考虑多种效应的致密气藏不对称裂缝井产能模型

Productivity Model for Asymmetric Fractured Wells in Tight Gas Reservoirs Considering Multiple Effects

致密储层地质条件复杂,在非均匀应力分布作用下,水力压裂后储层会形成单个甚至多个非对称裂缝。针对致密气藏储层改造后形成的多条非对称裂缝,应用保角变换原理,基于稳定渗流理论,推导了考虑启动压力梯度、应力敏感效应及滑脱效应3种因素影响下的非对称压裂气井无限导流能力产能数学模型,并分析了阈压梯度、压敏系数、滑脱因子以及裂缝非对称率等对压裂致密气井产能的影响。结果表明,随着启动压力和应力敏感性的增加,气井产能降低;随着滑脱效应及裂缝非对称率的增大,气井产能增加。

The geologic condition of tight gas reservoirs is complex. Under the effect of uneven distributed crustal stress of fi）r- marion, there will form a single or multiple asymmetric cracks in the formation after hydraulic fracturing. According to the a- symmetrical fractures after fracturing treatment, a tight gas well productivity prediction model was established based on stable seepage theory. We applied the method of conformal transformation while taking the effect of threshold pressure, stress sensi- tivity and slippage effect into consideration. And then analyze extend of impact to the tight gas well capacity of each factor. Results showed that the productivity of double fractured tight gas well decreases with the increase of start-up pressure and stress sensitivity; While the productivity increases with the increase of slippage effect factor and fracture asymmetry index.