Determination of Hydrate Phase Equilibrium Curve Using High-Pressure Visual Cell

Document Type : Research Note


Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163 Tehran, I.R. IRAN


This study aimed to construct the hydrate three-phase equilibrium curves for two typical Iranian gas reservoir samples using a high-pressure visual cell. To do so, complete analysis of the reservoir fluids was obtained by different techniques of composition analysis i.e. gas chromatography (GC) and detailed hydrocarbon analysis (DHA). Using high-pressure visual cell the hydrate phase equilibrium curve was obtained by measuring the hydrate formation temperature in each pressure level. By means of commercial hydrate software, hydrate formation temperature was predicted in each specified pressure level. Comparing the results showed that the experimental data are in good agreement with the simulator results. Using the experiments results, hydrate phase equilibrium curves were constructed in order to depict the safe and unsafe regions of the hydrate formation zones for two typical Iranian gas reservoir samples.


Main Subjects

[1] Sloan, E.D., Natural gas hydrates, Colorado School of Mines, SPE paper 2356, (1953).
[2] Hammerschmidt, E. G., Formation of Gas Hydrates in Natural Gas Transmission Lines., Ind.  Eng. Chem., 26, 851 (1934).
[3] Deaton, W. M., Frost E. M., Gas Hydrates and Their Relation to the Operation of Natural Gas Pipe Lines, U.S.B.M. Monograph 8 (1946).
[4] Davidson, D.W., Clathrate Hydrates in Water: A  Comprehensive Treatise, Hydrate, 2, Chap. 3, 115 (1973).
[5] Kobayashi, R., Vapor Liquid Equilibria in Binary Hydrocarbon-Water Systems, Ph.D. Thesis, Univ. of Mich., Ann Arbor, MI (1951).
[6] Hubbard,R.A., Campbell, J.M ., Recent developments in gas dehydration and hydrate inhibition, SPE paper 21507, (1992).
[7] Tohidi, B. et al., Measurement and prediction of hydrate-phase equilibrium for reservoir fluids, SPE paper 31234, (1994).
[8] Tohidi, B., Danesh, A., Todd, A.C., Predicting Pipeline Hydrate Formation, Chem. Engineer, September (1997).
[9] Tohidi, B. et al., Effect of Heavy Hydrate Formers on the Hydrate-Free Zone of Real Reservoir Fluids, paper SPE 35568, presented at the 1996 SPE European Production Operations Conference and Exhibition, Stavanger, 16-17 April, (1999).
[10] Tohidi, B. et al., Hydrate-Free Zone for Synthetic and Real Reservoir Fluids in the Presence of Saline Water, Chem. Eng. Sci., 2, p. 37 (1997).
[11] Ng, H.-E., Chen, C.J. and Saeterstad T., Hydrate Formation and Inhibition in Gas Condensate and Hydrocarbon Liquid Systems, Fluid Phase Equi-libria, 4, p. 22 (1987).
[12] Hammerschmidt, E.G., Formation of Gas Hydrates in Natural Gas Transmission Lines, Ind. Eng. Chem., 6, p. 12 (1934).