ESG is pleased to announce the launch of EnviroMap™, a fully integrated monitoring solution designed to address containment and environmental compliance issues associated with CO₂ sequestration, waste injection and natural gas storage projects.

Carbon Capture and Sequestration (CCS) is being rapidly adopted on a global scale, as an effort to combat carbon emissions and mitigate climate change. Measurement, Monitoring, and Verification (MMV) is a critical component to the success of any sequestration or storage project. With the increased implementation of CCS projects, the demand for effective MMV techniques is also increasing.  EnviroMap™, ESG’s newest monitoring system, is specifically designed to target risk detection in order to minimize the human and environmental impacts of geological sequestration and storage projects. 

Microseismic Technology

Microseismic monitoring is not a new technology in the energy industry, where its primary application has been the imaging and interpretation of hydraulic fracture treatments used to stimulate unconventional gas reservoirs.  Microseismics is also used in real-time reservoir monitoring by deploying downhole sensor arrays designed to ‘listen’ to the reservoir’s response to stimulation and production activities.  With this technology, operators can obtain real-time information on the changing conditions of the reservoir and optimize their operations based on this feedback.  One of the principle advantages of microseismic monitoring is that it is among the only technologies on the market that will allow operators to obtain a continuous stream of information on the dynamic processes occurring away from the wellbore. 

The EnviroMap™ system is a turnkey integration of microseismic instrumentation, software and processing services.  EnviroMap™ uses custom designed and manufactured downhole geophone arrays that are deployed down monitoring wells located in near proximity to the principle injectors.  Equipped with temperature and pressure sensors, the retrievable arrays are connected to ESG’s Paladin™ Seismic Recorder.  Microseismic events associated with the injection are identified and recorded, and are then transmitted to ESG’s geophysical team for processing and analysis.  Event locations are mapped in x, y, z + time coordinates, and are displayed in an interactive visual format.  This processing can also be conducted in real-time at the injection site, providing operators with immediate feedback on the injection behavior. 

Minimizing Environmental and Human Impact

EnviroMap™ is designed to reduce the operational and environmental risk associated with sequestration and storage projects.  Operators can use the system to verify caprock/seal integrity, ensuring that the injection does not breach the caprock and seep to the surface or escape into adjacent water-bearing formations.  Microseismic monitoring will also reveal the reactivation of any naturally occurring faults or fracture networks within the reservoir which may influence the injection or create potential leakage pathways.  Real-time surveillance and automatic alarming programs can be implemented to allow operators to react immediately to any potential injection related risk. The EnviroMap™ system can also be used to correlate microseismic activity with engineering/injection parameters in order to assist with the optimization of injection pressures while ensuring that fracture pressures are not exceeded.

ESG’s record of successfully deploying EnviroMap™ systems includes a temporary installation designed to monitor a CCS field test for a geologic sequestration program in the Midwest USA.  During this test, roughly 10,000 tones of CO₂ were injected over 31 days.  Two temporary downhole eight-level triaxial geophone arrays were deployed in individual monitoring wells located within 2500 feet of the injection well.  The arrays were configured with an overall aperture of 345 feet, and provided detectability for events of moment magnitude ~-3 and greater originating within the target volume. 

Data was continuously recorded and analyzed throughout the deployment period.  During a period of high relative injection rate, a microseismic event located below the base of the caprock was detected on both arrays.  Seismic Moment Tensor Inversion analysis was performed, revealing a complex failure mechanism that is consistent with a crack opening or fracture initiation.  Although further analysis suggested that the caprock was not compromised, the event location and characteristics reinforced the hypothesis that higher injection pressures may have influenced the formation.  Incorporating such information into operating practices can assist in determining optimal injection rates and provide operators with direct feedback on injection compliance.

EnviroMap™ can also be applied to monitoring underground natural gas storage, where gas is held in inventory underground and under pressure, generally in depleted oil reservoirs, aquifers or salt caverns.  In these scenarios, EnviroMap™ systems are deployed to verify storage integrity and to help account for any variance or discrepancies.  Similarly, EnviroMap™ is used in the USA and in the Far East to satisfy regulatory compliance issues related to waste sequestration programs.

Fig. 1: During the design phase, ESG will conduct a feasibility study to determine which system configuration will optimize event detection and location accuracy.