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加拿大西部大部分由注水活动引起的地震,据推断是水压致裂引起的;但美国中西部,大量盐水处理则是主要触发因素。基于模板的地震目录(目录来自一个地震活跃的加拿大页岩区)与4个月区间的详尽注水数据,表明地震在时间和空间上都紧密地集中于水压致裂点附近。最大事件(矩震级MW3.9)发生在注水的几周后,位于一条似乎从注水区延伸到结晶基底的断层上。地震活动的模式表明,作业期间的应力变化可使断层活化,滑动的偏移距离>1km,而水压致裂使断层增压会产生持续数月的幕式地震活动。
Most of the earthquakes caused by waterflooding activities in western Canada were presumably caused by hydraulic fracturing; however, extensive salt water treatment was the main trigger in the central and western United States. The detailed waterflooding data for the template-based seismic catalog (from a seismic-active Canadian shale area) and the 4-month interval indicate that earthquakes are tightly and temporally spatially concentrated near the point of hydraulic fracturing. The largest event (moment magnitude MW3.9) occurred a few weeks after the water injection on a fault that seemed to extend from the water flooding zone to the crystalline basement. The patterns of seismic activity indicate that the stress changes during operation can activate the fault with slip distance> 1km, and hydrofracturing causes the fault-plenum to produce a curtain-type seismic event lasting several months.