Institute of Petroleum Engineering

Centre for Gas Hydrate Research Publications



Abstract 052
Hydrate Phase Equilibria of a Near Critical Fluid - Effect of Formation Water, Methanol and Physical Separation
Østergaard, K. K., Tohidi, B., Burgass, R. W., Danesh, A., and Todd, A. C.
AIChE Journal, 47(7), 1683-1688 (2001).

The hydrate phase boundary of a near critical fluid (NCF) was measured in the 275 K-289 K temperature range in the presence of distilled water, synthetic formation water, and synthetic formation water with 10.41 wt% methanol. The results were compared with the predictions of an in-house thermodynamic model with excellent agreement. In order to simulate a typical oil/gas production scenario, the NCF was flashed at 298.1 K and 17.189 MPa, and the resulting liquid was subsequently flashed at 298.0 K and 4.089 MPa. The hydrate free zones of the resulting liquid fractions were measured to investigate the effect of physical separation on the hydrate phase boundary. The in-house thermodynamic model was used to simulate the separators conditions and to predict the hydrate free zone of the resulting liquid and vapour fractions. The predictions were in close agreement with the experimental data, demonstrating the reliability of the thermodynamic model. Furthermore, the results showed that the hydrate phase boundaries of the vapour and liquid phases resulted from physical separation are similar to that of the NCF.

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