| 摘要: |
| 基于水平层状地层的Green函数得到仅利用磁场幅度信息进行井间电导率一维反演的方法,基于轴对称二维地层模型的积分方程得到仅利用磁场幅度信息进行井间电导率二维成像的方法,并通过算例分析上述方法的可行性及精确性。结果表明,仅利用磁场的幅度信息对井间电磁场进行一维反演时,只要信息量足够、数据误差较小,仍能较准确地获得井间高阻层和低阻层的一维分布。仅利用总磁场的幅度信息在发射—接收剖面对井间电磁场进行二维成像时,影响成像质量的主要因素是井间异常体分布的复杂程度;在信息量数目远大于未知量数目、测量数据误差较小的前提下,对于异常体分布简单的地层,仅利用总磁场的幅度仍可以获得可接受的成像结果;异常体在井间的分布越复杂,成像效果越差。仅利用总磁场的幅度信息对井间电磁场进行联合反演成像时,只要信息量足够,分别进行一维反演和二维成像仍可获得地层电导率在发射—接收剖面的分布。 |
| 关键词: 井间电磁场 幅度 一维反演 轴对称二维模型 成像 |
| DOI：10.3969/j.issn.1673-5005.2021.01.006 |
| 分类号::P 631.9 |
| 文献标识码:A |
| 基金项目: |
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| Method and feasibility of cross-hole electromagnetic inversion and imaging by only using magnetic field 's amplitude information |
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WEI Baojun1, GU Jingwen1, REN Chen1, DANG Feng2, LIU Jian1
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(1.College of Science in China University of Petroleum (East China), Qingdao 266580, China;2.China Petroleum Logging Company Limited, Xi 'an 710077, China)
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| Abstract: |
| The 1-D cross-hole conductivity inversion algorithm by magnetic field 's amplitude-only information was obtained on the basis of Green 's functions in horizontally layered formation. The 2-D cross-hole conductivity imaging algorithm with amplitude-only information was obtained on the basis of integral equations for axial symmetric 2-D formation model. The feasibility and precision of the algorithm were analyzed by numerical examples. The results showed that when 1-D cross-hole electromagnetic inversion is conducted by only using magnetic field 's amplitude, the 1-D distribution of high-resistivity and low-resistivity layers between the holes can still be precisely obtained so long as the amount of information is large and the error of the measured data is small. When 2-D imaging is conducted on the transmitter-receiver section by only the amplitude, the imaging quality is mainly influenced by the complexity of the abnormal body 's distribution between the holes. For the formation with simply distributed abnormal bodies, an acceptable imaging result can still be obtained by only using amplitude only so long as the number of information is much bigger than the number of unknowns and the error of the measured data is small enough. The 2-D imaging results become less reliable with increasing complexity of the abnormal body 's distribution. When a joint inversion is conducted by using only the total magnetic field 's amplitude, the formation 's conductivity distribution on the transmitter-receiver section can still be obtained by conducting the 1-D inversion and 2-D imaging in turn, so long as the amount of information is large enough. |
| Key words: cross-hole electromagnetic fields amplitude 1-dimensional inversion axial symmetric 2-dimension model imaging |
