Energy & Fuels, Vol.23, 4507-4514, 2009
Warm Water Flooding of Unconfined Gas Hydrate Reservoirs
Large qnantities of natural gas hydrates are present in shallow marine sediments as well as in arctic regions. This research is aimed at assessing production of natural gas from unconfined marin hydrate deposits. A maltiphase, multicomponent, thermal, 3D simulator is used to simulate production of hydrate in the equilibrium mode. Three components (hydrate, methane, and water) and four phases (hydrate, gas, aqueous-phase and ice) are considered in the simulator. Depressurization and warm water flooding o f unconfined, horizontal and dipping reservoirs have been simulated. Production of methane from gas hydrata resevoirs depends on reservoir confinement, injection temperature, injection presuure, and production pressure. For unconfined horizontal reservoirs, depressurization is ineffective: thermal stimulation is necessary for gas production. Even warm water (temperature approximate to 30 degrees C) injection improves the gas production from hydrate reservoirs, Lower vertical permeability helps the gas production by heating it larger area of the reservoir for hydrate dissociation. As the well spacing decreases, the p production rate increases. Depressurization alone is effective in dipping unconfined reservoirs, but much slower than warm water injection. As the injection point of the warm water moves down the reservoir, the start of the high gas recovery phase gets delayed, but the time for completion of gas recovery becomes