Experimental study of the effect of carbonated brine on wettability and oil displacement for EOR application in the Brazilian Pre-Salt reservoirs

Abstract

Brazilian Pre-Salt carbonate reservoirs are natural candidates for Enhanced Oil Recovery combined with Carbon Capture and Storage due to their high CO 2 production. However, the effect of CO 2 on rock wettability still needs to be investigated to build representative reservoir models to predict the ultimate oil recovery. This work applied contact angle measurements to study the consequences of carbonated brine on the initial wettability. Moreover, coreflooding experiments were carried out to evaluate the incremental oil recovery obtained by carbonated brine injection. Finally, nonreactive tracer tests and micro computed tomography were used to observe the effects of mineral dissolution on the sweeping efficiency. Carbonated brine induced a decreased oil-wet behavior caused by rock dissolution and desorption of organic compounds resulting in a contact angle reduction of 55°for the Pre-Salt rock. This contributed to obtain a 27% increase in oil recovery. Moreover, tracer tests and micro computed tomography verified the formation of preferential flow paths by mineral dissolution. The increased oil production and decreased contact angle encourage further studies on the injection of carbonated brine for the Pre-Salt scenario.

Effects of carbonated water injection on the pore system of a carbonate rock (coquina)

“…A review of worldwide CO2 flooding field projects indicates incremental recoveries ranging from 5 to 20% of the original oil in place (OOIP) (Sheng, 2013). Viscosity reductions and oil swelling are the main effects that enhance oil recovery, with wettability alterations and mineral dissolution also contributing to oil displacement (Drexler et al, 2019). CO2 injection can cause dramatic changes in the fluid-fluid and rock-fluid interactions, such as reductions in the pH, reducing oil viscosity and enhanced rock dissolution.…”

“…For example, Nowrouzi et al (2020) and Seyyedi et al (2020) observed higher porosity and permeability values after injection. However, Drexler et al (2019) noted a reduction in weight, porosity, pore volume and permeability of the sample after injecting carbonated water (desulphated seawater saturated with CO2), while Abbaszadeh et al (2016) reported a reduction in porosity and the sample's weight, but an increase in the permeability. By contrast, Wang et al (2019) observed almost no changes in the porosity but a significantly lower permeability.…”

“…Most studies noted the importance of rock dissolution as such, and the transport and deposition of fine particles (e.g., Jia, 2019;Mahzari et al, 2019). Grigg and Svec (2003), Drexler et al (2019) and Mahzari et al (2019) showed microCT images of a carbonate rock sample after injection of a brine rich in CO2. While these studies observed localized calcite dissolution at the inlet of the sample, they did not explain the occurred phenomena at the pore scale.…”

Experimental Research on the Law of Energy Conversion during CO2 Sequestration in Coal

“…With the increasing consumption of fossil fuel energy, CO 2 emissions continue to rise, which poses a serious threat to the global climatic and ecological environment [1][2][3]. The carbon capture and storage (CCS) technology has become an internationally recognized and critical emission reduction strategy [4][5][6].…”

Correlations between TDS and electrical conductivity for high-salinity formation brines characteristic of South Atlantic pre-salt basins

“…Additionally, basins in offshore Angola, Gabon, Cameroon, Democratic Republic of Congo, Equatorial Guinea and Namibia have been proposed as analogous prospects to the Brazilian Pre-Salt with outstanding potential for hydrocarbon reserves (Koch et al, 2013;Jameson et al, 2011). The formation brines in fields from South Atlantic pre-salt reservoirs can have TDS values over 150 000 mg/L (Drexler et al, 2019(Drexler et al, , 2020. Given the economic relevance of these reservoirs, it is important to study an adequate and efficient method for measuring the TDS of their brines, which are outside the range of the correlations present in the literature.…”