垂直井多分量感应测井大型三维有限差分模拟

The 3D Finite Difference Forward Modeling of Multicomponent Induction Log in Vertical Borehole

电性各向异性低电阻率储层的含水饱和度评价经常出现偏差,其原因在于对这种储层的评价没有综合考虑测井仪器的测量特性和地层电阻率方向上的差异。对垂直井,表征各向异性地层的参数主要有水平电阻率和垂直电阻率,但常规电法测井只提供地层水平方向的电阻率信息,不能直接测量地层垂直方向的电阻率。多分量感应测井直接用来测量电性各向异性地层的水平电阻率和垂直电阻率,从而可对各向异性储层进行较为客观的评价。简单介绍了多分量感应测井原理,推导了垂直井中进行三维有限差分模拟的计算公式。计算结果表明,该算法能较好地模拟三维地层模型。它对更深入研究多分量感应测井方法以及进行仪器研制打下了较好的基础。

Because measuring characteristics of logging tools and difference of formation resistivities in directions have not been considered synthetically, errors often arise in the saturation evaluation of electrical anisotropy reservoirs with low-resistivity. Both horizontal and vertical resistivities are used to characterize the electrical anisotropy reservoirs in vertical borehole, but conventional electrical logging tools are applied to measure horizontal resistivities not to provide vertical resistivities directly. A mul-ticomponent induction tool provides direct measurements to derive both horizontal and vertical resistivities that allow accurate evaluation of the anisotropy reservoirs. The principal of multicomponent induction log is introduced and the formulae simulating the tool responses by 3D finite difference method are derived in the paper. Several numerical results are presented to illustrate its effectiveness in 3D models. The method has laid a foundation for the further research of multicomponent induction log and design of the tool.