中文摘要：

井—地电位法是利用地下储层注水后岩层电阻率的变化来研究储层剩余油分布和注水的推进前沿、判断油田的注水分布和剩余油分布的一种地球物理方法。本文阐述了井—地电位法监测地下注水裂隙的方法原理,研究和推导了水平管状注水裂隙的井——地电位异常的理论公式,建立了地下裂隙模型并在Matlab中计算地下不同长度、深度和方位的地下裂隙在地面的理论视纯异常值,画出了注水前后电位差视纯异常玫瑰图。数值模拟结果表明,水平管状注水裂隙的井——地电位法视纯异常玫瑰图呈苹果状曲线分布,视纯异常的最小值对应的是苹果状曲线的根部,苹果状曲线的根部所指向的方位对应的就是地下注水裂隙的方位。在供电电流为15A,地下裂隙深度在500 m,裂隙长度为50～100 m时,井——地电位法视纯异常的变化幅值在n×10nV～n×100nV之间。井——地电位法视纯异常的形状、幅值随着水平管状注水裂隙的方位、长度和深度的变化而变化,因此,可以采用井——地电位法,监测地下水平注水裂隙的方位、长度和深度情况,从而为监测地下注水裂隙的注水情况及剩余油的分布情况提供地球物理资料。

英文摘要：

Well-ground potential method is usually used to detect the distribution of residual oil and the front of injected steaming water in reservoirs based on the resistivity difference before and after injecting.Firstly,the paper introduces the principle of the well-ground potential method for homogeneous half-space media,then deduces the formula of the ground potentials for steaming crack which is supposed to be the theoretical conduct.The numerical modeling results using MATLAB program are analyzed and plotted as rose shaped curves for different lengths,depths and angles.The numerical modeling results show that rose shaped map of horizontal crack is the similar to the shape of apple,and the minimum value of the pure anomaly is corresponding to the direction of the crack.The change of amplitude of well-potential anomaly is about n×10nV～n×100nV with crack depth 500m,crack length 50～100m,and injected current 15 A.The results show that the shape and amplitude of well-potential anomaly is changed with different direction,length and depth of the horizon tubular crack,which indicates the well-ground potential method that can be effectively used for indexing the direction,depth and length of the horizontal tubular crack.