摘要
从电磁响应方程出发 ,应用交错网格有限差分法推导了各向异性地层三维电磁响应的差分计算格式。应用该计算方法进行了多种环境下电磁响应的计算。计算结果表明 ,在直井水平层中 ,磁场强度分量与地层水平电阻率和垂直电阻率有关 ,磁场强度分量只与地层水平电阻率有关 ;当地层或井眼倾斜时 ,线圈测量值与地层水平电阻率和垂直电阻率均有关 ;线圈测量值受趋肤效应影响与线圈距有关 ,线圈距越大 ,受趋肤效应影响越严重 ;场强度分量对地层界面很敏感 ,受趋肤效应的影响比磁场分量大 ;已知各测量值可反演出地层水平电阻率和垂直电阻率 ,进而改善电性各向异性低阻储层的含油饱和度评价。
The difference formats to compute 3-D electromagnetic responses to anisotropic formation are derived from the Maxwell’s equations by using staggered-grid finite difference method. The obtained results show the formulae are correct. The difference formats have been applied to investigate the laws of electromagnetic responses in various environments. In the horizontal layers in vertical wells, the magnetic field strength components H xx and H yy are related with horizontal and vertical resistivities, but the component H zz is only related with the horizontal resistivity. When the formation or borehole is declinate, the components with different coil distances are related with horizontal and vertical resistivities, and the larger the coil distances, the much influence of skin effect on the components. The components H xx and H yy are very sensitive to the formation boundaries, so they are more easily influenced by the skin effect than H zz . The exact calculation of horizontal and vertical resistivities is crucial to improve the evaluation of anisotropic reservoirs with low resistivities.
出处
《测井技术》
CAS
CSCD
2004年第3期191-195,共5页
Well Logging Technology
基金
国家自然科学基金资助项目 (No.40 2 740 1 8)
关键词
电磁散射响应
各向异性
交错网格
有限差分法
应用
电阻率
electromagnetic scattering response
anisotropy
staggered grid
finite difference method
application
resistivity
