Initial Results of Time-Lapse Processing of VSP Geophone and DAS Fiber-Optic Cable at Aquistore CO2 Injection Site, Sask

Summary The Aquistore CO2 storage site is located near the town of Estevan, Saskatchewan, Canada. The CO2 reservoir is located at a depth of about 3300 m, and injection and observation wells are drilled down to that depth. A coal-fired power plant east of the wells supplies the CO2 and a pipeline transfers the CO2 to the injection well. Prior to injection, vertical seismic profiles (VSPs) were acquired in November 2013 with two receiver types: a 60-level geophone tool deployed at a depth range of 1650–2650 m, and a fiber-optic cable used for distributed acoustic sensing (DAS) installed from the surface to a depth of 2766 m. CO2 injection started in April 2015 with a planned injection rate of 500–600 ton/day. In February 2016 about 36 kilotonnes of CO2 was injected when the first monitor VSP geophone and DAS data were acquired. The second DAS monitor survey was acquired in November 2016 when about 102 kilotonnes of CO2 was injected. We have applied a similar processing flow to all vintages of both geophone and DAS data to evaluate how repeatable VSPs can image the CO2 plume.