| 一种改进的基于网格搜索的微地震震源定位方法 |
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| 引用本文： | 谭玉阳,李罗兰,张鑫,何川.一种改进的基于网格搜索的微地震震源定位方法[J].地球物理学报,2017,60(1):293-304. |
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| 作者姓名： | 谭玉阳 李罗兰 张鑫 何川 |
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| 作者单位： | 1. 中国科学技术大学地球和空间科学学院, 合肥 230026;2. 北京大学地球与空间科学学院石油与天然气研究中心, 北京 100871;3. 中国石化石油勘探开发研究院, 北京 100083 |
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| 基金项目： | 中央财政拨款地质调查项目（DD20160217-3）资助. |
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| 摘 要： | 震源定位是微地震监测技术要解决的主要问题.目前,井下微地震监测多采用走时拟合法计算震源位置.常规方法受到环境噪声、初至拾取误差、速度模型误差等因素的影响,定位结果存在一定误差.为了提高定位精度,本文提出了一种改进的基于网格搜索的微地震震源定位方法.本文方法根据P波的偏振特征参数计算概率密度函数求取震源方位角,并采用改进的目标函数和搜索算法计算震源的径向距离和深度.模型数据和实际资料的处理结果表明,本文方法具有较强的抗噪性,计算得到的震源方位角更加接近真实值;与常规目标函数相比,本文方法采用的目标函数具有更好的收敛性,其定位结果受初至拾取误差和速度模型误差的影响更小;本文提出的搜索算法能够消除由于错误拾取造成的观测到时中的异常值对定位结果的影响.
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| 关 键 词： | 微地震 震源定位 偏振特征 目标函数 网格搜索 |
| 收稿时间： | 2016-05-02 |
An improved method for microseismic source location based on grid search |
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| TAN Yu-Yang,LI Luo-Lan,ZHANG Xin,HE Chuan.An improved method for microseismic source location based on grid search[J].Chinese Journal of Geophysics,2017,60(1):293-304. |
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| Authors: | TAN Yu-Yang LI Luo-Lan ZHANG Xin HE Chuan |
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| Institution: | 1. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China;2. Institute of Oil & Gas, School of Earth and Space Sciences, Peking University, Beijing 100871, China;3. Petroleum Exploration & Production Research Institute, SINOPEC, Beijing 100083, China |
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| Abstract: | Microseismic source location is the core problem for microseismic monitoring. As for the downhole monitoring cases, microseismic sources are normally located by minimizing the misfit between the observed and predicted travel times. Conventional method tends to be affected by many factors, such as ambient noises, arrival picking errors and velocity model errors, therefore produces results with larger discrepancies. We propose an improved method for microseismic source location. This method is based on grid search algorithm and some improvements are incorporated to enhance its location accuracy. The improvements include the use of a probability distribution function, which is calculated using the polarization attributes of P-wave, to estimate the source azimuth and the adoption of a new objective function and an improved search algorithm to find the optimal radial distance and depth of the source. The results from testing the proposed method on synthetic and real datasets have shown that this method has a strong noise resistibility and can produce more accurate estimate of the source azimuth. The new objective function shows better convergence than the traditional ones and its location results are less affected by the errors in the arrival times and velocity models. The improved search algorithm can mitigate the impact of erroneous picks on the location results. |
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| Keywords: | Microseismic Source location Polarization attribute Objective function Grid search |
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