碳酸盐岩缝洞型油藏单井注水替油开采的成功实践

塔河油田主要储渗空间为碳酸盐岩的岩溶缝-洞复合体，非均质性极强，多数井间不连通，油藏采收率仅有12％左右，其封闭型单井油藏年产量递减达到30%~90%、采收率仅有2.5%~5.5%. 在封闭型单井开展注水吞吐替油开采试验，利用重力分异原理注水置换替油并补充地层能量，提高这类油井的产能和采收率。数值模拟研究表明这种开采方式是可行的。通过对110 口井矿场试验与推广，注水132.18×10⁴ t、增油45.25×10⁴ t，单井初期日增油13~164 t、周期增油55~3 076 t，其中典型长停井X81 注水吞吐替油后采收率已提高了12.67 个百分点。

Successful Practice for Carbonate Reservoir Development by Cyclic Water Injection Process

Tahe oilfield is the largest carbonate reservoir characterized by complex of karst fractures and cavities, with strong lateral and vertical heterogeneity. Most wells in it are not hydrodynamicly connected. The primary oil recovery of single well in a blocked reservoir is as low as 2.5%～5.5% with 30%～90% production declined rate and the maximum oil recovery is only around 12%. For this reason, cyclic water injection process in single well is applied to the reservoir development as a pilot test in Tahe oilfield. The numerical simulation study indicates that this process is feasible and extended to the whole field. In 110 wells, the water injection rate amounts to 132.18×10⁴t, the incremental oil production reaches 45.25×10⁴t, showing the daily increased single well production rate ranges from 13 t to 164 t and the cyclic incremental production rate ranges from 55 t to 3 076 t. As a typical example, the dead production well, Well X81, has reached an extra 12.67% oil recovery following the cyclic water injection.