电性轴对称分布电阻率测井的有限元法模拟

FEM simulating logging with axial-symmetric resistivity distribution

针对石油勘探中需要精确确定沿井轴方向和径向电阻率变化的要求 ,提出了一种考虑地面影响且电阻率在纵向 (井轴 )上和径向上都分块均匀变化的测井二维有限单元法数值模拟方法 .采用异常电位法 ,使计算精度大大提高 ,并采用变带宽存储系数矩阵以节约内存 .经过与理论曲线对比证明此方法有效 .本方法有助于模拟复杂的地质情况 ,可以作为精确反演的基础 。

Considering the effect of ground and in accordance with axial symmetric resistivity distribution, a 2 D FEM (finite element method) using abnormal potential method to simulate logging is put forward in this paper, which makes use of variable bandwidth to store matrix of coefficients in order to save the internal memory. Its conductivity is homogeneous in each block.It is proved effective in term of good overlapping of theoretical curve and the curve derived from the method in this paper. Moreover, it can also be applied to method study as engineering physical survey near the earth surface.