| 横向各向同性地层中倾斜线圈系响应特征的数值模拟 |
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| 引用本文： | 张雷,陈浩,王秀明.横向各向同性地层中倾斜线圈系响应特征的数值模拟[J].地球物理学报,2012,55(10):3493-3505. |
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| 作者姓名： | 张雷 陈浩 王秀明 |
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| 作者单位： | 声场声信息国家重点实验室 中国科学院声学研究所, 北京 100190 |
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| 基金项目： | 国家自然科学基金，2010年中国科学院研究生科技创新与社会实践资助专项资助 |
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| 摘 要： | 详细推导了模拟倾斜线圈系在横向各向同性地层中响应的垂向数值模式匹配方法,在轴对称模型下,该方法采用垂直本征模式描述三维激励源,使得三维问题可以在二维条件下快速解决,另外,本文引入的高阶基函数进一步提高了算法的计算速度.为了验证算法的可靠性与准确性,分别与均匀无限厚各向同性地层的解析解和横向各向同性地层的有限差分解进行对比,结果表明,模式匹配方法与它们吻合的较好.在此基础上,利用模式匹配方法模拟了倾斜线圈系和水平线圈系在横向各向同性地层的响应特征,计算结果表明:在横向各向同性地层中,倾斜线圈系的响应既受水平电导率的影响,也受垂直电导率的影响,而水平线圈系则只与水平电导率有关,由此,可以通过倾斜线圈系评价地层的各向异性特征.此外,本文还分析了钻铤对倾斜线圈系响应的影响,模拟结果表明,虽然钻铤没有改变相位值和幅度值的变化趋势,但对它们的绝对值有一定的影响,而且这种影响与不同法向角度也有关系,因此当组合不同倾斜线圈系进行地层评价时,需要对钻铤的影响进行校正.最后研究了不同法向角度线圈系在横向各向同性地层中的响应特征,得出不同法向角度线圈系的探测特性和对各向异性的敏感性都有较大的差异.本文的研究表明倾斜线圈系的响应与水平线圈系的响应不同,通过利用不同倾斜线圈系组合可以进行油气储层评价.
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| 关 键 词： | 倾斜线圈系 数值模式匹配法 横向各向同性介质 |
| 收稿时间： | 2011-10-12 |
Numerical modeling of responses to a tilted-coil antenna in a transversely isotropic formation |
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| ZHANG Lei
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CHEN Hao
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WANG Xiu-Ming.Numerical modeling of responses to a tilted-coil antenna in a transversely isotropic formation[J].Chinese Journal of Geophysics,2012,55(10):3493-3505. |
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| Authors: | ZHANG Lei CHEN Hao WANG Xiu-Ming |
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| Institution: | State Key Laboratory of Acoustics Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China |
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| Abstract: | We put forward a modified Numerical Mode-Matching (NMM) method in detail which is used to simulate the responses of tilted-coil antenna arrays (TCAs) in a Transversely Isotropic (TI) formation, and the vertical eigenmodes are used to model the titled loop antenna sources for convenience. Moreover, the amplitude and slope basis functions are introduced into the simulation to speed up the calculation effectively. First of all, in order to validate the reliability and accuracy, the modeling results in a simple formation model by NMM are compared with those in the 3-D simulation of the analytic approach, also the modeling results in a complex formation of NMM are compared with those by a Finite Difference Time Domain (FDTD) method. They are both in a good agreement with each other. Based on this verification, TCAs and horizontal coil antenna in a transversely isotropic formation are studied, and it is shown from the computation results that TCAs are sensitive to the vertical resistivity and the horizontal resistivity together in TI formations but horizontal coil antenna are only sensitive to the horizontal resistivity. Therefore TCAs are very useful for evaluating a Transversely Isotropic formation. And then, the effects of the metallic mandrel on the responses are discussed, it is found that although the metallic mandrel does not change the trend of the phase and the amplitude change, it does influence the absolute value of the two signals and the effect is related to the normal directions. So we concluded that the effect of the metallic mandrel should not be neglected when TCAs are used to evaluate the formation. Finally, we discuss the effect of the different normal directions on the responses of TCAs, it shows that TCAs with different normal directions have different response characters due to the formation. In conclusion, TCAs have different responses as compared with the horizontal coil antenna, and we could use the various combinations of TCAs to evaluate the formation. |
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| Keywords: | Titled-Coil antenna arrays Numerical mode-matching Transversely isotropic media |
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