Warm Water Flooding of Unconfined Gas Hydrate Reservoirs

Abstract

Large quantities 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 marine hydrate deposits. A multiphase, multicomponent, thermal, 3D simulator is used to simulate production of hydrates 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 of unconfined, horizontal and dipping reservoirs have been simulated. Production of methane from gas hydrate reservoirs depends on reservoir confinement, injection temperature, injection pressure, and production pressure. For unconfined horizontal reservoirs, depressurization is ineffective; thermal stimulation is necessary for gas production. Even warm water (temperature ≈ 30 °C) injection improves the gas production from hydrate reservoirs. Lower vertical permeability helps the gas production by heating a larger area of the reservoir for hydrate dissociation. As the well spacing decreases, the gas 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 shorter.

Experimental investigation of methane hydrate formation on suspended water droplets

“…Natural gas hydrate deposits, usually discovered under the seafloor or in the permafrost, are considered as a huge amount of potential energy for the 21st century [2,3]. At present, the exploration of natural gas hydrate deposits is intensively studied [4][5][6][7]. Gas hydrate formation is also a problem that the oil and gas industry are concerned with.…”

Using Submarine Heat Pumps for Efficient Gas Production from Seabed Hydrate Reservoirs

“…Almost the same idea was proposed in a simulation study by Phirani et al [15]. However, it is not clear if the construction of such a water-circulation loop below the seabed close to the hydrate reservoir is technically feasible.…”

Gas production from layered methane hydrate reservoirs

“…For unconfined reservoirs, thermal stimulation is necessary as depressurization is difficult. Phirani et al [21] used warm water injection for thermal stimulation in unconfined reservoirs. Inhibitor injection is another suggested method for gas hydrate reservoirs.…”