电极型复电阻率扫频系统响应数值模拟  

Numerical Modeling of Electrode-type System of Sweep-frequency Complex Resistivity

作　　者：尹成芳[1,2] 柯式镇[1,2] 张雷洁[1,2] 

机构地区：[1]中国石油大学,北京102249 [2]北京市地球探测与信息技术实验室,北京102249

出　　处：《测井技术》2014年第3期273-278,共6页Well Logging Technology

基　　金：国家"十二五"油气专项(2011ZX05020-009)

摘　　要：提出一种复电阻率扫频的电测井方法。该方法采用电极方式,在10Hz^500kHz频率范围内测量多个频率下的复电阻率。基于ANSYS平台,利用耦合电磁场方程开展了复电阻率扫频电测井响应的数值模拟。基于典型三层介质模型,频率采用100Hz,对比基于耦合电磁场方程与采用直接求解标量电位的拉普拉斯方程计算结果,两者最大误差不超过0.3%,证明模拟方法准确。经过合适的涡流影响校正,依据典型三层介质给出了平稳的界面响应,证明了油气的电频谱响应。不同工作模式探测深度表明,1~100kHz探测特性变化不大,最大探测深度可达1m。2个监督电极相位差随频率变化,但最大相位差不超过0.1°。不同情况下的模拟结果证明,在10Hz^500kHz宽频范围内,采用电极型复电阻率扫频的测井方法进行油气层识别可行;利用界面极化频率与含水饱和度的近线性关系特性识别油气,预示将突破传统单一电阻率或单一介电常数识别油气的方法。The sweep-frequency complex resistivity is proposed to be one kind of much effective tool for the hydrocarbon identification.With the electrodes as the probes,the modeling of complex resistivity under the coupling of magnetic and electric equations is based on ANSYS with the wideband from 10 Hz to 500 kHz.Comparing the result from the new algorithms（frequency spectra of typical three-layer model based on coupled equations）with the scalar potentials from the Laplace equation at 100 Hz,the maximum error is less than 0.3%.Both the spectra of the infinite homogeneous uniform medium after eddy current correction and simulated logs of typical three-layer model expose the useful information for hydrocarbon indication.The depth of investigation of the sonde shows the stability from 1kHz to 100 kHz,and is up to one meter.The phase difference of the monitor electrodes changes with the frequency,but the maximum is less than 0.1degree and can be ignorable which implies the feasibility of the tool.The modeling of different scenarios gives the confidence in hydrocarbon identification with the wide frequency range from 10 Hz to 500 kHz.Furthermore,the linear relationship between interfacial polarization frequency and water saturation would break the traditional approach of hydrocarbon identification with separate resistivity and permittivity.

关 键 词：电阻率测井 复电阻率 扫频 电极系 数值模拟 界面 极化 油气层识别 

分 类 号：P631.83[天文地球—地质矿产勘探]