New approaches to seismic monitoring at the Brooks Field Research Station
Donald C. Lawton, Malcolm B. Bertram, Kevin W. Hall, Kevin L. Bertram
The Containment and Monitoring Institute (CaMI) Field Research Station (FRS) is being developed by CMC Research Institutes, Inc. and the University of Calgary in Newell County, Alberta. The goal of this research station is to develop and calibrate various technologies for monitoring fluid injection and cap rock behaviour at depths of 300 m and 500 m below surface. The project has an emphasis on CO2 detection thresholds at these relatively shallow depths, but is also focussed on understanding and monitoring understanding shallow gas (CO2 and CH4) migration, particularly fugitive gas emissions. The specific objectives being assessed at the FRS are sensitivity of monitoring systems for early detection of loss of conformance and in mapping temporal changes in cap rock that may lead to loss of containment. The FRS is being constructed on lands southwest of Brooks, Alberta, and the 2.5 km2 site will operate for at least 10 years. Construction has begun on an array of wells, sensing stations, and surface facilities that will be monitoring fluid injection and cap rock behaviour. Seismic monitoring is advancing rapidly with time-lapse or 4D seismic surveys, but these are expensive and the time interval between repeated, conventional seismic surveys may temporally alias the geological changes taking place in the reservoir. There is now a move towards not only permanent receiver arrays, but also permanent seismic sources. These may operate continuously, or with a rapid repeat time which may enable trigger events to be detected in the subsurface. Some of these technologies include fibre optic distributed acoustic sensing (DAS) and fixed seismic sources. Plans are in place to install some of these systems at the FRS.