Preface to second edition .................................... xiii
Preface to first edition ....................................... xv
Acknowledgements ............................................. xvii
Chapter one Introduction ........................................ 1
1.1 Natural gas ................................................ 2
1.1.1 Sales gas ........................................... 2
1.1.2 Hydrates ............................................ 3
1.2 The water molecule ......................................... 3
1.2.1 The normal boiling point of water ................... 3
1.2.2 Enthalpy of vaporization ............................ 5
1.2.3 Expansion upon freezing ............................. 6
1.3 Hydrates ................................................... 9
1.4 Water and natural gas ..................................... 11
1.4.1 Free-water .......................................... 11
1.5 Heavy water ............................................... 12
1.6 Additional reading ........................................ 13
1.7 Units ..................................................... 13
Bibliography ................................................... 14
References ..................................................... 14
Appendix 1A. A Periodic Table of the Elements .................. 15
Chapter two. Hydrate types and formers ......................... 17
2.1 Type I hydrates ........................................... 17
2.1.1 Type I formers ..................................... 18
2.2 Type II hydrates .......................................... 19
2.2.1 Type II formers .................................... 20
2.3 Type H hydrates ........................................... 20
2.3.1 Type H formers ..................................... 20
2.4 The size of the guest molecule ............................ 20
2.5 n-Butane .................................................. 22
2.6 Other hydrocarbons ........................................ 22
2.7 Cyclopropane .............................................. 22
2.8 2-Butene .................................................. 23
2.9 Hydrogen and helium ....................................... 23
2.9.1 Update ............................................. 23
2.10 Chemical properties of potential guests ................... 24
2.11 Liquid hydrate formers .................................... 24
2.12 Hydrate forming conditions ................................ 24
2.12.1 Pressure-Temperature ............................... 24
2.12.2 Composition ........................................ 25
2.12.3 Caution ............................................ 27
2.12.4 Nitrogen ........................................... 28
2.12.5 Ethylene ........................................... 28
2.12.6 Propylene .......................................... 29
2.13 V+LA + H Correlations ..................................... 30
2.13.1 Ethylene ........................................... 31
2.14 LA + LH + H Correlations .................................. 35
2.15 Quadruple points .......................................... 36
2.15.1 Cyclopropane ....................................... 37
2.16 Other hydrate formers ..................................... 37
2.16.1 Freons® ............................................ 38
2.16.2 Halogens ........................................... 38
2.16.3 Noble gases ........................................ 38
2.16.4 Air ................................................ 38
2.16.5 Others ............................................. 38
2.17 Hydrate formation at 0°C .................................. 39
2.18 Mixtures .................................................. 39
2.18.1 Mixtures of the same type .......................... 39
2.18.2 Type I plus Type II ................................ 40
2.18.3 Azeotropy .......................................... 41
2.18.4 Mixtures with non-formers .......................... 42
2.19 Appendix 2A Water content of the fluid in equilibrium
with hydrate for pure components .......................... 44
References ..................................................... 49
Chapter three. Hand calculation methods ........................ 51
3.1 The gas gravity method .................................... 51
3.1.1 Verifying the approach .............................. 54
3.2 The K-Factor method ....................................... 57
3.2.1 Calculation algorithms ............................. 58
3.2.2 Liquid hydrocarbons ................................ 60
3.2.3 Computerization .................................... 61
3.2.4 Comments on the accuracy of the K-factor method .... 62
3.2.5 Mann et al ......................................... 64
3.3 Baillie-Wichert method .................................... 64
3.4 Other correlations ........................................ 67
3.4.1 Makogon ............................................ 71
3.4.2 Kobayashi et al .................................... 71
3.4.3 Motiee ............................................. 72
3.4.4 Østergaard et al ................................... 72
3.4.5 Towler and Mokhatab ................................ 72
3.5 Comments on all the methods ............................... 73
3.5.1 Water .............................................. 73
3.5.2 Non-formers ........................................ 74
3.5.3 Isobutane vs. n-butane ............................. 74
3.5.4 Quick comparison ................................... 75
3.5.5 Sour natural gas ................................... 77
3.7 Appendix ЗА Katz K-Factor charts .......................... 83
References ................................................ 93
Chapter four. Computer methods ................................. 95
4.1 Phase equilibrium ......................................... 95
4.2 van der Waals and Platteeuw ............................... 96
4.3 Parrish and Prausnitz ..................................... 97
4.4 Ng and Robinson ........................................... 98
4.5 Calculations .............................................. 98
4.5.1 Compositions ........................................ 99
4.6 Commercial software packages ............................. 100
4.7 The accuracy of these programs ........................... 100
4.7.1 Pure components ................................... 101
4.7.2 Mixtures .......................................... 104
4.7.3 Sour gas .......................................... 108
4.8 Dehydration .............................................. 109
4.9 Margin of error .......................................... 110
References .................................................... 112
Chapter five. Inhibiting hydrate formation with chemicals ..... 113
5.1 Freezing point depression ................................ 114
5.2 The Hammerschmidt equation ............................... 117
5.3 The Nielsen-Bucklin equation ............................. 119
5.4 Anew method .............................................. 119
5.4.1 A chart ........................................... 120
5.4.2 Accuracy of the new method ........................ 122
5.5 Brine solutions .......................................... 124
5.5.1 McCain method ...................................... 126
5.6 Østergaard et al ......................................... 126
5.7 Comment on the simple methods ............................ 130
5.8 Advanced calculation methods ............................. 130
5.9 A word of caution ........................................ 131
5.10 Ammonia .................................................. 132
5.11 Acetone .................................................. 132
5.12 Inhibitor vaporization ................................... 133
5.12.1 A more theoretical approach ....................... 135
5.12.2 Inhibitor losses to the hydrocarbon liquid ........ 137
5.13 A comment on injection rates ............................. 139
5.14 Safety considerations .................................... 139
5.15 Price for inhibitor chemicals ............................ 139
5.16 Low dosage hydrate inhibitors ............................ 140
5.16.1 Kinetic inhibitors ................................ 141
5.16.2 Anticoagulants .................................... 142
Bibliography .................................................. 148
References .................................................... 148
Chapter six. Dehydration of natural gas ....................... 151
6.1 Water content specification .............................. 151
6.2 Glycol dehydration ....................................... 152
6.2.1 Liquid desiccants ................................. 152
6.2.2 Process description ............................... 153
6.2.3 Short Cut Design Method ........................... 156
6.2.4 Approximate capital cost .......................... 159
6.3 Mole sieves .............................................. 160
6.3.1 Process description ............................... 160
6.3.2 Simplified modeling ............................... 160
6.4 Refrigeration ............................................ 164
6.4.1 Process description ............................... 165
6.4.2 Glycol injection .................................. 166
References .................................................... 169
Chapter seven. Combating hydrates using heat and pressure ..... 171
7.1 Plugs .................................................... 171
7.2 The use of heat .......................................... 172
7.2.1 Heat loss from a buried pipeline .................. 172
7.2.2 Line heater design ................................ 176
7.2.3 Two-phase heater transfer ......................... 179
7.3 De-pressurization ........................................ 179
7.4 Melting a plug with heat ................................. 181
7.5 Buildings ................................................ 183
7.6 Capital costs ............................................ 183
Appendix 7A Output from pipe heat loss program for the
examples in the text .......................................... 187
References .................................................... 200
Chapter eight. Physical properties of hydrates ................ 201
8.1 Molar mass ............................................... 201
8.2 Density .................................................. 202
8.3 Enthalpy of fusion ....................................... 203
8.4 Heat capacity ............................................ 205
8.5 Thermal conductivity ..................................... 205
8.6 Mechanical properties .................................... 205
8.7 Volume of gas in hydrate ................................. 205
8.8 Ice versus hydrate ....................................... 206
References .................................................... 210
Chapter nine. Phase diagrams .................................. 211
9.1 Phase rule ............................................... 211
9.2 Comments about phases .................................... 211
9.3 Single component systems ................................. 212
9.3.1 Water .............................................. 214
9.4 Binary systems ........................................... 214
9.4.1 Constructing T-x and P-x diagrams ................. 217
9.4.2 Methane+water ..................................... 217
9.4.3 Free-water ........................................ 220
9.4.4 Carbon dioxide water .............................. 220
9.4.5 Hydrogen sulfide + water .......................... 222
9.4.6 Propane + water ................................... 222
9.5 Phase behavior below 0°C ................................. 222
9.5.1 Methane + Water .................................... 222
9.6 Multicomponent systems ................................... 223
9.6.1 An acid gas mixture ............................... 224
9.6.2 A typical natural gas ............................. 225
References .................................................... 228
Chapter ten. Water content of natural gas ..................... 229
10.1 Equilibrium with liquid water ............................ 229
10.1.1 Ideal model ....................................... 230
10.1.2 McKetta-Wehe chart ................................ 231
10.1.3 Sharma-Campbell method ............................ 231
10.1.4 Bukacek ........................................... 234
10.1.5 Ning et al ........................................ 235
10.1.6 Maddox correction ................................. 237
10.1.7 Robinson et al. charts ............................ 240
10.1.8 Wichert correction ................................ 241
10.1.9 AQUAlibrium ....................................... 242
10.2 Equilibrium with solids .................................. 242
10.2.1 Ice ............................................... 242
10.2.2 Hydrate ........................................... 244
10.2.3 Methane ........................................... 244
10.2.4 Gas gravity ....................................... 245
10.2.5 Ethane ............................................ 248
10.2.6 Propane ........................................... 249
References ............................................... 254
Chapter eleven. Additional topics ............................. 255
11.1 Joule-Thomson expansion .................................. 255
11.1.1 Theoretical treatment ............................. 256
11.1.2 Ideal gas ......................................... 256
11.1.3 Real fluids ....................................... 257
11.2 Hydrate formation in the reservoir during production ..... 259
11.3 Flow in the well ......................................... 259
11.4 Transportation ........................................... 261
11.5 Natural occurrence of hydrates ........................... 262
11.5.1 Seabed ............................................ 262
11.5.2 Natural gas formations ............................ 263
11.5.3 Outer space ....................................... 264
References .................................................... 266
Appendix. Programs on the Accompanying Web Site ............... 269
Index ......................................................... 273
| 
