Methane Hydrate Dissociation by Depressurization in a Mount Elbert Sandstone Sample: Experimental Observations and Numerical Simulations

• Main Authors: Kneafsey, T., Moridis, G.J.
• Language: unknown
• Published: 2012
• Subjects: 54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; CAT SCANNING; DEPRESSURIZATION; DISSOCIATION; EXPLORATORY WELLS; GAS HYDRATES; GRAIN SIZE; HEAT TRANSFER; HYDRATES; MONITORING; POROSITY; PRESSURE VESSELS; PRODUCTION; SANDSTONES; SIMULATION; SPATIAL RESOLUTION; STABILITY; Ice Point; Methane hydrate
• Online Access: http://www.osti.gov/servlets/purl/1048275; https://www.osti.gov/biblio/1048275

A preserved sample of hydrate-bearing sandstone from the Mount Elbert Test Well was dissociated by depressurization while monitoring the internal temperature of the sample in two locations and the density changes at high spatial resolution using x-ray CT scanning. The sample contained two distinct regions having different porosity and grain size distributions. The hydrate dissociation occurred initially throughout the sample as a result of depressing the pressure below the stability pressure. This initial stage reduced the temperature to the equilibrium point, which was maintained above the ice point. After that, dissociation occurred from the outside in as a result of heat transfer from the controlled temperature bath surrounding the pressure vessel. Numerical modeling of the test using TOUGH+HYDRATE yielded a gas production curve that closely matches the experimentally measured curve.