Experimental Studies on Injecting Wastewater to Improve the Recovery of Abandon Condensate Gas Reservoir

Abstract

Abstract It is traditionally considered in China that recovery of condensate gas reservoir cannot be improved by water injection. But, recently work abroad showed that it could be greatly improved by water injection. To address whether the recovery may be improved by water injection, a series of experiments are performed based on the preliminary PVT test. The experiments employed about 1m long-core and compound condensate fluid obtained from Ban 2 Group abandon condensate gas reservoir of DaGang oil field, CNPC. The studies include three main parts: (1) depleting the condensate reservoir to abandon pressure 8Mpa at different velocity to study on the rate effect of recovery. (2) Injecting water into core after pressure reach abandon pressure (3) increasing the pressure to 20MPa by water injection and then keep injection and production balance to study on further condensate and gas recovery. The study showed that condensate recovery measured in PVT cell is half of that tested in long-core, the result is concordant with the practical conditions; exploration by keeping injection and production balance under abandon pressure can further increased condensate recovery by 3.39% and gas recovery by 10.11% and condensate recovery increase with the increase of water injection velocity; balance production under recovered pressure can further increased condensate recovery by 0.68% and natural gas recovery by 5.39%. In-situ test showed that after re-injecting 135×104m3 wastewater into abandon condensate gas reservoir, further 8006t condensate oil and 4885 × 104m3 natural gas were produced to Oct. 2002. The study highlights good economy profits as well as environmental friendly by water injection.