低渗透岩石渗透率与有效围压关系的实验研究

为研究低渗透岩石的流固耦合渗流规律,采用FDES-641驱替评价系统对采自长庆油田的砂岩岩样进行实验和分析。实验结果表明:低渗透岩石渗流过程中存在明显的流固耦合效应。随着有效围压的增加,岩样的渗透率逐步下降,当有效围压开始卸载,岩心的渗透率逐步得到恢复,但不能恢复到原始数据;低渗透岩石渗透率与有效围压之间的关系可以用一元二次多项式来描述;岩样渗透率变化的原因主要缘自在有效围压作用下岩石孔隙的变形特性。

Experimental study of the laws between the effective confirming pressure and rock permeability

The effect of fluid-solid coupling on the seepage in low permeability rocks was measured for sandstone from the Changqing oil field on an FDES-641 triaxial system. The results indicated coupling between the seepage and the permeability in low permeability rock. For example, increasing pressures reduced the rock permeability. The permeability recovered to some extent when the pressure was reduced, but did not return to the original value even when the pressure was completely released. The functional relationslip between the seepage and the effective confirming pressure and the rock permeability was fit by a polynomial. Changes in the characteristics of the pores and fractures existing in the rock as the pressure changes are expected to be the main causes of the rock permeability variation.