关键词: 低渗气藏, 压裂井, 产能方程, 变启动压力梯度, 应力敏感, 滑脱效应

Abstract:

In order to accurately predict the well capacity in the fracture of the low permeability gas reservoir, it is necessary to consider the multi-factors. The studies show that the relation between the threshold pressure gradient and the average reservoir permeability of the low permeability gas reservoir is the power function. The deformation of the media function makes the stress sensitive effect more serious, and the slippage effect makes the gas seepage resistance down and increases the well productivity. According to the conformal transformation theory, we established a prediction model of fracturing well productivity, which considered the stress sensitivity, the slippage effect and the changed threshold pressure gradient, and studied the effects on the productivity. The results showed that, with the increase of the stress sensitivity coefficient, the gas well output decreases, and the pressure of the low well bottom flow is more affected. The lower the flow pressure of the bottom hole is, the more obvious the gas well output changes with the increase of slip coefficient. The threshold pressure gradient factors greatly affect the well productivity in a certain range. Therefore, it is necessary to consider the influence of many factors on the gas well productivity in the prediction of the production capacity of the low permeability gas reservoir.

Key words: low permeability gas reservoir, fracturing well, productivity equation, variable threshold pressure gradient, stress sensitivity, slippage effect