挥发性油藏注天然气开发指标预测新模型

摘要

挥发性油藏注天然气极易形成混相驱，注气突破后油藏中非混相和混相驱同时存在，并动态变化。基于多个挥发油藏注天然气开发的生产曲线，推导了累积产油量变化的微分方程，并在此基础上提出了采出程度和气油比关系方程，可以预测不同生产气油比时的采出程度。同时提出了一种新型的气驱特征曲线，即注气达到一定阶段后，累积注气量的对数与累积产油量满足线性关系，该方程可以预测不同注气量下的累积产油量。经过实例分析和计算，表明该方法预测精度较高，具有较好的适用性和可行性。%Natural gas injection in volatile reservoir is easy to be miscible. After gas injection breakthrough, immiscible and misci-ble flooding coexist in the reservoir and change dynamically. Based on production curves of volatile reservoirs developed with natu-ral gas injection, the differential equation of cumulative oil production variation is deduced and the equation of degree of reserve re-covery with GOR is put forward to predict the relation between them. Meanwhile, a new gas drive characteristic curve is proposed. That is, after gas injection reaches a certain phase, there exists the linear relation between logarithm of cumulative gas injection vol-ume and cumulative oil production, and the equation can be used to predict the cumulative oil production under different gas injec-tion volume. The results of examples’analysis and calculation indicate that this forecasting method has higher accuracy, and better serviceability and feasibility.