低渗透油藏产量递减规律及水驱特征曲线

Production decline law and water drive characteristic curves in low permeability reservoirs

常规产量递减规律和水驱特征曲线不能很好地反映低渗透油藏的生产特征。针对低渗透油藏的基本特性，利用低渗透的渗流理论，推导出低渗透油藏产量递减方程和水驱特征曲线方程。由分析得出：进行低渗透油藏的产量递减、低渗透油藏的含水率和水驱曲线分析时，必须考虑启动压力的影响。启动压力越大，初始产量越小，但有启动压力的递减速率比没有启动压力的递减速率要小；且累计产量随启动压力的增大而减小。在其它相同情况下，当启动压力梯度越大时，含水率就越大。启动压力梯度影响低渗透水驱油藏水驱曲线。表1参5（杨正明摘）

Conventional Production decline law and water Drive characteristic curves incorrectly reflect the production featrue Of low permeability resrvoirs. In this paper, using the precolation Law and the essential characteristic of low permeability reservoirs, The authors set up the production production decline equations and water drive Characteristic equations of low permeability reservoirs. Some helpful Conclusion is drawn. When the production decline, water cut and Water drive characteristic curves are analyzed, the effect of the Threshold pressure must be considered. The higher the threshold Pressure, the smaller the initial production, and the decline rate With the threshold pressure is less than the decline rate without the Threshold pressure, and the cumulative production becomes smaller With threshold pressure increasing. In same condition except the Threshold pressure gradient, when the threshold pressure gradient Becomes bigger, water cut becomes bigger, and the threshold Pressure gradient affects water drive characteristic curves of low Permeability reservoirs.