Skin Effect on Well Productivity 20.10 Horizontal Well Damage Skin Effects Impact of Skin Effect on Horizontal Oil Well Performance 20.21 Summary References for Additional Reading APPENDIX A Conversion Factors Between Unit Systems APPENDIX B Correlation Tables and Charts for Dimensionless Functions References for Additional Readings APPENDIX C Pressure Drop Through Vertical, Inclined and Horizontal Oil Wells C.1 Hagedorn and Brown Method - Vertical Oil Wells C.2 Beggs and Brill Method - Inclined and Horizontal Pipes References for Additional Readings APPENDIX D Oil and Water PVT Properties and Correlation Equations D.1 Oil PVT Properties and Correlations Bubble Point (Saturation) Pressure Factors Affecting Saturation Pressure Correlations For Saturation Pressure Calculation D.2 Solution Gas Oil Ratio D.3 Oil Formation Volume Factor (FVF) Correlations to Determine Oil FVF D.4 Total Formation Volume Fcator D.5 Oil Density D.6 Oil Viscosity Factors Affecting Oil Viscosity Methods to Estimate Oil Viscosity D.7 Oil Compressibility D.8 Reservoir Rock Properties D.9 Reservoir PVT Water Properties Use of New Tables to Determine Formation Water PVT Properties References for Additional Readings APPENDIX E Substantial Set of Problems Without Solution E.1 Routine exercises to Practical Applications Nomenclature 7Bibliography Subject Index