致密低渗透气藏压裂水平井产能计算与分析

Fractured Horizontal Well Productivity Forecast and Analysis in Low-Permeability Tight Gas Reservoir

为准确预测致密低渗透气藏压裂水平井产能,利用保角变换对渗流场变换,建立考虑压敏效应和启动压力梯度的渗流方程,积分得到压力函数降,并利用叠加原理建立压裂水平井产能模型。结果表明:产能模型与试采产能的误差为8.26%,产能模型准确可靠;压敏效应对产能的影响大于启动压力梯度对产能的影响;裂缝多于3条时,产能增加幅度变缓;增加裂缝长度和中间裂缝间距有利于提高产能。该模型为致密低渗透气藏压裂水平井产能预测和压裂参数优化提供了借鉴。

In order to accurately forecast the productivity of fractured horizontal well in low-permeability tight gas reservoir,conformal transformation is used to deduce a seepage equation considering the effects of pressure-sensitive and starting pressure gradient. The pressure drop function is gained by integrating the seepage equation and superposition principle is used to establish a productivity forecast model of fractured horizontal well. Research demonstrates that the relative error between forecasted productivity and production-test productivity is 8. 26% and the productivity forecast model is reliable and accurate. Productivity is more dependent on pressure-sensitive effect rather than starting pressure gradient. The productivity increases slowly when the number of fractures exceeds 3. Increasing fracture length and fracturing spacing are favorable to increase productivity. This productivity forecast model could provide a reference for the productivity forecast and fracturing optimization of horizontal wells in low-permeability tight gas reservoir.