低渗透油田注水与注气开发的数值模拟比较

Comparison of Numerical Simulation Results of Water Flooding with Gas Injection in Low permeability Reservoirs

为了搞清楚低渗透油田注水和注气开发的效益，以安塞油田坪桥区特低渗透油田为例，应用三维三相全组份模型，对低渗透油田的注水开发和注气开发进行了数值模拟研究，并将二者进行了对比，结果表明，注水开发和注气开发都能有效地向地层补充能量，较自然能量开采，开发水平有很大提高，是开发低渗透油田的有效方法；注水开发和注气开发比较存在三个时期，即①前期注水优于注气；②中期注气优于注水；③后期注水优于注气；三个不同时期出现的早晚和长短受注入气组成的影响；注水采收率可达２６．２４％；注气采收率在１４．１４％～２４．２８％之间，注入气体越富，效果越好；提高注气效果的关键，是延迟注入气在生产井井底的突破．

Taking the low permeability reservoir of Pingqiao Area in Ansai Oil Field as an example, the results of water flooding and gas injection are numerically simulated with 3D 3P Full compositional simulator, and the simulation results are compared. It is shown that, (1) the results of both water flooding and gas injection are better than that of natural development. (2) the processes of water flooding and gas injection can be divided into three stages according to the simulation results, in the first and last stages, the result of water flooding is better than that of gas injection, but in the middle stage, gas injection is better than water flooding. The start times and the durations of the three stages depend on the composition of injected gas. (3) the recovery factor of water flooding can reach to 26.24%, the recovery factor of gas injection is in the range of 14.14%￣24.28%, and the richer the injected gas, the higher the recovery factor. (4) the key to increasing recovery factor is to delay the breakthrough of injected gas at the bottom of producing well.