Metallurgy and Corrosion Control in Oil and Gas Production

Robert Heidersbach, PhD, is the President of Dr. Rust, Inc., a consulting firm that specializes in corrosion, metallurgy, and materials consulting for a variety of international clients, including oil and gas production, military hardware, construction, litigation, and failure analysis. He was previously a faculty member in ocean engineering at the University of Rhode Island, chemical engineering at Oklahoma State, and metallurgy and materials engineering at California Polytechnic State University.

Preface xiii 1 Introduction to Oilfi eld Metallurgy and Corrosion Control 1 Costs, 1 Safety, 2 Environmental Damage, 2 Corrosion Control, 3 2 Chemistry of Corrosion 4 Electrochemistry of Corrosion, 4 Electrochemical Reactions, 4 Electrolyte Conductivity, 5 Faraday's Law of Electrolysis, 5 Electrode Potentials and Current, 5 Corrosion Rate Expressions, 8 pH, 10 Passivity, 10 Potential-pH (Pourbaix) Diagrams, 11 3 Corrosive Environments 13 External Environments, 13 Atmospheric Corrosion, 14 Water as a Corrosive Environment, 15 Soils as Corrosive Environments, 16 Corrosion under Insulation, 17 Internal Environments, 18 Crude Oil, 19 Natural Gas, 19 Oxygen, 19 CO2, 20 H2S, 22 Organic Acids, 27 Scale, 27 Microbially Infl uenced Corrosion (MIC), 28 Mercury, 31 Hydrates, 31 Fluid Flow Effects on Corrosion, 33 4 Materials 36 Metallurgy Fundamentals, 36 Crystal Structure, 36 Strengthening Methods, 37 Mechanical Properties, 38 Fracture, 42 Creep, 45 Thermal Expansion, 45 Forming Methods, 45 Wrought versus Cast Structures, 45 Welding, 46 Materials Specifi cations, 49 API, 49 AISI-The American Iron and Steel Institute, 49 ASTM International-formerly the American Society for Testing and Materials, 49 ASME, 49 SAE International, 49 UNS, 50 NACE-The Corrosion Society, 50 Other Organizations, 50 Use of Materials Specifi cations, 50 Carbon Steels, Cast Irons, and Low-Alloy Steels, 51 Classifi cations of Carbon Steel, 52 Strengthening Methods for Carbon Steels, 53 Heat Treatment of Carbon Steels, 53 Quenched and Tempered (Q&T) Steels, 54 Carbon Equivalents and Weldability, 54 Hard Spots, 55 Cleanliness of Steel, 55 Cast Irons, 55 CRAs, 55 Iron-Nickel Alloys, 56 Stainless Steels, 56 Nickel-Based Alloys, 60 Cobalt-Based Alloys, 61 Titanium Alloys, 62 Copper Alloys, 63 Aluminum Alloys, 66 Additional Considerations with CRAs, 68 Polymers, Elastomers, and Composites, 70 5 Forms of Corrosion 75 Introduction, 75 General Corrosion, 75 Galvanic Corrosion, 77 Galvanic Coupling of Two or More Metals, 77 Area Ratio, 78 Polarity Reversal, 83 Conductivity of the Electrolyte, 83 Control of Galvanic Corrosion, 83 Pitting Corrosion, 84 Occluded Cell Corrosion, 84 Pitting Corrosion Geometry and Stress Concentration, 85 Pitting Initiation, 85 Pitting Resistance Equivalent Numbers (PRENs), 86 Statistics, 86 Prevention of Pitting Corrosion, 86 Crevice Corrosion, 87 Alloy Selection, 88 Filiform Corrosion, 88 Intergranular Corrosion, 89 Stainless Steels, 89 Corrosion Parallel to Forming Directions, 90 Aluminum, 90 Other Alloys, 91 Dealloying, 91 Mechanism, 91 Selective Phase Attack, 91 Susceptible Alloys, 92 Control, 92 Erosion Corrosion, 92 Mechanism, 92 Velocity Effects, 93 Materials, 95 Cavitation, 95 Areas of Concern, 95 Control, 98 Environmentally Induced Cracking, 98 SCC, 99 HE and H2 S-Related Cracking, 101 Hydrogen Attack, 105 Liquid Metal Embrittlement (LME), 105 Corrosion Fatigue, 106 Other Forms of Corrosion Important to Oilfi eld Operations, 107 Oxygen Attack, 107 Sweet Corrosion, 107 Sour Corrosion, 108 Mesa Corrosion, 108 Top-of-the-Line (TOL) Corrosion, 108 Wire Line Corrosion, 109 Additional Forms of Corrosion Found in Oil and Gas Operations, 109 Additional Comments, 113 6 Corrosion Control 117 Protective Coatings, 117 Paint Components, 117 Coating Systems, 118 Corrosion Protection by Paint Films, 118 Desirable Properties of Protective Coating Systems, 119 Developments in Coatings Technology, 120 Useful Publications, 120 Surface Preparation, 120 Purposes of Various Coatings, 123 Generic Binder Classifi cations, 124 Coatings Suitable for Various Service Environments or Applications, 126 Coatings Inspection, 126 Areas of Concern and Inspection Concentration, 131 Linings, Wraps, Greases, and Waxes, 133 Coatings Failures, 137 Metallic Coatings, 143 Water Treatment and Corrosion Inhibition, 146 Oil Production Techniques, 147 Water Analysis, 148 Gas Stripping and Vacuum Deaeration, 148 Corrosion Inhibitors, 148 Cathodic Protection, 154 How Cathodic Protection Works, 155 Types of Cathodic Protection, 157 Cathodic Protection Criteria, 168 Inspection and Monitoring, 170 Cathodic Protection Design Procedures, 174 Additional Topics Related to Cathodic Protection, 177 Summary of Cathodic Protection, 180 Standards for Cathodic Protection, 180 7 Inspection, Monitoring, and Testing 186 Inspection, 187 Visual Inspection (VI), 187 Penetrant Testing (PT), 188 Magnetic Particle Inspection (MT), 188 Ultrasonic Inspection (UT), 189 Radiography (RT), 190 Eddy Current, 191 Positive Material Identifi cation (PMI), 192 Thermography, 192 Additional Remarks about Inspection, 193 Monitoring, 193 Monitoring Probes, 193 Mass-Loss Coupons and Probes, 194 Electrical Resistance (ER) Probes, 197 Electrochemical Corrosion Rate Monitoring Techniques, 197 Hydrogen Probes, 200 Sand Monitoring, 201 Fluid Analysis, 201 Bacterial Growth Monitoring, 203 Additional Comments on Monitoring, 204 Testing, 204 Hydrostatic Testing, 204 Laboratory and Field Trial Testing, 204 8 Oilfield Equipment 209 Drilling and Exploration, 209 Wireline, 212 Coiled Tubing, 212 Wells and Wellhead Equipment, 213 History of Production, 214 Downhole Corrosive Environments, 214 Tubing, Casing, and Capillary Tubing, 220 Inhibitors for Tubing and Casing in Production Wells, 223 Internally Coated Tubing for Oilfi eld Wells, 226 Material and Corrosion Concerns with Artifi cial Lift Systems, 228 Wellheads, Christmas Trees, and Related Equipment, 231 Facilities and Surface Equipment, 233 Piping, 233 Storage Tanks, 236 Heat Exchangers, 238 Other Equipment, 241 Bolting and Fasteners, 241 Flares, 249 Corrosion under Insulation, 249 Pipelines and Flowlines, 249 Pipeline Problems and Failures, 252 Forms of Corrosion Important in Pipelines and Flowlines, 253 Repairs and Derating Due to Corrosion, 254 Casings for Road and Railway Crossings, 255 Pipeline Materials, 256 Hydrotesting, 257 External Corrosion, 257 Internal Corrosion, 260 Inspection and Condition Assessment, 262 References, 265 Index 270