Relative Permeability Measurements of Gas-water-hydrate Systems
Namit J. Jaiswal, Abhijit Y. Dandekar, Shirish L. Patil, Robert B. Hunter, Timothy S. Collett, 2009. "Relative Permeability Measurements of Gas-water-hydrate Systems", Natural Gas Hydrates—Energy Resource Potential and Associated Geologic Hazards, T. Collett, A. Johnson, C. Knapp, R. Boswell
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A primary mechanism likely to control potential gas production from gas-hydrate-bearing porous media is the gas-water two-phase flow during dissociation. Gas-water relative-permeability functions within gas-hydrate systems are poorly understood, and direct measurements within gas-hydrate-bearing porous media are difficult. In this study, we developed a new method for measuring gas-water relative permeability for laboratory-synthesized gas hydrate within porous media. The new experimental design allows gas hydrate to form within a porous media and allows the measurement of effective permeability and relative permeability for different saturation values. The relative permeability to gas and water was determined by applying the Johnson-Bossler-Neumann method. Finally, effective permeability and relative permeability data of gas and water phases are reported for gas-hydrate-saturated consolidated Oklahoma 100-mesh sand and Alaska North Slope subsurface sediments.
The results show significant reduction in permeability at increased gas-hydrate saturations. The results also suggest that the relative permeability determined from the unsteady-state core floods is primarily affected by gas-hydrate saturations. Furthermore, effective as well as relative permeabilities vary by the nature of gas-hydrate distribution for the same bulk saturation in different porous media. We believe that the experimental data obtained from this work will provide input data to reservoir modeling, fluid flow modeling, and development of relative-permeability-estimation methods for hydrate production. However, considerable additional experimental and theoretical work remains to develop an analytical or generalized model to predict the relative permeability for gas-hydrate reservoir simulation.