CO2 Sequestration projects are growing in number as the practicality of reducing harmful emissions into the atmosphere through carbon capture, utilization, and storage (CCUS) becomes a reality. Operators of sequestration facilities must contend with 3 issues:
- Confirming that the injected CO2 is staying within the target formation.
- Confirming the caprock integrity such that no gas escapes.
- Ensuring that the injection does not induce seismicity that is felt at the surface potentially doing damage to nearby infrastructure.
Conventional reflection seismic is usually shot over the candidate project area to locate faults and assess structural integrity of the injection site. But this is a static image that falls short of addressing the dynamic issues listed above.
Microseismic monitoring before and during injection is the proven technology for:
- Assessing the seismic hazard in the project area
- Mapping faults through the reservoir some of which may not have been detected by the reflection seismic
- Detecting movement of faults and fractures that could destroy caprock integrity
- Detecting small precursor seismic events to any larger induced seismicity
- Tracking the CO2 plume as it grows throughout the injection process
The cost effective vehicle for monitoring the project over it’s entire life is MSI’s BuriedArray®. Multicomponent geophones are cemented in to shallow (<300 ft.) boreholes at depths and intervals (~2000 X 2000 feet) that are custom designed for every project. Each station is equipped with telecommunication devices that collect the data and transmit them to a central processing facility for real time analysis. The recording and telecommunications equipment are powered by wind and solar and function autonomously except for maintenance visits on a semi-yearly basis. MSI has installed and operated 75 such arrays over the last 12 years for a variety of geotechnical purposes.
The array should be installed before injection begins to observe the baseline ambient seismic activity in the area. Once injection begins the continuous data stream can be analyzed to detect microseismic events that would indicate failure of the seal or the motion on regional faults that could lead to larger induced seismic events. A “stoplight system” can be established that automatically notifies the operator when events that surpass certain critical levels of magnitude, frequency or location are identified.
Critical to this monitoring are array design, array operational stability and real time analysis. With over 10 years of operating such facilities, MSI has the experience to exceed project requirements in each of these areas.
To learn more about CCS Monitoring, please contact MicroSeismic.