油气藏MT激电效应一维正演研究  

1D forward simulation of MT induced polarization (IP) effect of reservoir.

作　　者：岳安平[1] 底青云[1] 王妙月[1] 石昆法[1] 

机构地区：[1]中国科学院地质与地球物理研究所

出　　处：《石油地球物理勘探》2009年第3期364-370,共7页Oil Geophysical Prospecting

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-YW-121)资助

摘　　要：模型实验表明,在大功率人工固定源极低频电磁频率测深的频率范围内,Dias模型适用于0.1～300Hz频率和1～10km深度范围油气藏激电参数提取的要求。考虑油气藏激电参数后,视电阻率、视电阻率比值BρT和视相位、视相位比值BφT曲线存在明显异常,具体表现为:①BρT异常峰值均小于1,表明在大功率人工源极低频电磁波测深范围内,均能将介质扩散电流阻抗和极化阻抗部分分离,并可"识别"出纯直流电阻率;②电阻率断面类型对响应曲线有显著影响,并在油层位于三个深度层次(浅层、中间层、底层)时呈现一致规律:对于全部频段而言,BρT及BφT峰值对应频率递减顺序为A型、O型、Q型、K型、H型,其中A型、O型、Q型峰值频率较高,K型、H型峰值频率接近并较小;③比值异常峰值及其对应频率与含油气极化层厚度有明确的正相关关系,可通过此性质判断极化层厚度,比值异常峰值与含油气极化层埋深有明显的对应关系,可以通过异常峰值大小判断极化层埋深,但对应频率与深度对应关系不明显,不利于进行判断。The model experiments showed that the Dias model is suitable for the requirement of IP parameters abstraction of reservoir within the 0.1~300Hz frequency and 1~10km depth ranges in the sounding frequency range of extra-low electromagnetic frequency with larger-power manually-fixed source. Considered the IP parameters of reservoir, there exist obvious abnormalities among the curves of apparent resistivity, apparent resistivity ratio BρT, apparent phase and apparent phase ratio BφT, which showed as follows: ①all BρT abnormal peaks are less than 1, showing that partial separation of proliferated current impedance from polarization impedance of medium and 'recognition' of pure DC impedance can be implemented in the sounding frequency range of extra-low electromagnetic frequency with larger-power manually-fixed source; ②there is significant influence of fault-surface type of resistivity on response curves and consistent rule appears in three different depth levels of reservoir (shallow, mid and bottom), for all frequency segments, the frequency descending orders relative to BρT and BφT peaks are A,O,Q, K and H type respectively, among which the peak frequencies in A, O and Q types are higher and the peak frequencies in K and H types are similar to each other and smaller; ③there is clear positive correlation between abnormal peaks of ratios, their relative frequencies and thickness of oil/gas-bearing polarization bed, which can be used for judging the thickness of polarization bed, and there is correspondent relationship between abnormal peaks of ratios and buried depth of oil/gas-bearing polarization bed, which can be used for judging the buried depth of polarization bed, but it is no easy to judge because there is no clear correspondent relationship between them.

关 键 词：大功率人工固定源 极低频电磁测深 激电效应Dias模型 模型正演 比值曲线异常 

分 类 号：P631.325[天文地球—地质矿产勘探] P618.130.2[天文地球—地质学]