随钻超深多分量电磁传播电阻率测井三维正反演算法与电阻率成像技术研究

The ultra deep multi-component electromagnetic (EM) propagation resistivity logging while drilling(LWD) has very deep investigation depth. It will become a very important tool for the evaluation of complex reserviors, optimazation of well placement, geosteering and fine description of complex reserviors since it has potential ability to provide information about the horizontal and vertical conduntivity of invasion zone and virgin formation, and the spatial distribution of formation conductivity in excess of 35m radial depth of well path at same time. . In this project, aiming to the contruction and its deep investigation depth of the LWD ultra deep multicomponent EM propagation resistivity tool, we first introduce some new tecniques such as the optimal Yee staggered meshs, the standard homogenization and the direct solution of large algebratic equation etc. into three-dimensional finit volume algorithm to establish a three-dimensional efficient EM modeling method of the tool in an inhomogeneously anisotropic formation. Then the modeling results is applied to explore the characteristics of the tool in the complex reserviors, and the synthetic logs of the tool can be computed along arbitrary well arbitrary in complex formation. .After that, we will study method of well environment correction to reduce the effect of drill collar and borehole in order to extract the initial model parameters like as interfaces,relative dipping angles, horizontal and vertical condunctivities. According to shape of well logging curves, we divide the curves into a series of small windows, and use one dimansional parameterized inverse alogrithm to invert the logs in each window and reconstrunct the conductivities and interfaces of multi-bed in exess of 35m radial depth from well path. The inversion results in each windows are combined together to construct the resistivity image along the whole well trajactory. On the base, the three dimensional regularized iterative inverse alogrithm is set up to ellimate the effects of the invasion zone and borehole on the tool and to obtain true value of the horizontal and vertical condunctivities in some special beds.. Finally, the numerical tests about resistivity imaging and three dimensial inversion of the synthetic logs will be performed to analyze the post processing effects, and to improve all corresponding algorithms in order to establish theroretical base for development of the new type of the LWD EM tool.

随钻超深多分量电磁传播电阻率测井技术具有大的径向探测能力，是复杂储层评价、钻井优化、地质导向以及油藏精细描述的新型工具。首先，用优化Yee氏交错网格、电导率标准均匀化以及大型离散方程直接求解等技术改进三维有限体积数值模拟算法，研制非均质各向异性地层中随钻超深多分量电磁传播电阻率测井响应三维高效数值模拟技术，能够进行响应特征分析以及任意井轨迹上理论合成曲线的计算；然后，应用井眼环境校正技术降低钻铤、井眼等影响，提取层界面、相对视倾角以及地层纵横向电导率等模型参数，并根据测井曲线形态划分出一系列窗口，用一维全参数反演技术重建各窗口井轨迹35m径向范围内的地层电导率，将窗口反演结果组合起来、实现电阻率成像；在此基础上，用三维自适应正则化反演技术同时消除钻铤、井眼和侵入效应，确定特殊储层的纵横向电导率真值。最后，通过电阻率成像与三维反演数值试验，完善相关算法，为新型随钻测井技术的研制提供理论基础。

本项目围绕着随钻超深多分量电磁传播电阻率测井三维正反演算法与电阻率成像问题展开了如下几方面的研究：. 在正演计算方面.随钻多分量电磁传播电阻率测井仪器(MC-EPR)中发射与接收线圈是安装在钻铤内部环状刻槽中，并且环形刻槽中充填着高磁导率铁氧体，使得钻铤表面不再是光滑的柱面，针对钻铤表面非光滑的特殊结构，利用电场延拓技术逼近非光滑钻铤表面的完全电导率边界条件(PEC)，然后通过柱坐标系中的三维有限体积法(3D FV)，建立与非光滑钻铤表面完全协调的离散方程，借助直接法求解器Pardiso与稳定双共轭迭代算法(Bi-cgstab)提高三维数值模拟算法的稳定性与可靠性，且通过数值模拟结果研究考察了铁氧体磁导率变化、仪器偏心、层厚、泥浆电导率等变化，并对无钻铤、刻槽钻铤以及光滑钻铤三种不同钻铤的响应特征进行了定量对比分析，对消除钻铤影响、简化随钻测井资料处理进行了深入探讨。. 超深多分量远探测电阻率测井仪器(UD-MCEPR)的收发距变化范围为3米~40米，其探测范围比MC-EPR大得多，基于二次场技术与直角坐标系中三维有限体积法研制出三维非均质各向异性地层中数值模拟方法，有效地提高了电磁场计算精度以及三维正演效率，该算法能够进行多散射体、起伏边界、电导率各向异性、源距以及工作频率等情况下超深多分量远探测电阻率测井响应特征的模拟，为新型仪器源距设计与工作频率选取提供了有效手段。. 在三维反演成像方面. 根据MC-EPR的仪器结构研制出一套井眼校正库，应用井眼校正库与最小平方技术建立了直接应用MC-EPR资料提取视电导率、视各向异性系数以及视倾角等方法，并利用层状地层中的解析解与Frechet导数快速算法，研制出一维多参数反演方法，能够快速反演层状各向异性地层中各个地层电导率与层边界。.为实现超深多分量远探测电阻率测井资料成像，通过Green函数法研制出非均质各向异性地层中三维空间灵敏度快速算法，定量了考察源距与工作频率以及地层电导率变化等对仪器探测深度与空间分辨率的影响。在此基础上，利用摄动理论与三维有限体积算法研制出多尺度显式Fréchet导数高效算法，实现了三维参数化反演与多尺度三维像素反演中显式Fréchet导数的快速计算，为超深多分量远探测电阻率测井资料的三维成像提供了一种重要基础，最后建立了一套超深电阻率测井资料处理与解释的完整流程。

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