低渗气藏滑脱效应对启动压力梯度的影响试验研究

Experimental Study on the Influence of Slippage Effect on Threshold Pressure Gradient in Low Permeability Gas Reservoir

摘要: 致密多孔介质气体渗流，启动压力梯度和滑脱效应同时存在。为了研究低渗气藏中滑脱效应对启动压力梯度的影响，本文基于渗流力学理论，采用试验的方法对王营煤矿煤样进行渗流试验。通过试验数据拟合分别求得了启动压力梯度和体现滑脱效应的滑脱因子。结果表明，随着滑脱因子的增大，启动压力梯度逐渐减小，并且和滑脱因子呈现很好的线性负相关关系。说明滑脱效应越明显，越有利于气体的流动，从而启动压力梯度减小。因此建立滑脱因子–启动压力梯度试验模型，对提高煤层气的开采具有一定的指导意义。

Abstract: Gas seepage in dense porous media, threshold pressure gradient and slippage effect exist at the same time. In order to study the effect of slippage effect on the threshold pressure gradient in low permeability gas reservoir, based on the percolation theory, this paper adopts the experimental methodology to study the coal samples in Wangying coal mine in order to conduct seepage test. By the test data fitting, the slippage factor of threshold pressure gradient and slippage effect is obtained respectively. The results show that as the slippage factor increases, the threshold pressure gradient decreases gradually, and there is a good linear negative correlation with the slippage factor. It is indicated that the more obvious the slippage effect is, the more favorable the flow of gas is, and thus the pressure gradient will be reduced. So it is of guiding significance to establish the test model of slippage factor-threshold pressure gradient for improving the mining of coal bed methane.