利用微地震记录互相关成像的震源定位方法

基于微地震记录偏移叠加的微震定位方法是通过对振幅叠加来提高微震信号的信噪比,无须拾取微震初至;但其叠加成像效果易受初至极性反转的影响,对噪声的压制效果也不甚理想。文中利用不同检波器记录的同震源波形相似的特点,提出一种基于微震记录互相关成像的震源定位方法。即将时差校正后的微震记录之间的互相关系数相乘,构造成像函数,计算地下所有网格的成像能量值,通过能量极大值的网格点实现震源定位。针对模拟数据和实际资料的测试结果均表明,该方法能较好地同时压制噪声和初至极性反转对震源成像的干扰,提高了震源成像分辨率和定位精度。

Source location through microseismic cross-correlation imaging

Microseismic events may be located through migration and stacking,which improves the signal to noise ratio; it is unnecessary to pick arrival time.But such stacking may be affected by the polarity reversal of first arrivals,and noises cannot be efficiently suppressed.In view of similar waveforms from a same source recorded at different geophones,we propose a method of source location through microseismic cross-correlation imaging.An imaging function is formulated by multiplying cross-correlation coefficients of microseismograms after moveout correction,and then imaging energy at all nodes is calculated.The microseismic source is finally located using the maximum energy.Model and field data tests show that noises and the impact of first-arrival polarity reversal on source imaging could be reduced,which results in improved resolution and location accuracy of source imaging.