Impact of Fluid Distribution and Petrophysics on Geophysical Signatures of CO2 Storage Sandstone Reservoirs

• Published in: Journal of geophysical research. Solid earth 2024-05, Vol.129 (5), p.n/a
• Main Authors: Falcon‐Suarez, I. H., Mangriotis, M.‐D., Papageorgiou, G., Mondol, N. H.
• Format: Article
• Language: English
• Subjects: Aquifers; Auroras; Boreholes; Brines; Carbon capture and storage; Carbon dioxide; Carbon sequestration; Chemical interactions; Chemical reactions; Clay; Climate change; CO2 storage; Data logging; Earthquake damage; Elastic properties; Electrical properties; electrical resistivity; Flow simulation; Fluid flow; Fluids; Geophysical data; Geophysics; Global warming; Injection; Logging; Mitigation; Modelling; Monitoring; Offshore; Physics; Porosity; Remote sensing; reservoir heterogeneity; Reservoir storage; Reservoirs; Rocks; Sandstone; Sediment samples; Sedimentary rocks; Seismic activity; Seismic response; Seismic surveys; Shale; Storage capacity; Storage conditions; Surveys; ultrasonic waves; Water storage
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2024JB029027

Carbon Capture and Storage (CCS) is a key element to achieving net‐zero energy challenge timely. CCS operations require the integration of geophysical data, such as seismic and electromagnetic surveys, numerical reservoir models and fluid flow simulations. However, the 10–100s m resolution of seismic imaging methods complicates the mapping of smaller scale rock heterogeneities, while borehole measurements commonly show large fluctuations at sub‐cm scales. In this study, we combine laboratory data, well‐logging, rock physics theories and a proof‐of‐concept time‐lapse seismic modeling to assess the effect of pore‐scale fluid distribution and petrophysical heterogeneities on the expected performance of whole‐reservoir CCS operations in deep saline aquifers, by analogy to the Aurora CCS site, North Sea. We monitored the elastic and electrical properties of three sandstone samples with slightly different physical and petrographic properties during carbon dioxide (CO2) flow‐through tests under equivalent in situ effective pressure. We inferred the CO2‐induced damage in the rocks from the variations of their hydromechanical properties. We found that the clay fraction, CO2‐clay chemical interactions, and porosity were the main factors affecting both the CO2 distribution in the samples and the hydromechanical response. We used seismic modeling of well‐log data and the laboratory results to estimate the reservoir‐scale time‐lapse seismic response to CO2 injection and to assess the effect of the rock heterogeneities in our interpretation. The results show that disregarding the effect of rock heterogeneities on the CO2‐brine fluids distribution can lead to significant misinterpretations of seismic monitoring surveys during CCS operations in terms of both CO2 quantification and distribution. Plain Language Summary Excess of carbon dioxide (CO2) in the atmosphere is causing global warming. The most realistic long‐term and large‐scale mitigation technology is Carbon Capture (Utilization) and Storage (CC(U)S). The CO2 is captured from the main sources of emissions and injected into deep geological formation for its permanent disposal. Offshore saline aquifers formed by siliciclastic reservoir rocks (sandstones) appear as suitable emplacements due to large storage capacity, pore connectivity and low CO2‐fluid‐rock chemical reactivity. The main challenge for CCS is to ensure CO2 remains contained in the subsurface storage volume. Seismic and electromagnetic sources are the