无因次注入-采出曲线法计算采收率方法改进

无因次注入-采出曲线法适用于水驱稳定阶段预测油藏最终采收率。在实际应用中，与其他采收率预测方法相比，其误差普遍偏大，参考价值较低。为提高无固次注入．采出曲线法预测采收率的实用性，对该方法进行了改进：据开发中后期注采平衡模型，当阶段产水量等于油藏废弃时的临界含水率乘以阶段注水量时，则确认水驱失效，重新推导了添加临界含水率限定条件的采收率求解过程。以X14油藏为例，演示了利用改进后的无因次注入-采出曲线法计算最终采收率的过程；在绥靖油田典型油藏中应用，预测结果的准确度相对改进前有了较大提高，验证了方法改进的可行性。

Improvement on dimensionless injection-production curve method to calculate ultimate recovery

The dimensionless injection-production curve method applies to calculate ultimate recovery at the waterflooding stable stage. Compared with the other oil recovery prediction methods, the errors of predictive value are larger with low reference value in practical application. To enhance the practicability of calculation results, the improvements of the method are proposed. According to the balanced injection model at late stage of development, the waterflooding is nearly invalid when stage water production equals to stage water injection multiplied by critical water cut. And, the solving process is deduced which added critical water cut qualification. It demonstrates the process which the improved dimensionless injection-production curve methods calculate ultimate recovery in the XI4 reservoir. The predicted accuracy of improved method is relatively higher than that of the former method, which verifies the feasibility of improved method when is applied in the typical reservoirs of Suijing Oilfield.