Robust NMR Examination of the Three-Phase Flow Dynamics of Carbon Geosequestration Combined with Enhanced Oil Recovery in Carbonate Formations

Abstract

A net-zero strategy for counterbalancing anthropogenic carbon dioxide (CO 2 ) emissions has become a key aspect in achieving the global decarbonization initiative by 2050. In particular, carbon geosequestration and enhanced oil recovery (EOR) in hydrocarbon reservoirs is a cost-effective strategy for attaining net-zero emissions. However, EOR and the ability to capture residual CO 2 are greatly affected by the presence or absence of oil layers along with the pore size distribution and fluid displacement, which drastically impact the reservoir-scale flow. Thus, the present study makes systematic use of the versatile in situ two-dimensional (2D) nuclear magnetic resonance (NMR) T 1 −T 2 imaging technique to visualize the fluid occupancy of the pore network in dolomite rock and uses the T 1 /T 2 ratios to assess the physicochemical properties thereof, including the microscopic wettability with respect to the pore-space fluids, after each process step. Specifically, the T 2 relaxation time is measured to demonstrate the displacement processes and to evaluate the trapping behavior and associated rock/fluid interactions at the pore level, which are closely correlated with the fluid flow behavior. Thus, in the tested water-wet dolomite, the strongest-wetting phase (i.e., water) is shown to occupy the smallest pores, where it is held by strong capillary forces, while the nonwetting CO 2 phase occupies the large pores and the intermediate-wetting oil reside in the intermediate-sized pores. As a result, 16% of the residual CO 2 trapped in large pores, while 71% of the oil is recovered, which is comparable to previous results obtained for analogue two-phase flow in water-wet dolomite samples, although some details differ and the displacements are noticeably complex. These findings have significant impacts on net-zero emissions, the budgets and storage capacities of CO 2 -EOR project schemes, and CO 2 geosequestration. In the latter context, the present findings also greatly increase the geo-storage integrity over reservoir-scale implementations.

Tailoring Water–Gas Ratios to Saturation Distribution for Improved Oil Recovery in Low-Permeability Reservoirs

“…We utilized the Peng–Robinson equation to model the phase behavior and property changes during the CO 2 flooding process. The relative permeability curves in this model were measured using the displacement apparatus depicted in Figure , assessing the interactions among oil, gas, and water under experimental conditions and calculated using the JBN method. − These curves were subsequently smoothed into two functions, as shown in Figure and Table . Additionally, grid properties, such as porosity and permeability, derived from the data distribution in Table , ensure that the model accurately simulates fluid dynamics under actual reservoir conditions.…”

Subsurface Hydrogen Storage in Limestone Rocks: Evaluation of Geochemical Reactions and Gas Generation Potential

“…Although utilizing a single type of limestone limits the generalizability of the findings to other carbonate formations, the experimental results can be applied to calcite-rich carbonate rocks or other rocks with similar petrophysical properties. It will be beneficial to address the impact of mineralogy and evaluate the reactivity of various carbonate rocks, i.e., dolomite rocks to hydrogen injection in future studies. , Third, the ICP results showed only minimal changes in ionic solutions when exposed to hydrogen, indicating minor dissolution of rock minerals in the water. However, in the long term, the dissolution and precipitation behaviors can cause ionization and lead to changes in brine chemistry.…”

Carbon Capture and Storage in Depleted Oil and Gas Reservoirs: The Viewpoint of Wellbore Injectivity

“…Technologies for CCS can increase the oil recovery through EOR/EGR up to 40%, whereas a recovery factor of 1-18% can be obtained after CO 2 injection in gas reservoirs [6,7,28,48,56]. A study using a Silurian core drilled from Door District in northeast Wisconsin, United States revealed an oil recovery of 34% during CO 2 flooding [57]. Studies conducted on gas reservoirs and CO 2 -EGR field pilots have revealed that common depleted gas reservoirs have CO 2 storage capacities of 390-750 gigatons [51,58].…”