Temporal variation of the shallow subsurface at the Aquistore CO₂ storage site associated with environmental influences using a continuous and controlled seismic source

Abstract

The development of reliable systems for monitoring injected CO2 is essential in carbon capture and storage projects. We applied time‐lapse surface wave analysis to measure temporal variations of the shallow subsurface among 11 periods (0.2–21.6 days) of continuous seismic data acquired from 2014 to 2016 at the Aquistore CO2 storage site in Canada. We focused on monitoring environmental influences on shallow seismic velocity, which are unrelated to CO2 injection into deep reservoirs. A continuous, controlled seismic source system called Accurately Controlled Routinely Operated Signal System was used to enhance the temporal resolution and source repeatability. Observed phase velocities were clearly higher in winter than in warmer seasons. The seasonal variation could be reproduced by an increase in the shallow S wave velocity during winter associated with the greater extent of freezing of partially saturated rock. We also observed gradual increases or decreases in phase velocities as the seasons changed, which could be related to gradual freezing or melting of ice. Our monitoring system thus could be effective for monitoring temporal variations of the shallow subsurface associated with the degree of freezing. Furthermore, the high temporal stability of our monitoring approach in warm seasons may make it possible to immediately identify CO2 leakage in the shallow subsurface.

Seismic monitoring of a small CO2 injection using a multi-well DAS array: Operations and initial results of Stage 3 of the CO2CRC Otway project

“…A linear electromagnetic vibrator on the surface was trialled at Ketzin (Arts et al, 2013). A large eccentric vibrator was deployed at the Aquistore site (Nakatsukasa et al, 2016); however, seasonal near-surface variations precluded the use of the data to monitor the injection (Ikeda et al, 2017). Dual-motor permanent eccentric sources were tested at the CaMI project (Andersen, 2019;Spackman, 2019).…”

Estimating picking errors in near‐surface seismic data to enable their time‐lapse interpretation of hydrosystems

“…,b; Ikeda e t al . 2017), water level changes (Lu ; Pasquet et al . , ), permafrost thaw (Ajo‐Franklin et al .…”

“…Time-lapse approaches for seismics have been recently used for a wide range of applications and at different scales to track changes of seismic signal and mechanical properties associated with climatic variabilities (Bergamo et al 2016a,b;Ikeda et al 2017), water level changes (Lu 2014;Pasquet et al 2015bPasquet et al , 2016a, permafrost thaw (Ajo-Franklin et al 2017) or deep fluid storage (Arts et al 2004;Chadwick et al 2010). In the meantime, passive seismics have also been developed and recently proved to be efficient in the continuous auscultation of subsurface layers at the 0.01% level (Lecocq et al 2017).…”

River Corridor Model Constrained by Time‐Lapse Seismic Acquisition

“…Time‐lapse seismic methods have been developed to track temporal changes of Earth's near‐surface properties, for instance, linked to weathering effects (Bergamo et al., 2016a; Bergamo & Socco, 2016; Ikeda et al., 2017; Lu, 2014), water level variations (Lu & Likos, 2004; Pasquet, Bodet, et al., 2016; Pasquet, Bodet, Longuevergne, et al., 2015), permafrost thaw (Ajo‐Franklin et al., 2017) or deep fluid storage (Arts et al., 2004; Chadwick et al., 2010). Seismic techniques recently became part of the hydrogeophysics' toolbox to study not only the CZ architecture (St. Clair et al., 2015) but also its water content (Cameron & Knapp, 2009; Grelle & Guadagno, 2009; Konstantaki et al., 2013; Pasquet, Bodet, Dhemaied, et al., 2015; Pasquet, Bodet, Longuevergne, et al., 2015; Pasquet, Holbrook, et al., 2016; Pride, 2005).…”