Fundamentals of Corrosion and Scaling: A Handbook for Petroleum and Environmental Engineers Book

Acknowledgments xiii Preface xv Foreword xvii
1 Introduction to Corrosion 1
1.1 Introduction 1
1.2 Definition of Corrosion 2
1.3 Introduction to Electrochemistry 2
1.4 Corrosion Agents in Drilling and Producing Operations 4
1.5 Requirements for Electrochemical Corrosion 5
1.5.1 Components of Electrochemical Corrosion 10
1.6 Chemistry of Corrosion and Electromotive Force Series 11
1.6.1 Actual Electrode Potentials 12
1.7 Galvanic Series 13
1.7.1 Cathode/Anode Areal Ratio 14
1.7.2 Polarization 14
1.8 Corrosion of Steel 16
1.9 Gaseous Corrodants 17
1.9.1 Oxygen 18
1.9.2 Hydrogen Sulfide 19
1.9.3 Carbon Dioxide 23
1.9.4 Alkalinity of Environment 24
1.10 Cathodic Protection 27
1.11 Role of Bacteria in Corrosion 27
1.12 Corrosion in Gas-Condensate Wells 28
1.13 Corrosion Rate Measurement Units 31
2 Types of Corrosion 35
2.1 Introduction 35
2.2 Sweet Corrosion 36
2.3 Sour Corrosion 37
2.4 Classes of Corrosion 38
2.4.1 Stress-Induced Corrosion 41
2.5 Types of Cracking in Drilling and Producing Environments 42
2.5.1 Hydrogen Embrittlement (Sulfide Cracking) 42
2.5.2 Hydrogen Blistering 43
2.5.3 Corrosion Fatigue 43
3 Microbial Corrosion 49
3.1 Introduction 49
3.1.1 Microbial Growth and Metabolism 52
3.2 Microbes Associated with Oilfield Corrosion 57
3.3 Microbial Interaction with Produced Oil 59
3.4 Microorganisms in Corrosion 59
3.4.1 Prokaryotes 60
3.4.2 Eukaryotes 62
3.5 Different Mechanisms of Microbial Corrosion 62
3.6 Corrosion Inhibition by Bacteria 64
3.7 Microbial Corrosion Control 64
4 Corrosion Control and Detection 71
4.1 Introduction to CorrosionControl 71
4.2 Cathodic Protection 71
4.3 Conditions for the Steady State or Limiting Corrosion Rate 75
4.3.1 Dangerous Inhibitors 79
4.4 Inhibitors and Passivators 79
4.4.1 Classification of Inhibitors 81
4.5 Coating 84
4.6 Detection of Corrosion 86
4.6.1 Chemical Tests 86
4.6.2 Microbial Tests 86
4.6.3 Electrochemical Tests 87
4.6.4 Pipeline Tests 87
4.7 Measurement of Corrosion 88
4.7.1 Visual Inspection 88
4.7.2 Caliper Surveys 88
4.7.3 Casing Thickness Logs 89
4.7.4 Radiography 89
4.8 Nondestructive Test Methods 89
4.8.1 Metal Loss Rate Tests Using Coupons 90
4.8.2 Other Corrosion Rate Monitors 90
5 Casing and Pipeline Corrosion 93
5.1 Introduction 93
5.2 Types of Casing 93
5.2.1 Cassion Pipe 94
5.2.2 Conductor Pipe 94
5.2.3 Surface Casing 96
5.2.4 Intermediate Casing 96
5.2.5 Production Casing 97
5.2.6 Liners 97
5.3 Corrosion of Steel 99
5.3.1 External Casing Corrosion 99
5.3.2 Casing Corrosion Inspection Tools 100
5.4 Protection of Casing from Corrosion 102
5.4.1 Wellhead Insulation 103
5.4.2 Cementation 103
5.4.3 Completion Fluids 104
5.4.4 Steel Grades 105
5.4.5 Casing Leaks 106
5.4.6 Cathodic Protection of Casing 106
5.5 Interaction of Old with New Pipeline 113
6 Scaling 117
6.1 Hardness and Alkalinity 117
6.2 Mineral Scales 118
6.2.1 Calcium Carbonate Scale 118
6.2.2 Sulfate Scales 123
6.3 Prediction of Scale Formation 123
6.4 Solubilities of Various Sulfates and Carbonates 131
6.5 Solubility of Calcite, Dolomite, and Magnesite and Mixture of These Carbonates 131
6.6 Relative Permeability Concepts 132
6.6.1 Effect of Water Hardness on Relative Permeability Curves 135
6.6.2 Effect of Water Chemistry on Oil Recovery 137
6.7 Scale Inhibition 137
7 Water Quality Control 141
7.1 Introduction 141
7.2 Injection Suitability 142
7.2.1 Clay Swelling 142
7.2.2 Formation and Deposition of Insoluble Material in the Formation 144
7.2.3 Increase in Oil Saturation 145
7.2.4 Suspended Solids 146
7.2.5 Movement of Formation Fines 147
7.2.6 Sources of Suspended Solids 148
7.3 Corrosion 150
7.3.1 Some Causes of Waterflood Corrosion 152
7.3.2 Carbon Dioxide 152
7.3.3 Hydrogen Sulfide 152
7.3.4 Oxygen 153
7.3.5 Interactions of the Gases 154
7.3.6 Bacterial Corrosion (See Chapter 3) 155
7.4 Use of Seawater for Injection Purposes 155
7.4.1 Characteristics of Seawater 156
7.4.2 Dissolved Oxygen 157
7.4.3 Calcium Carbonate Saturation 157
7.4.4 pH of Seawater 157
7.4.5 High Sulfate Ion Content 158
7.4.6 Magnesium Ion 158
7.4.7 Marine Life 158
7.4.8 Seasonal Changes in Composition of Seawater 159
7.4.9 Oil Content 159
7.5 Selection of Water Intake Location 159
7.5.1 Shallow Well in Seawater Aquifer 160
7.5.2 Intake from Nearshore Area 160
7.5.3 Offshore Intake 161
7.6 Design of Water Intake 161
7.6.1 Trash Screen 161
7.6.2 Fine Screen 161
7.6.3 Chlorination 162
7.6.4 Filtration 162
7.6.5 Deaeration of Seawater 163
7.6.6 Oxygen Scavenging 163
7.6.7 Stabilization of Seawater 164
7.6.8 Temperature of Seawater 164
7.6.9 Biocidal Treatment of Seawater 165
7.6.10 Corrosion Inhibition 165
7.7 Test Methods Used in Waterflooding Operations 166
7.7.1 Dissolved Oxygen 166
7.7.2 pH Change 167
7.7.3 The Membrane Filter Test 168
7.7.4 Total Iron Count Increase 169
7.7.5 Sulfate-Reducing Bacteria 169
7.7.6 Total Bacteria 170
7.7.7 Corrosion Coupons 171
7.7.8 Significance of Various Tests 173
7.7.9 Reporting of Test Data 183
7.8 COPRA Correlation 183
7.9 Preparation of Water for Subsurface Injection 184
7.9.1 Oil Removal 185
7.9.2 Gravity Separation 186
7.9.3 Flotation 188
7.9.4 Removal of Solids (Filtration) 189
7.9.5 Slow Sand Filters 190
7.9.6 Rapid Sand Filters 190
7.9.7 High-Rate Rapid Sand Filters 191
7.9.8 Diatomaceous Earth Filters 194
7.9.9 Selection of Diatomite 194
7.10 Removal of Dissolved Gases 196
7.11 Equipment Considerations 196
7.11.1 Pipelines 196
7.11.2 Separators 197
7.11.3 Volume and Origin of Suspended Material to Be Removed 198
7.11.4 Aggressiveness of Waters 199
7.11.5 Value of Space on Which Facilities Are to Be Located 199
7.11.6 Filtration Equipment 199
7.11.7 Clarification 200
7.11.8 In-line Flocculation Systems 200
7.11.9 Filter-aid Filters and In-line Flocculation Filters 201
7.12 Degassing Equipment 202
7.12.1 Deaeration Equipment 202
7.13 Chemical Mixing and Feed Equipment 202
8 Economics of Corrosion 209
8.1 Introduction 209
8.2 Direct and Indirect Cost of Corrosion 210
8.3 Major Industrial Categories of Corrosion Costs 211
8.3.1 Infrastructure 212
8.3.2 Utilities 213
8.3.3 Production and Manufacturing 214
8.4 Corrosion-Control Economics and Preventive Methods 217
8.5 Galvanic Versus Imposed Direct Electrical Current in Cathodic Protection 219 A Sample Problems and Questions 223 A.1 Sample Problems and Questions (Solutions and Answers are Provided) 223 A.2 Sample Questions and Problems (No Solutions) 233 B Glossary 237 C Conversion of Units 257 C.1 Temperature Conversion Formulas 264 C.2 Approximate Equivalents 264 C.3 Theoretical Aspects 265 Index 269