Porosity Alteration of Carbonates by CO₂-Enriched Brine Injection

Abstract

Carbon dioxide (CO2) is considered one of the main gases that cause global warming. In this perspective, its injection in aquifers and oil and gas reservoirs has been a possible alternative to reduce its emission in the atmosphere. An alternative strategy in which CO2 is used efficiently in the Oil Industry is the Carbonated Water Injection (CWI), where the carbon dioxide is injected through the reservoir dissolved in the brine, eliminating problems of gravitational segregation and low sweeping efficiency present in other gas injection methods. Once injected, the fluid may react with the carbonate rock and inducing their dissolution, causing changes in the petrophysical properties of the rock. This work investigated changes in the average porosity of carbonate samples from Brazilian reservoir through a dynamic flow test with enriched brine with 100% CO2 injection under high pressure and high temperature conditions and simulating a region around the face of the injector well, with an injection pressure of 8,500 psi, a temperature of 70 °C and a flow rate of 2cm3/min. The core-flooding experimental setup includes two coreholders arranged in series with samples confined in its interior, which are swept by X-ray Computed Tomography (CT), taking measurements of average porosity data. The results showed that there was dissolution in the sample assembled in the first coreholder since the porosity had increased, while in the second, no significant alterations of the porosity were observed (around 8.5% of its initial value). This observation can still be confirmed by the analysis of the dissolved moles, which exhibit behavior similar to the porosity, indicating that some minerals actually suffered dissolution from the injection of carbonated brine.

Study of empirical correlation between permeability and porosity with application for permeability upscaling

“…From these results, it is possible to observe that values for the upscale model are very similar to those found for the reference refined model. The presence of numeric dispersion is still detectable in these cases, but in smaller levels than 16 Oil production rates for the 1D models that for 1D. Also, it is possible to conclude that the correlation proposed by Eq.…”

“…Computed tomography (CT) and micro-computed tomography (micro-CT) have been used to access internal structure in porous media since the 1980s [13,14]. Some fluids can change porous media petrophysics, mainly due to mineral dissolution and precipitation [15,16].…”

Investigation of Water Composition on Formation Damage and Related Energy Recovery from Geothermal Reservoirs: Geochemical and Geomechanics Insights

“…Generally, ff the injected water contains sulfate ions in high concentration, it can react with calcium, barium, ferric, and strontium ions present in the formation water. The inorganic scales could precipitate and deposit, as soon as the state of supersaturation is attained [17][18][19]. Table 1 displays different scales and their deposition types in porous media [20].…”