复杂小断块边水油藏采收率预测新方法

New method of predicting recovery ratio of the complex small fault blocks reservoirs with edge water

在复杂小断块边水油藏中,天然能量差异大,边水影响程度成为采收率预测的敏感因素,造成采收率预测准确率低。参考现有采收率标定经验关系式,筛选复杂小断块边水油藏采收率预测的主要影响因素;提出等效水井的概念,将边水能量的作用转化为边缘注水模式下水井的作用;借助数值模拟虚拟开发,应用多元回归确定了采收率标定经验关系式中各影响因素的系数;并从油层物理渗流机理角度对公式进行了修正。与以往的采收率标定经验关系式的预测结果对比可以看出:边水能量较弱时,二者预测的采收率误差较小,为0～13%;边水能量较强时,二者预测的采收率误差较大,为3%～88%。新建立的采收率标定经验关系式综合考虑了边水、驱油效率、储量动用和储层物性等因素,更符合复杂小断块边水油藏的实际,预测结果更合理。

The natural energy of the complex small fault block reservoirs with edge water is very different.The edge water has become the sensitive factor during the recovery ratio assessment,and it makes the assessment result inaccuracy.In this paper,the main influencing factors of predicting recovery ratio in the oil reservoirs were selected based on the current empirical relationship for recovery ratio assessment.And the concept of equivalent injection well was proposed,which used the peripheral water injection response of the injection wells to replace the affection on development effect of the edge water energy.Afterwards,numerical simulation was researched,and the parameters in the equations were determined with multiple regression method.The new re-covery equation was corrected based on the fluid flow mechanism.Compared with other empirical formulas,it shows that the recovery ratio error was 0-13% for the oil reservoirs of weak edge-water energy,and the recovery ratio error was 3%-88% for the oil reservoirs of strong edge-water energy.The new recovery equation was more conformed to the actual complex small fault block reservoirs with edge water,considered generally influencing factors,such as edge water energy,displacement effi-ciency,producing reserves,physical property of reservoirs and so on.It has good effect on the recovery forecasting for the com-plex small block reservoirs with edge water.