陆相砂岩油藏特高含水期开发指标变化规律

Development indexes variation law of continental sandstone reservoirs in ultra-high water cut stage

针对传统线性特征的驱替曲线都不再适用于特高含水期油藏的情况,提出了一种综合含水率和采出程度之间的非线性关系方程式,可直接描述特高含水期油藏宏观开发指标变化规律或驱替特征。结果表明:不管油藏曾经历的开采历史是否存在水驱井网加密、聚合物驱等重大调整措施,只要油藏在特高含水期处于相对平稳的开发状态,采出程度与综合含水率呈非线性关系。所提非线性关系得到了水驱油藏概念模型模拟结果的验证,已用于含聚驱历史真实油藏开发后期的指标分析。对于陆相大型油田的部分开采单元及其整体,该关系在特高含水期大部分呈现出90%以上的符合率,由此得到了值得油田中长期规划参考的含水上升率、递减率、采收率等开发指标预测结果。

Aiming at the situation that traditional displacement curves with certain linear characteristics are no longer applicable in ultra-high water cut stage,a nonlinear relationship between comprehensive water cut and recovery of OOIP is proposed,which can directly describe the variation law of macroscopic development indexes or displacement characteristics of reservoirs in ultra-high water cut stage.The results show that,no matter whether there are major adjustment such as water drive well pattern infilling and polymer flooding in the reservoir production history,as long as the reservoir is in relatively stable development state in ultra-high water cut stage,there is a non-linear relationship between recovery degree and water cut.The proposed nonlinear relationship is verified by reservoir simulation results of water driven reservoir conceptual model,and is used for index analysis of the later development stage of real reservoir with polymer flooding history.For some production units and the whole of large continental oilfield,the relationship also shows most of the coincidence rates>90% in ultra-high water cut stage,thus obtaining the prediction results of development indexes of water cut increase rate,decline rate and recovery rate,providing reference for medium and long-term planning of oilfield.