Publication Date:
2024-02-29
Description:
Potential CO2 leakage from deep geologic reservoirs requires evaluation on a site-specific
basis to assess risk and arrange mitigation strategies. In this study, a heterogeneous and realistic
numerical model was developed to investigate CO2 migration pathways and uprising time in a
shaly overburden, located in the Malaysian off-shore. Fluid flow and reactive transport simulations
were performed by TOUGHREACT to evaluate the: (1) seepage through the caprock; (2) CO2-rich
brine leakage through a fault connecting the reservoir with seabed. The effect of several factors,
which may contribute to CO2 migration, including different rock types and permeability, Fickian and
Knudsen diffusion and CO2 adsorption in the shales were investigated. Obtained results show that
permeability mainly ruled CO2 uprising velocity and pathways. CO2 migrates upward by buoyancy
without any important lateral leakages due to poor-connection of permeable layers and comparable
values of vertical and horizontal permeability. Diffusive flux and the Knudsen flow are negligible
with respect to the Darcy regime, despite the presence of shales. Main geochemical reactions deal with
carbonate and pyrite weathering which easily reach saturation due to low permeability and allowing
for re-precipitation as secondary phases. CO2 adsorption on shales together with dissolved CO2
constituted the main trapping mechanisms, although the former represents likely an overestimation
due to estimated thermodynamic parameters. Developed models for both scenarios are validated
by the good agreement with the pressure profiles recorded in the exploration wells and the seismic
data along a fault (the F05 fault), suggesting that they can accurately reproduce the main processes
occurring in the system.
Description:
Published
Description:
1016
Description:
OSA5: Energia e georisorse
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
