Wettability Alteration by Carbonated Brine Injection and Its Impact on Pore-Scale Multiphase Flow for Carbon Capture and Storage and Enhanced Oil Recovery in a Carbonate Reservoir

Abstract

Carbon capture and storage is key for sustainable economic growth. CO2-enhanced oil recovery (EOR) methods are efficient practices to reduce emissions while increasing oil production. Although it has been successfully implemented in carbonate reservoirs, its effect on wettability and multiphase flow is still a matter of research. This work investigates the wettability alteration by carbonated water injection (CWI) on a coquina carbonate rock analogue of a Pre-salt reservoir, and its consequences in the flow of oil. The rock was characterized by routine petrophysical analysis and nuclear magnetic resonance. Moreover, micro-computed tomography was used to reconstruct the pore volume, capturing the dominant flow structure. Furthermore, wettability was assessed by contact angle measurement (before and after CWI) at reservoir conditions. Finally, pore-scale simulations were performed using the pore network modelling technique. The results showed that CWI altered the wettability of the carbonate rock from neutral to water-wet. In addition, the simulated relative permeability curves presented a shift in the crossover and imbibition endpoint values, indicating an increased flow capacity of oil after CWI. These results suggest that the wettability alteration mechanism contributes to enhancing the production of oil by CWI in this system.

Driving Mechanisms in CO2-Assisted Oil Recovery from Organic-Rich Shales

“…Liu et al report that CO 2 solubility in aqueous solutions is in the following order: pure water > CaCl 2 brine > NaCl brine at similar temperature and pressure conditions, which would be expected to also reflect the swelling in the oil drop; however, no such trend can be verified according to our measurements. This is possibly due to the complicated partitioning of CO 2 within this complex four-phase system composed of an aqueous phase where carbonic acid is dissociated and molecular CO 2 is solubilized, an oleic phase where molecular CO 2 is also solubilized, and an organic pore system into which CO 2 is dissolved and strongly adsorbed …”

“…Wettability alteration has been extensively investigated in CO 2 –brine–rock systems for the purpose of carbon capture and storage (CCS). − As far as EOR is concerned, core flooding experiments are usually performed to verify the effect of CO 2 on increasing the oil recovery factor, − but these tests are limited to core samples from conventional reservoirs. The obtained data are related to the wetting behavior through the relative permeability . Contact angle (CA) data in brine–oil–rock systems with CO 2 dissolution are scarce in the literature for carbonate and sandstone reservoirs; even less work is found for unconventional formations such as shale.…”

“…The obtained data are related to the wetting behavior through the relative permeability. 29 Contact angle (CA) data in brine− oil−rock systems with CO 2 dissolution are scarce in the literature for carbonate and sandstone reservoirs; even less work is found for unconventional formations such as shale. Yang et al 30 investigated the effects of CO 2 on CA and volumetric changes of Weyburn crude oil on Weyburn limestone surrounded by reservoir brine under different pressures and temperatures.…”

Experimental determination of wetting behavior under non-atmospheric conditions relevant to reservoirs: a practical guide

“…Migration of hydrocarbons in porous media is also closely related to the interaction of the respective fluid phases with the rock surfaces under prevailing reservoir conditions [3]. Last but not least, efficiency of enhanced hydrocarbon recovery techniques depends on favorable relative permeabilities of the fluids present in oil and gas reservoirs that on their turn are influenced by the competitive wetting of aqueous and hydrocarbon phases on the inner pore surface; the phase showing the higher rock-fluid interactions has lower contact angles (higher wetting), thereby displaying less mobility [4] and lower relative permeability [5]. In all of the aforementioned applications, experimental determination of the wetting behavior in terms of the three-phase contact angle has become an essential approach in order to quantify the multiple interactions between all present phases under real conditions.…”

“…In analogy, the efficiency of methods of enhanced oil recovery (EOR) where gas is present also depends on the wetting behavior, but up to four phases (rock-brine-oil-gas) need to be considered depending on the recovery technique in question. To name a few: alternating gas-water flooding [14], carbonated water flooding [4],or a combination of these techniques, e.g. during foam flooding [15].…”