一种用于多级压裂水平井判别来水方向的多井干扰压力分析方法

A multi-well interference pressure transient analysis method to determine the water source orientation of multi-fractured horizontal well

为了确定直井注水、水平井采油的联合井网井间连通情况,建立考虑裂缝非均匀产液的多级压裂水平井多井干扰试井解释模型,运用Green函数、Newman乘积法得到井底压力解,绘制无量纲压力和压力导数典型曲线图版,进行参数敏感性分析。多级压裂水平井多井干扰试井模型典型曲线划分为7个流动阶段,其中在系统干扰流阶段,压力导数曲线下降,且注水井的注水量越大,其下降程度越大,当周围注水井的总注水量小于多级压裂水平井产量时,压力导数曲线呈阶梯状下降特征,最终表现为一条水平直线段,当周围注水井的总注水量大于观测井产量时,压力导数曲线将一直下降,呈现下掉特征;注水井到多级压裂水平井的距离越近,系统干扰流阶段持续的时间越长。实例应用表明,提出的模型能够确定注采井间连通情况、判别多级压裂水平井来水方向,指导油田开发措施的制定。

In order to determine the connectivity between injection wells and multi-fractured horizontal well(MFHW)accurately,a multi-well interference pressure transient analysis(MWIPTA)model was developed in this study,in which the effects of unequal liquid-production rate of fractures and the interferences from adjacent injection wells on pressure-transient behaviors were considered.The solutions of the model in terms of pressure drop were derived on the basis of the Green function and a Newman product method,and the characterization curves of bottomhole pressure were figured out along with a sensitivity analysis of important influencing factors.A typical MWIPTA curve can be divided into several flow regimes.In the interference flow regime,the pressure derivative curve will descend and higher injecting rate of the adjacent active wells can cause greater decline on the pressure derivative curve.When the total injection of the adjacent wells is smaller than the production of the MFHW,the pressure derivative curve will descend in a stepwise manner.When the total injection of the adjacent wells is bigger than the production of the MFHW,the pressure derivative curve will descend all the time.In addition,the closer distance between the MFHW and the adjacent injection wells,the longer interference flow regime will last.The results of a case study show that the model can be used to determine the connections between the injection wells and the MFHW and identify the water source orientation of the MFHW accurately,which can provide guidelines for increasing oil production of the MFHW.