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

摘要

It is traditionally considered in China that recovery ofcondensate gas reservoir cannot be improved by waterinjection. But, recently work abroad showed that it could begreatly improved by water injection. To address whether therecovery may be improved by water injection, a series ofexperiments are performed based on the preliminary PVT test.The experiments employed about 1m long-core and compoundcondensate fluid obtained from Ban 2 Group abandoncondensate gas reservoir of DaGang oil field, CNPC. Thestudies include three main parts: (1) depleting the condensatereservoir to abandon pressure 8Mpa at different velocity tostudy on the rate effect of recovery. (2) Injecting water intocore after pressure reach abandon pressure (3) increasing thepressure to 20MPa by water injection and then keep injectionand production balance to study on further condensate and gasrecovery. The study showed that condensate recoverymeasured in PVT cell is half of that tested in long-core, theresult is concordant with the practical conditions; explorationby keeping injection and production balance under abandonpressure can further increased condensate recovery by 3.39%and gas recovery by 10.11% and condensate recovery increasewith the increase of water injection velocity; balanceproduction under recovered pressure can further increasedcondensate recovery by 0.68% and natural gas recovery by5.39%. In-situ test showed that after re-injecting 135×10~4m~3wastewater into abandon condensate gas reservoir, further8006t condensate oil and 4885 × 10~4m~3 natural gas wereproduced to Oct. 2002. The study highlights good economyprofits as well as environmental friendly by water injection.