Investigating stress transfer via fluids in a hydraulic fracturing environment using seismic, geodetic, and hydrological observations coupled with poroelastic modeling techniques

点击翻译按钮获取中文摘要

There are few ways to constrain stress transfer via fluid migration in fault zones when studying natural earthquakes. However, studying induced earthquakes provides a valuable opportunity to try and answer the above question, because the added anthropogenic contribution to stress loading or unloading in injection and extraction environments can be constrained more easily than natural tectonic fault loading. Seismicity has increased drastically in the Western Canadian Sedimentary Basin since 2011, when unconventional energy production activity increased drastically. The overarching aim of this study will be to use a dense array of seismic stations, high resolution InSAR and GPS observations, well pressure and geochemical analyses, and modeling approaches to link input stresses in the form of injection and flowback fluid pressures and rates to a relationship for earthquake occurrence to constrain stress transfer in the crust. We will focus on a site near Dawson Creek, British Columbia, Canada where seismic response to pumping is vigorous, including a ML 4.5 induced earthquake related to hydraulic fracture stimulation of a nearby well that occurred on the 30th of November, 2018. In order to work toward establishing a magnitude-predictable relationship between operational parameters and earthquake production, we will:• Use both ambient noise/seismic tomography, as well as shear wave splitting techniques to detect changes in fault structure surrounding the ML 4.5 induced earthquake and aftershock sequence, as well as the remainder of a 36-month study period • Create an enhanced earthquake catalog and source parameter estimates to link the spatial/temporal evolution of earthquakes to evolving damage and fluid movement• Investigate the source parameter scaling relationships of induced earthquakes and the influence of time-dependent velocity changes on estimated values• Investigate the time dependence of 3D velocity structure to investigate correlations with earthquake source properties and injection activity• Investigate elastic properties of crustal rocks using high-resolution geodetic observations and responses to groundwater fluctuations and injected fluids, as well as the correlation between seismic activity and longer-term ground deformation• Use seismic and geodetic observations to test and constrain hydrogeological and poroelastic models; use models to predict the injection conditions under which earthquakes will nucleate• Investigate relationships through changes in groundwater chemistry and seismicity, including potentially remotely triggered earthquakesThe planned project duration totals 36 months, and requested funds include support for one PhD student, one student assistant, conference travel for the PhD student, and installation costs to augment the preliminary network of seismic stations currently in place at the study site with five additional seismometers, as well as three GPS/GNSS receivers.