Migration Patterns of Injection- and Postinjection-Induced Seismicity: Applications to Local and Regional Scales [thesis]

Lisa Johann, Universitätsbibliothek Der FU Berlin
In many cases, fluid injections into the subsurface have been recognised to cause seismic activity. Understanding the driving physical processes of these man-made earthquakes and their occurrence in time and space is of significant scientific and public interest. Not only does a deeper insight into the physics of fluid-induced seismicity yield fundamental knowledge on seismogenic processes in the brittle Earth's crust but it is also a crucial point for reservoir characterisation and injection
more » ... rformance. In the end, these are inevitable steps towards seismic hazard assessment and risk mitigation. The focus of this thesis is on spatio-temporal migration patterns of fluid-induced seismicity at different scales. In a first study, I work with seismicity induced by the rather local effect of single-borehole, high-pressure fluid injections. This part is followed by two studies on earthquakes caused by the regional impact of large-volume injections through numerous wells under gravity. Whereas high-pressure, single-borehole injections are typically used for hydraulic fracturing operations to enhance shale gas recovery from unconventional reservoirs and for hydraulic stimulations of geothermal heat production sites, gravity-driven, large-volume injections are part of wastewater disposal which has been performed throughout the last decade in the central U.S. In the context of this work, wastewater is a saline fluid, co-produced with natural oil and gas, which is re-injected into the subsurface at a later stage. Apart from the actual injection phase, I also consider seismic events that occur in the postinjection interval of high-pressure fluid injections and in times of decreasing wastewater disposal volumes. I assess the governing question which parameters and physical processes control features of fluid-induced seismicity in time and space by joining different methods. By means of analytical solutions, I derive a novel scaling law for postinjection-induced seismicity in the first study. My findings suggest that the spat [...]
doi:10.17169/refubium-28833 fatcat:2dmoojgra5am5l7xfgbausvlz4