This book mainly describes the theories and technologies for natural gas hydrate management in the deepwater gas well. There are 7 chapters in this book. Chapter 1 is an overview on hydrate risks in deepwater oil and gas development, which mainly introduces the hydrate formation and its hazards in deepwater oil and gas development; Chapter 2 is the formation and decomposition of natural gas hydrate, and the hydrate phase equilibrium model, the calculation method of hydrate formation and decomposition rates are given; Chapter 3 is the prediction for natural gas hydrate formation area in deepwater gas well, and puts forward related quantitative prediction method; Chapter 4 is the influence of hydrate phase transition on multi-phase flow in deepwater drilling well, which analyzes the change of multi-phase flow in the deepwater wellbore; Chapter 5 is the mechanism and prediction method for hydrate deposition and blockage in deepwater gas well, and establishes the related hydrate blockage model; Chapter 6 is the hydrate management technology in deepwater gas well, in which one new hydrate blockage management method based on HBFW is proposed. Chapter 7 is hydrate management software in deepwater gas well and case analysis, which analyzes the hydrate management schemes in deepwater gas well by case.

Contents1 Overview on Hydrate Risks in Deepwater Oil and Gas Development 11.1 Engineering Background of Hydrate Risks 11.2 Hydrate Risks During Deepwater Drilling and Well Control 21.3 Hydrate Risks During Deepwater Gas Well Test 41.4 Hydrate Risks During Deepwater Oil and Gas Production 41.5 Management Measures for Hydrate Risks 5References 62 Formation and Decomposition of Natural Gas Hydrate 92.1 Structure and Formation of NGH 92.2 Formation of NGH 132.2.1 Hydrate Phase Equilibrium Condition 132.2.2 Hydrate Formation Dynamics 192.2.3 Hydrate Formation in Gas Phase with Free Water and Its Rate 232.2.4 Hydrate Formation in Gas Phase Without Free Water and Its Rate 272.3 Decomposition of NGH 352.3.1 Hydrate Decomposition Above Freezing Point 362.3.2 Hydrate Decomposition Below Freezing Point 382.4 Formation and Decomposition of Hydrate Converted from Moving Bubbles 402.4.1 Mass Transfer Model of Moving Bubbles 402.4.2 Interphase Mass Transfer Rate 452.4.3 Formation and Decomposition of Hydrate Converted from Moving Bubbles 46References 473 Prediction for NGH Formation Area in Deepwater Gas Well 513.1 Coupling Between Hydrate Behavior and Multi-phaseFlow Characteristics 513.2 Prediction on Well/Pipeline Temperature and Pressure Fields in Annular-Mist Flow 533.2.1 Multiphase Flow Model 533.2.2 Model Solution 603.2.3 Model Validation 613.3 Prediction on Well/Pipeline Temperature and Pressure Field in Water-Saturated Gas Systems 653.3.1 Temperature Field Model 653.3.2 Pressure Field Model 673.4 Influencing Factors of NGH Phase Equilibrium in Well/Pipeline 673.4.1 Natural Gas Components 683.4.2 Natural Gas Density 683.4.3 Thermodynamic Inhibitor 693.4.4 Sand Content 703.5 Prediction and Influence Factors of Hydrate Formation Area in Deepwater Gas Well 733.5.1 Prediction Methods of Hydrate Formation Area Under Different Working Conditions 733.5.2 Influencing Factors of Hydrate Formation Area During Drilling 743.5.3 Influencing Factors of Hydrate Formation Area During Well Control 763.5.4 Influencing Factors of Hydrate Formation Area During Well Test 78References 824 Influence of Hydrate Phase Transition on Multiphase Flow in Deepwater Gas Well 854.1 Influence of Hydrate Phase Transition on the Rheology of Drilling Fluid 854.1.1 Experimental Device 864.1.2 Drilling Fluid Rheology Model Considering Hydrate Formation 874.1.3 Hydrate Formation Integration Constant of CHF 904.2 Influence of Hydrate Phase Transition on Multiphase Flow During Deepwater Drilling 964.2.1 Well Annulus Multiphase Flow Model During Deepwater Drilling 964.2.2 Influence of Hydrate Phase Transition on Bubble Migration 1014.2.3 Influence of Hydrate Phase Transition on Well Multiphase Flow Without Inhibitors 1034.2.4 Influence of Hydrate Phase Transition on Well Multiphase Flow with Inhibitors 107References 1085 Mechanism and Prediction for Hydrate Deposition and Blockage in Deepwater Gas Well 1115.1 Hydrate Particles Interactions 1115.1.1 Interaction Force Between Hydrate Particles 1145.1.2 Interaction Force of Hydrate Particle-Droplet-Hydrate Particle 1185.1.3 Interaction Force of Hydrate Particle-Droplet-Hydrate Particle Considering Liquid Bridge Solidification 1255.2 Hydrate Deposition and Blockage Model in Gas-Liquid-Solid Three-Phase Flow 1305.2.1 Initial Deposition Model of Hydrate Particle in Gas Core 1315.2.2 Influence of Liquid Film Atomization on Hydrate Particles Deposition 1325.2.3 Effective Deposition Coefficient of Hydrate Particle in Gas Core 1335.2.4 Hydrate Layer Growth and Hydrate Blockage 1355.2.5 Model Solution and Validation 1365.3 Hydrate Deposition and Blockage Model in Gas-Solid Two-Phase Flow 1435.3.1 Theory on Radial Migration of Solid Particles in Gas-Solid Two-Phase Flow 1445.3.2 Wells and Friedlander Model 1445.3.3 Hydrate Particles Deposition in Gas-Solid Two-Phase Flow 1475.3.4 Model Solution and Validation 1495.4 Hydrate Deposition and Blockage Model in Water-Saturated Gas Single-Phase Flow 1525.4.1 Hydrate Deposition and Blockage Model 1535.4.2 Model Solution and Validation 1545.5 Prediction for Hydrate Blockage During Deepwater Gas Well Control 1565.5.1 Basic Parameters in Case 1565.5.2 Prediction for Hydrate Formation Area 1585.5.3 Laws of Hydrate Deposition and Blockage 1585.5.4 Influence of Hydrate Deposition on Wellhead Back Pressure 1665.6 Prediction for Hydrate Blockage During Deepwater Gas Well Test 1675.6.1 Hydrate Blockage Free Window (HBFW) 1675.6.2 Model Solution Steps 1685.6.3 Quantitative Prediction for Hydrate Blockage 1695.6.4 Case Analysis for Predicting the Hydrate Blockage 171References 1776 Technologies for Hydrate Management in Deepwater Gas Well 1816.1 Classification of Chemical Inhibitors 1816.1.1 Thermodynamic Inhibitors 1816.1.2 Kinetic Inhibitors 1826.1.3 Anti-agglomerants 1836.2 Screening and Evaluation of Inhibitors 1836.2.1 Alcohol Inhibitors Screening 1836.2.2 Salts Inhibitors Screening 1856.2.3 Inhibitors Selection 1866.3 Parameters Design During Inhibitors Injection 1866.3.1 Injection System 1866.3.2 Injection Position 1876.3.3 Injection Pressure 1896.3.4 Injection Concentration 1896.3.5 Injection Rate 1896.3.6 Injection Amount 1916.4 Hydrate Blockage Management Method Based on Incomplete Inhibition 1936.4.1 Hydrate Blockage Management Based on the HBFW 1946.4.2 Hydrate Blockage Management Based on the Well Test System 1986.5 Risk Early-Warning of Hydrate Blockage 2006.5.1 Monitoring Device 2006.5.2 Early-Warning Flow 2016.5.3 Field Application 202References 2037 Hydrate Management Software in Deepwater Gas Well and Case Analysis 2057.1 Software Overview 2057.2 Software Composition 2067.2.1 Data Input Module 2067.2.2 Calculation Module of Well Temperature and Pressure Fields 2117.2.3 Calculation Module of Hydrate Phase Equilibrium Conditions 2117.2.4 Prediction Module of Hydrate Formation Area 2127.2.5 Optimization Module of Injection Parameters 2137.3 Case Analysis for Hydrate Management in Deepwater Gas Well 2157.3.1 Basic Parameters 2157.3.2 Prediction on Hydrate Formation Area 2167.3.3 Prediction on Hydrate Blockage 2287.3.4 Chart for Injection Concentration 2307.3.5 Chart for Injection Pressure 231References 232