2024 PESA WEBINAR SERIES: Deploying Passive/Microseismic Technology to Monitor Subsurface Reservoirs During CO2 Injection

TenzorGEO aim to advance passive seismic CO2 monitoring technology to enhance environmental stewardship in carbon capture and storage, and together with operator partners ADNOC have deployed the technology in the Middle East. The results showcase the ability of passive seismic data to verify the containment of CO2 and serve as an early warning system and stability indicator for injected CO2. The solution known as Cuttlefish Carbon Guard (CCG) integrates both passive seismic and microseismic methods with a wider frequency spectrum from 0 – >100Hz to locate microseismic events, analyse the integrity of the caprock and the storage reservoir, and analyse spectral responses due to CO2 saturation velocity changes to visualise the reservoir and injected CO2.

Method:

To develop and standardise acquisition, processing and interpretation of microseismic data acquired during CO₂ monitoring projects the following areas was focused on: Data acquisition, method workflow, software and algorithm testing as well as development.

Data Acquisition: Here, an effective combination of sensor types 1C and 3C were designed and deployed as patches in a grid array. This helped achieve an integrated workflow with reduced volume of acquired data and improved SNR. Data acquired is in the frequency range of 0.1 – >100Hz with tests performed onsite prior to acquisition to determine and suppress surface waves.

Method Workflow: Integrate and adapt two standalone passive seismic methods into one solution capable of analysing, filtering, processing and interpreting data to visualise the storage reservoir and injected CO₂.

Method A aims to locate the microseismic events and determine the moment tensor in the reservoir rock – i.e. in response to changes in pressure, fluid displacement, pore fluid saturation, reactivation of fractures and filtration channels.
Additionally, Method B analyses the spectral response of vertically directed P-waves from ambient background microseismic noise (0.1 – 10 Hz) to delineate CO₂ saturated rock due to velocity changes.

Software: Finally, test the capability of the software by acquiring relevant passive seismic data from a CO₂ injection project in a field trial with ADNOC. The data acquired will feed into the model and educate the interpretation team as they aim to standardise procedure and application of the solution.

Conclusions:

The field project highlights the capability of an integrated passive/microseismic solution, paving the way for standardized procedures in the measurement, monitoring and verification (MMV) sector of the industry. The project underscores the technology’s potential to add cost, security and innovative value while monitoring subsurface reservoir integrity and track CO2 velocity changes. The continuous monitoring nature of the technology can help to increase public and stakeholder confidence.