The Relationship Between Seismicity and the Oil and Gas Industry in Western Alberta and Eastern B.C.
Monday, 14 December 2015: 09:30
305 (Moscone South)
Significantly increased production of hydrocarbons in North America is being driven by the development of unconventional resources whose commercial viability, in many cases, depends upon massive subsurface injection of fluids. Although relatively uncommon, elevated pore pressure from fluid injection of any kind can induce earthquake activity by activating slip on a proximal fault. In the western Canada sedimentary basin (which follows the Rocky Mountain foothills region and straddles the border between Alberta and B.C.), we find that hydraulic fracture treatment, wherein fluids are injected under high pressure in long laterally-drilled wells in order to induce localized fracturing of a rock formation, is the primary triggering mechanism of induced seismicity. This contrasts with the central U.S., where most induced seismicity has been attributed to large-scale wastewater injection into deep disposal wells. Our findings are based on a comprehensive statistical analysis of seismicity at the M≥3 level since 1985, along with a complete well database for the region, containing information on many thousands of oil and gas wells. Since 2010, most of the regional earthquakes of M≥3 are correlated in both time and space with hydraulic fracturing. Monte Carlo simulations confirm that the observed correlations are extremely unlikely (<<1%) to have been obtained by chance. Improved understanding of regional variability in fault activation processes, accounting for operational and geological factors, will aid in the development and validation of predictive models for the time-dependent hazards from induced earthquakes.