Experimental investigation of water composition and salinity effect on the oil recovery in carbonate reservoirs

Abstract

Water injection has been known as a conventional approach employed for years in order to achieve higher oil recovery from oil reservoirs. Since the last decade many researchers conducted on the water injection assessment suggested that low salinity water flooding can be an effective flooding mechanism and it can be used as an enhanced oil recovery method. Several examinations were conducted to identify governing mechanisms entailed in oil extraction and the effect of salinity and different types of ionic contents contained in Formation Water (FW) and injected fluid. This study is dedicated to address the influence of salinity and different types of ionic contents contained in formation water and injected fluid on incremental oil recovery. For this purpose, fluid–fluid and rock–fluid interaction were investigated especially for evaluating the effect of calcium ions in the formation water and sulfate ions in the injected water. Several experiments were carried out including core-flooding, contact angle, and imbibition tests. While former researchers concluded that reducing the salinity of injected water causing a decrease in ionic strength may lead to a greater oil recovery, in this research, we showed that these statements are not necessarily true. It was observed that existence of the high calcium concentration in the formation water would cause significant effect on wettability status of rocks and final oil recovery during low salinity water injection. This process is mainly due to rock wettability alteration. Wettability alteration mechanism in carbonate rocks is explained through interaction between rock and fluid composition. The results indicate the decisive role of calcium ions in the formation water at all stages from aging in oil to primary and secondary recovery. In addition to that, it was observed that more sulfate ion concentration in the injected water enhances rock wettability alteration.

Experimental study of the low salinity water injection process in the presence of scale inhibitor and various nanoparticles

“…As a result of this sedimentation, the permeability of these pathways is reduced, and the brine is directed to the intact pathways, resulting in increased sweep efficiency and ultimate oil recovery (Abhishek et al 2018;Chen et al 2021;Mahboubi Fouladi et al 2021;Mardashov et al 2021). Zaheri et al (2020) reported that the type and concentration of the ions in the brine play a vital role in the wettability changes and the ultimate oil recovery. Based on the experimental study, Su et al (2018) observed that the maximum change in wettability is observed at the optimal salt concentrations.…”

Optimization of ionic concentrations in engineered water injection in carbonate reservoir through ANN and FGA

“…Thus, the Wettability Alteration (WA) to more water-wet conditions is a crucial parameter to decrease the residual oil saturation (Hirasaki et al, 2004;Saikia et al, 2018;Seethepalli et al, 2004;Webb et al, 2004). Zaheri et al (2020) perform coreflooding analysis with carbonates using LSWI. They observed a relation between higher calcium content in formation water and a more oil-wet condition.…”

Application of ion-engineered Persian Gulf seawater in EOR: effects of different ions on interfacial tension, contact angle, zeta potential, and oil recovery

“…In another study, Lashkarbolooki et al (2017) found that NaCl and KCl exhibit different behavior in changing wettability, such that contact angle decreases by increasing KCl concentration or reducing NaCl concentration. Moreover, Zaheri et al (2020) reported that the concentration of CaCl 2 in formation water (FW) can play an important role in wettability alteration.…”