Dynamic Processes of CO2Storage in the Field: 1. Multiscale and Multipath Channeling of CO2Flow in the Hierarchical Fluvial Reservoir at Cranfield, Mississippi

Abstract

AbstractA consistent picture of dynamic channeling, invasion, spreading, and breakthrough (CISB) of supercritical CO2 in the hierarchical fluvial reservoir at Cranfield, Mississippi is presented after 10 years of integration and analysis of complementary field monitoring and characterization data. The dynamic CISB with small‐scale CO2‐flow channels in the F1‐F2‐F3 cross section (F1, F2, and F3 are one injection and two monitoring wells) was imaged by daily electrical resistance tomography (ERT) and time‐lapse crosswell seismic surveys. One, three, and four CO2 flow channels logged at F1, F2, and F3, respectively, were dynamically connected with strong temporal variations in CO2 saturation during 221 days of drainage with injection rate doubling twice and 81 days of imbibition. Three intermediate‐scale CO2 flow channels (with highest CO2 saturation) normal to the cross section were ERT‐imaged during late‐time drainage. A large‐scale, sinuous fluvial CO2 flow channel was imaged by repeat surface seismic survey at the end of the imbibition. The fluvial sandstone channel sinuously bypasses the F1‐F2‐F3 cross section in a point bar, but the channel is connected to the cross section through an intermediate‐scale sandstone channel, forming a complicated flow channel network. The multiscale flow channel network (in the fluvial channel‐point bar system) revealed from the observed CISB enables us to consistently interpret the hydrological monitoring data of three tracer tests, each conducted during an injection rate step, and preinjection hydraulic‐thermal‐tracer tests. This interpretation of the CISB and flow channel network can guide future modeling and data inversion to best understand the effects of natural heterogeneity on CO2 storage efficiency and residual trapping.