TITLE:
Hydraulic Fracturing, Cumulative Development and Earthquakes in the Peace River Region of British Columbia, Canada
AUTHORS:
Allan R. Chapman
KEYWORDS:
Hydraulic Fracturing, Induced Earthquakes, Montney Trend
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.5,
May
26,
2021
ABSTRACT: Unconventional petroleum development involving large
volume fluid injection into horizontal well bores, referred to as hydraulic
fracturing (HF, or fracking), began in the Montney Trend of northeast British
Columbia, Canada, in 2005, quickly initiating earthquakes. Earthquake frequency
increased substantially in the Montney by 2008, in relation to the number of
wells fracked and the volume of injected frack water. A spatiotemporal filter
was used to associate earthquakes with HF wells. A total of 439 earthquakes (M 1.0 - 4.6 (NRCAN catalogue) during 2013-2019 have close association with HF
activity, of which 77% are associated with three operators. Fifteen percent of
HF wells in the Montney are associated with these earthquakes, while 1.7% of HF
wells are associated with M ≥ 3.0 earthquakes. There are strong linear
relationships between the maximum earthquake magnitude each year and the annual
volume of injected frack fluid. M ≥ 3.0 earthquakes are associated with
large cumulative frack water volumes for antecedent time periods of 1 - 3
years, often with fluid injection by multiple operators. Eighty-seven percent
of the Montney M ≥ 3.0 earthquakes have associated HF triggering events,
but a few are sufficiently distant to be ambiguous. Distances from the induced
earthquake epicentres indicate a variety of causal mechanisms are involved. It
is concluded that ~60% - 70% of M ≥ 3.0 earthquakes are induced by
hydraulic fracturing. HF-induced earthquakes can be considered in part related
to the cumulative development density from multiple proximal operators and
cumulative antecedent fluid injection over periods ranging from a few months to
a few years. It is probable that induced earthquakes of M > 5 will
occur in the future. There are significant public safety and infrastructure
risks associated with future HF-induced earthquakes in the Peace River area. To
carry out HF operations effectively and safely, potentially destructive
earthquakes must be avoided or mitigated. The Traffic Light Protocol mitigation
system used in British Columbia appears unlikely to prevent large magnitude
earthquakes. Risk avoidance therefore becomes important and could include the
establishment of frack-free zones proximal to populations and critical
infrastructure.