Page 223 - Handbook Of Multiphase Flow Assurance

222 10. Research methods in flow assurance

Experimental study of hydrate Summary of simulations 338
crystal growth 299 Summary from the adsorption
Morphology of hydrate crystals 299 simulation results 340
Effect of adding kinetic hydrate Conclusions about kinetic
inhibitors on the morphology of inhibition mechanism 341
growing hydrate 304 Recommendations 341
Effect of NaCL salt on THF hydrates 308 Flow loop tests 341
THF + water + inhibitors solution
with NaCL salt 312 Bench scale tests 342
Growth rate measurements 312 Paraffin cold fingers 342
Paraffin cross-polarized microscope CPM 342
Computer modeling of interaction Rheology 343
between a hydrate surface and an DSC 343
inhibitor 312 Raman spectroscopy 343
Organization of this section 312
Early modeling of clathrate Computer code 343
hydrates at CSM 313 Program for generating radial
Studies of monomers adsorption distribution function in water 343
on hydrate with cerius2 313 Program for h bonded rings count
Using the hand-written software in water 346
for studying interaction of water Monte carlo program for polymer
and monomers 320 adsorption on hydrate 367
Adsorption of inhibitor polymers References 436
on hydrate 329
Using the computer to design inhibitors 336 Further reading 441

Hydrate stability and crystal growth

This section describes measurement of thermodynamic equilibria for methane sI hydrate
formation, which were measured in a temperature interval of 190–262 K. No structural hydrate
phase transition occurred in the studied region. Methane hydrate remained as structure I.
Thermodynamic equilibria of xenon sI hydrate and xenon + neohexane sH hydrate forma-
tion were studied. The temperature interval was from 228 to 288 K for sI hydrate and from 233
to 288 K for sH hydrate. A quintuple point sH-sI-Lw-Lh-V was determined to be at 281.5 K.

Importance of studying gas hydrates

Gas hydrates are inclusion crystalline compounds. Hydrates may form when a mixture
of water and gas molecules is subjected to specific temperature and pressure. Usually, the
pressure of gas hydrate formation is high (above 10 psi) and temperature is low (below 50 °F).
Temperature and pressure of hydrate formation may be dependent or independent variables,
depending on the number of components and phases in system.
Gas hydrates have an increasingly important place in the oil and gas industry. They may
serve in the future as the principal source of hydrocarbon fuel. One of the estimates suggests
3
5
16
that gas hydrate deposits worldwide are about 2 × 10 m or 7 × 10 Tcf. This is roughly two
times the amount of carbon in all other known fossil fuel deposits.