Role of divalent ions, temperature, and crude oil during water injection into dolomitic carbonate oil reservoirs

Abstract

Although wettability alteration has been shown to be the main control mechanism of Low Salinity and Smart Water (LS-SmW) injection, our understanding of the phenomena resulting in wettability changes still remains incomplete. In this study, more attention is given to direct measurement of wettability through contact angle measurement at ambient and elevated temperatures (28 °C and 90 °C) during LS-SmW injection to identify trends in wettability alteration. Zeta potential measurement is utilized as an indirect technique for wettability assessment in rock/brine and oil/brine interfaces in order to validate the contact angle measurements. The results presented here bring a new understanding to the effect of temperature and different ions on the wettability state of dolomite particles during an enhanced oil recovery process. Our observations show that increasing temperature from 28 °C to 90 °C reduces the contact angle of oil droplets from 140 to 41 degrees when Seawater (SW) is injected. Besides, changing crude oil from crude-A (low asphaltene content) to crude-B (high asphaltene content) contributes to more negative surface charges at the oil/brine interface. The results suggest that the sulphate ion (SO42-) is the most effective ion for altering dolomite surface properties, leading to less oil wetness. Our study also shows that wettability alteration at ambient and elevated temperatures during LS-SmW injection can be explained by Electrical Double Layer (EDL) theory.

Optimization of salinity and composition of injected low salinity water into sandstone reservoirs with minimum scale deposition

“…The Zp of colloidal dispersions was measured using laser Doppler electrophoresis (LDE). In the LDE, a voltage across a cell is used, and the electrophoretic mobility of particles is obtained from the frequency shift observed in the scattered light 67,68 . The electrophoretic mobility measure is the best and simplest manner to estimate the Zp 69 .…”

“…The Zp values were the average of three measurements for the sample. Potential determining ions including Ca 2+ , Mg 2+ , and SO 4 2− can importantly influence the interactions at the LSW/rock interface that straight effects the EDL in oil reservoirs 68 . These ions are attached to the rock surface and change the rock-brine interface charge 86 .…”

“…2− ions at the rock surface, and the CaSO 4 − and MgSO 4 − complexes can create on the sandstone surface 68 . The negative surface charges on the OLSW/rock and OLSW/oil interfaces can yield electrostatic repulsion between the interfaces and donate to further positive disjoining pressure 88 .…”

Static and dynamic evaluation of formation damage due to barium sulfate scale during water injection in carbonate reservoirs

“…Recent studies indicate that the efficiency of water flooding operations is highly dependent on the salinity and composition of the injection water. In fact, oil/brine/rock interactions and the oil recovery can be optimized by modification of the injection water salinity and ionic composition (Sohal et al 2016;Fattahi Mehraban et al 2019;Mokhtari et al 2019;Rostami et al 2019).…”

Enhancing surfactant desorption through low salinity water post-flush during Enhanced Oil Recovery

“…Sheng reviewed that approximately 17 mechanisms pertaining to solely LSWF, among which fine migration, mineral dissolution, Multicomponent Ion Exchange (MIE), and wettability alteration stood as prominent [22]. Extensive works [23][24][25][26] presented comprehensive results regarding the effects of ion types on the effectiveness of LSWF. They found that SO 4 2À is the most dominant in driving rock to less oil wetness.…”