考虑缝间流量不对称的裂缝井干扰试井分析方法

Interference Well-test Model for Fractured Well Considering Rate Asymmetry along Fracture Wings

考虑压裂缝间的相互干扰作用,采用有限差分方法耦合地层与裂缝渗流方程,建立压裂井邻井干扰试井模型,绘制试井典型图版。分析裂缝表面线流量分布,由于存在缝间干扰,压裂井裂缝表面线流量呈非对称分布。同时,由于干扰井裂缝的高导压能力,模型中干扰信号将更快传导至观察井井底,压力导数曲线提前出现干扰过渡阶段。研究了观察井与干扰井布井方位的影响,当观察井与干扰井裂缝位于同一直线时,裂缝高导压作用最显著,其中裂缝半长的影响效果远大于裂缝导流能力。通过与商业软件数值试井模型对比,验证了模型的正确性。使用建立的模型解释了现场实例,曲线拟合效果好,解释结果合理,为判断井间连通性及制定开发调整措施提供了重要依据。

Considering the mutual interference between fractures of different wells,the finite-element method was introduced to solve the well test model for fractured wells with interference from adjacent well.A typical curve of well test was depicted.The distribution of dimensionless flow rate per unit of fracture length going from the formation into the fracture was analyzed.Due to the presence of inter-fracture interference,the flow rate across the fracture surface was no longer symmetrical.Considering the high pressure-conductivity ability of the interference well fracture,the interference signal was transmitted to the bottom of the observation well faster,and the pressure derivative curve appeared in the interference transition stage earlier.The effect of the orientation of observation wells and interference wells was studied.When the fractures of observation wells and interference well were on the same line,the high-conductivity of fractures had the most significant influence.Moreover,the effect of the fracture half-length was much greater than the fracture-conductivity.The results of proposed model are highly compatible with the results of numerical model in commercial well test software,which verifies the accuracy and applicability of the model.A field example is interpreted by our model.The interpretation parameters are reasonable,which indicates that our method is an effective tool for judging the connectivity between wells and formulating adjustment treatments for oilfield.