Sensitivity Analysis of Geomechanical Constraints in CO2 Storage to Screen Potential Sites in Deep Saline Aquifers

Abstract

In order to tackle the exponential rise in global CO2 emissions, the Intergovernmental Panel on Climate Change (IPCC) proposed a carbon budget of 2,900 Gt to limit the rise in global temperature levels to 2°C above the pre-industrial level. Apart from curbing our emissions, carbon sequestration can play a significant role in meeting these ambitious goals. More than 500 Gt of CO2 will need to be stored underground by the end of this century to make a meaningful impact. Global capacity for CO2 storage far exceeds this requirement, the majority of which resides in unexplored deep aquifers. To identify potential storage sites and quantify their storage capacities, prospective aquifers or reservoirs need to be screened based on properties that affect the retention of CO2 in porous rocks. Apart from the total volume of a reservoir, the storage potential is largely constrained by an increase in pore pressure during the early years of injection and by migration of the CO2 plume in the long term. The reservoir properties affect both the pressure buildup and the plume front below the caprock. However, not many studies have quantified these effects. The current analysis computes the effect of rock properties (porosity, permeability, permeability anisotropy, pore compressibility, and formation water salinity) and injection rate on both these parameters by simulating CO2 injection at the bottom of a 2D mesh grid with hydrostatic boundary conditions. The study found that the most significant property in the sensitivity analysis was permeability. Porosity too affected the CO2 plume migration substantially, with higher porosities considerably delaying horizontal and vertical migration. Injection rate impacted both the pressure rise and plume migration consistently. Thus, in screening potential storage sites, we can infer that permeability is the dominant criterion when the pore pressure is closer to the minimum principal stress in the rocks, due to which injection rate needs to be managed with greater caution. Porosity is more significant when the lateral extents of the reservoir limit the storage potential.

Minireview on CO2 Storage in Deep Saline Aquifers: Methods, Opportunities, Challenges, and Perspectives

“…21 The pressure buildup phenomenon occurs in deep saline aquifers by the continuous injection of Sc-CO 2 into the reservoir due to poro-mechanical effects. 44 The poromechanical effect describes how the increment of fluid pressure within the pore space of the aquifers is influenced by its mechanical properties such as porosity, permeability, viscosity, and confining pressure. 45 During Sc-CO 2 injection into aquifers, injected CO 2 occupies the pore spaces by compressing the rock matrix and displacing the existing brine which in turn increases pressure within the aquifer.…”

“…Thermal, chemical, buoyancy, and poro-mechanical effects are responsible for the change of stress–strain field . The pressure buildup phenomenon occurs in deep saline aquifers by the continuous injection of Sc-CO 2 into the reservoir due to poro-mechanical effects . The poro-mechanical effect describes how the increment of fluid pressure within the pore space of the aquifers is influenced by its mechanical properties such as porosity, permeability, viscosity, and confining pressure .…”

Data-Driven Quantitative Study of Synergistic Effects on CCUS-EOR─A Case Study of Ultralow-Permeability Sandstone Reservoirs

“…Recently, many researchers have found key parameters impacting the geological storage efficacy of conventional CCUS-EOR systems. These parameters include reservoir permeability, porosity, thickness, depth, initial reservoir pressure, oil density, injection pressure, reservoir capacity, production pressure, and in situ oil–water volume. − The majority of current research, however, has concentrated on comprehending the mechanisms through which CO 2 improves the recovery of crude oil, frequently using generic homogeneous models and ignoring reservoir heterogeneity and the influence of CO 2 –water–rock geochemical reactions on CO 2 -EOR and storage. The reservoir heterogeneity has a direct impact on the injected fluid efficiency, which in turn affects development results.…”

Effect of equilibrium contact angle on water equilibrium film thickness for the carbon dioxide–brine–mineral system based on surface force theory

“…Geological storage of anthropogenic carbon dioxide is expected to isolate large quantities of the gas compared to other sequestration options due to the promising global storage potential (Verma et al 2021). However, while the storage potential is attractive, water-rock interaction phenomenon that controls wettability, and the distribution of sub-surface fluid phases (brine and dioxide) is less understood.…”

“…Different types of saline aquifers occur in nature, but those of sandstone origin provide the greatest global storage capacity (William et al 2016) with promising global distribution and favorable compressibility (Verma et al 2021). Similar to Badera et al (2014).…”