井间电磁测量数据的模拟与处理解释  

Modeling and Processing of the Cross-hole Electromagnetic Measurements and Their Interpretation

作　　者：沈金松[1] 孙文博[1] 赵文杰[2] 曾文冲[2] 

机构地区：[1]中国石油大学资源与信息学院 [2]中国石化胜利油田测井公司,山东东营257001

出　　处：《测井技术》2007年第5期417-424,共8页Well Logging Technology

摘　　要：用有限元法模拟了偶极子源在二维介质中的频率域井间电磁响应。针对测量区域的层状地层分布特征,沿构造走向(y-轴方向)作Fourier变换,将全三维电磁场问题转化为一系列二维问题在波数域求解,极大地减小了计算量,使实际测量数据的处理解释成为可能。针对波数域中波数取值对模拟结果的影响,采用三次样条插值加密波数域数据,用高斯积分实现Fourier逆变换将波数域解变换为空间域电磁场。采用具有一定面积的伪δ函数表示源电流分布,避开了源点的奇异性,使数值解精度得以提高。通过对中国东部某油田2口井的实测井间电磁数据的模拟与处理解释,验证了该算法的有效性,为井间电磁数据的反演解释奠定了基础。A finite element method is developed for simulating frequency domain cross-hole electromagnetic responses due to a dipole source in 2D conductivity structure. A Fourier transform along the direction of the structure （y-axis） based on characters of bedded layers in the studied area is used to convert the original full 3-D electromagnetic field problem to a series of 2D problems to be solved in y-wave number （Ky） domain. It decreases computing cost considerably and so that process of practical field data becomes possible. Having considered the effect of wave number setting on the numerical calculation result, the cubic spline interpolation method has been used to infill data in the wave number domain. An inverse Fourier transform realized by Gaussian integral method converts the Ky domain solutions to electromagnetic fields in real space. A pseudo delta-function with finite region is utilized in modeling distribution of the dipole source current to obviate the singularity of the source point, so that the accuracy of the numeric solution is enhanced. The effectiveness of the method is verified by results of modeling, processing and interpreting practical cross-hole electromagnetic data acquired from two boreholes in an oil field of east China, so that the method could be as a foundation of inverting cross-hole electromagnetic data.

关 键 词：井间电磁数据处理解释 频率域 有限元法 波数域解 伪δ函数 

分 类 号：P631.32[天文地球—地质矿产勘探]