微地震地面监测系统的优化设计

Design optimization of surface-based microseismic monitoring system for hydraulic fracturing

在水力压裂微地震定位中,监测系统的选取直接决定了定位的效果,并最终影响对压裂效果的评估。采用震源扫描算法对合成的地震信号进行定位以评估不同监测系统的定位效果。通过测试不同的检波器布设模式、布设范围以及布设间距对不同深度的微震事件的定位效果,得到了地面监测系统优化设计的一些基本原则:检波器数目基本相同时,星状系统优于网状系统;在一定范围内,适当增大检波器布设范围,增加接收线数,增大检波器间距,可以在节约成本的基础上得到较好的定位效果;监测系统布设范围的半径,应该与震源的深度相当,或略大于震源深度;若已知震源分布的大致范围,监测系统的检波器应该侧重于该范围布设等。

For microseismic monitoring of hydraulic fracturing,a monitoring system plays a very important role to the microseismic location accuracy.We have designed and tested a few surface-based microseismic monitoring systems,and evaluate them by processing synthetic seismic signals with the source scanning algorithm.These designs use different receiver arrays,receiver intervals,and coverage.The following understandings are obtained:(1)The star shape layout is better than the net shape layout when the number of receivers is equal;(2)Larger layout range,more receiver lines and larger receiver intervals may achieve better results and save the cost with a given number of receivers;(3)The layout radius of the monitoring system should be equal to or larger than the source depth;(4)If the source areas are known,more receiver lines should be above the source areas.