马头营干热岩开采试验场地人工注水诱发地震探讨

Study on Earthquakes Induced by Artificial Water Injectionin Matouying Dry Hot Rock Mining Test Site

结合马头营干热岩区7个临时测震台站的地震观测资料和M1井2022-06~09的加压注水数据,研究地震活动与注水压力、水流量的关系,同时分析诱发地震震源机制解及其对周边应力场的影响。结果表明,注水作业可能诱发了201个地震,震源深度主要集中在0~4 km,这个区段也是地围压较小的安全区域,发生中强震的几率较小;水流量、水压力的改变不仅影响诱发地震的时空分布特征,而且影响地震活动频度,应力积累到一定水平诱发地震发生,之后水流量、水压力与地震频度呈现正相关关系;注水量和震级之间关系不明显,压力和诱发地震震级呈线性相关;在持续注水量达到11 821 m^(3)、压力达到23.46 MPa时,有断层失稳、诱发地震的可能;最大诱发地震的震源机制解为走滑型,主压应力NNW向,与华北区域应力分布有一定偏差,可见M1井开采对局部应力分布有影响;从地震震中位置迁移规律推测,有新的地裂缝产生。

Based on the seismic observation data of 7 temporary seismic stations in the hot dry rock area of Matouying and the pressurized water injection data of M1 well from 2022-06 to 09,we study the relationship between seismic activity,water injection pressure and water flow;we further study the focal mechanism of induced earthquakes and analyze their influence on the surrounding stress field.The results show that 201 earthquakes may be induced by water injection operation,and the focal depth is mainly concentrated in 0-4 km.This area is also a safe area with small ground confining pressure,and the probability of moderate and strong earthquakes is small.The changes of water flow and water pressure not only affect the temporal and spatial distribution characteristics of induced earthquakes,but also affect the frequency of seismic activity.When the stress accumulates to a certain level to induce earthquakes,the water flow,water pressure and earthquake frequency show a positive correlation.The relationship between the amount of water injected and the earthquake magnitude is not obvious,and the pressure is linearly correlated with the induced earthquake magnitude.When the continuous water injection volume reaches 11821 m^(3) and the pressure reaches 23.46 MPa,the fault instability may induce earthquake.The focal mechanism of the maximum induced earthquake is strike-slip type,and the principal compressive stress is NNW,which has a certain deviation from the stress distribution in North China.It can be seen that the mining of M1 well has an effect on the local stress distribution.According to the migration rule of earthquake epicenter,there are new ground cracks.