全频段电测井正演数值模拟理论研究

4
全频段电测井正演数值模拟理论研究
摘要
ABSTRACT
Being an important method in well logging, the electrical logging is widely used in oil fields. The electrical logging commonly includes D.C.( direct current) logging and A.C.( alternating current) logging, and the former is usually used in conductive-mud boreholes and mainly reflects formation resistivity; The latter can be used in almost all kinds of boreholes and its responses are related to the formation electrical parameters(resistivity, dielectric constant and permeability). Therefore, the study of forward modeling of Electrical logging is of high value and significance. In this paper, the numerical mode-matching method(NMM) of A.C. logging is introduced in detail; the radial basis functions are discussed; with the help of the corresponding forward programs developed, the responses of some formation models are computed; the response curves of R-signal and X-signal of induction log as well as amplitude ratio and phase shift of the radio-frequency logging are analyzed. The main conclusions are as follows: NMM is an efficient forward method for axially symmetric formations; the investigation depth of X-signal is greater than that of R-signal; the vertical resolution of R-signal is better than that of X-signal; magnetic formations could cause significant perturbations on X-signal; borehole’s effect on amplitude ratio and phase shift can usually be ignored; the vertical resolution and radial investigation depth of the amplitude ratio and the phase shift do not match each other; for the conventional electric logging tools, the error caused by the approximation that the transmitter coil is treated as the point magnetic dipole can be ignored. In addition, in view of the similarity of NMM between D.C. logging and A.C. logging, NMM of the normal resistivity logging is introduced; a dissent is put forward about previous work; the corresponding forward program is also developed, and the responses of some formation models are computed. Key words: Forward method, Numerical Mode-Matching method(NMM), Basis functions, R-signal(Resistive signal) and X-signal (Reactive signal), Amplitude ratio and Phase shift
全频段电测井正演数值模拟理论研究
摘要
摘
要
电法测井在测井行业中占有重要地位，目前广泛应 用于油田生产。普通电阻率测井及侧向测井只能在井内 有导电泥浆时才能使用，其响应主要反映地层电导率。 交 流 电 测 井 可 以 应 用 于 各 种 井 眼 情 况 ,利 用 的 是 交 流 电 的互感原理，使得发射线圈通过交流电时，接收线圈感 应出与地层参数有关的电动势。高频交流电测井响应既 反映地层电导率，又反映地层介电常数。 首先，本文详细地介绍了交流电测井数值模式匹配 法原理，讨论了径向基函数，开发了相应的正演程序， 计算了一些地层模型的响应。针对感应测井的 R 信号与 X 信号响应曲线以及射频段介电测井的幅度比与相位差 的响应曲线进行了分析，得出的主要结论有：数值模式 匹配法对于轴对称地层是一种效率很高的正演方法；X 信号的探测深度大于 R 信号的探测深度；R 信号的分层 能力好于 X 信号的分层能力；X 信号对磁性地层的响应 比 R 信 号 敏 感 得 多 ；一般情况下，可不予考虑井眼对幅度比 与相位差的影响； 幅度比与相位差曲线在分层能力和探测深度 上不匹配；对于常规仪器，在理论分析时，可以忽略把发射线 圈当成磁偶极子引起得误差。 其次，考虑到数值模式匹配法原理的相通性，本文 还介绍了普通电阻率测井的数值模式匹配法原理，对前 人的工作提出了异议，并编制了相应的正演程序，给出 了几种地层模型的响应结果， 并与解析结果进行了比较。 关键词：正演，数值模式匹配法，基函数，R 信号与 X 信号，幅度比与相位差
2.关于幅度比与相位差的结论及建议 ............................................................... 81 3.关于 NMM 法正演的结论与建议 ................................................................... 82 参考文献 ....................................................................................................................... 83
全频段电测井正演数值模Байду номын сангаас 理论研究
2010-2-10
摘 要 ...................................................................................................................... 4 第一章 综 述 ............................................................................................................. 6 §1.1 电法测井的发展概况 ................................................................................... 6 §1.2 电法测井的正演方法 ................................................................................... 8 §1.3 本论文的主要工作 ....................................................................................... 9 第二章 交流电测井数值模式匹配法原理 ............................................................... 10 §2.1 用 NMM 法求多层不均匀介质中的波 ......................................................... 10 §2.2 反射阵和透射阵 ......................................................................................... 13 §2.3 源 项 ........................................................................................................... 15 §2.4 解题步骤 ..................................................................................................... 16 §2.5 径向上的基函数 ......................................................................................... 16 §2.5.1 常用