As a means of delaying climate change, injecting carbon
dioxide
(CO2) into geological structures can be an effective carbon
capture, utilization, and storage (CCUS) strategy. All geological
structures are naturally spatial heterogeneity, which can significantly
affect fluid flow and heat transfer, thereby affecting CO2 storage. We modeled fluid flow and heat transfer in 12 CO2 storage scenarios with spatially heterogeneous reservoirs using
a thermal-hydraulic-mechanical (THM) coupled model of a 3D wellbore-reservoir
system. CO2 injectability and distribution uniformity were
studied in relation to reservoir vertical heterogeneity and interlayers.
The optimization method of engineering parameters is discussed. Positive
rhythm reservoirs exhibit more uniform CO2 distribution
laterally under gravity than reverse rhythm reservoirs. In high permeability
ratio reservoirs, the low-temperature zone has a longer transfer distance
and CO2 is more likely to be injected, but channeling is
prone to occur. Reservoir porosity has little effect on reservoir
CO2 injectability and temperature distribution. The interlayers
will weaken the influence of gravity and reduce the CO2 injectability while providing additional storage volume. Injecting
CO2 at a lower temperature and mass flow will increase
injectability. The uniform distribution of CO2 laterals
is most effectively improved by hydraulic fracturing. Using low thermal
conductivity materials for the wellbore insulation to reduce heat
replenishment from the surrounding formation is critical.