致密气藏水平井产量预测及影响因素分析

致密砂岩气藏具有极低的孔隙度、渗透率以及高有效应力等特征，其气水渗流规律并不满足传统意义上的经典渗流理论。针对致密砂岩气藏渗流特征，结合水平井渗流场特征，将水平井渗流区域划分为近井非达西流动区域和远井达西流动区域，并综合考虑启动压力梯度、滑脱效应和应力敏感效应的影响，推导出致密砂岩气藏水平井产能方程。并以某致密砂岩气藏为例，研究这3 个因素对致密砂岩气藏水平井产能的影响。结果表明：（1）启动压力梯度对水平井产能影响呈线性下降关系，应力敏感效应呈幂函数下降关系，而滑脱效应呈近似上升趋势；（2）应力敏感效应比启动压力梯度对水平气井产能影响更为强烈，而滑脱效应影响相对较小。

Analysis of Productivity Equation and Influence Factors of Horizontal Wells in Tight Sand Gas Reservoir

The traditional flow laws are inapplicable to the tight sand gas reservoirs because of the reservoirs’ rather lowporosity，low permeability and the high effective stresses. On account of the tight gas flow features and flow fields around thehorizontal wells，the horizontal well flow zone is divided into two areas：the near-wellbore area，which is non-Darcy flow，and the far-away area from the wellbore，which is Darcy Flow. Based on the study of this division，start-up pressure gradient，slippage effect and stress sensitivity，the productivity equation of horizontal wells in tight sand gas reservoirs was derived. Acase study is presented with the detailed studies on the three factors which impact the tight gas reservoir. With the equationand the case study analysis，the results indicate that：（1）productivity of horizontal wells in tight sand gas reservoirs decreaseswith start-up pressure gradient and stress sensitivity at a linear and an exponential relationship，respectively，but increases withslippage effect at a near-linear relationship；（2）the stress sensitivity has a stronger impact on the productivity compared withthe start-up pressure gradient，and the influence of slippage effect is relatively small.