Investigation of crude oil properties impact on wettability alteration during low salinity water flooding using an improved geochemical model

Abstract

In low-salinity water flooding (LSWF), modifying the injected brine composition leads to greater oil recovery from carbonate reservoirs. The processes that control improved recovery during LSWF are not totally clear, which could lead to ambiguities in finding optimum brine composition regarding wettability alteration (WA) toward water wetness. One of the methods to determine WA is bound product sum (BPS) calculation using geochemical tools. In the case of wettability improvement, the BPS value of a crude oil-brine-rock (COBR) system should be at its minimum value. In this study, an improved geochemical model is developed, which includes the effects of oil composition (i.e., acid number, base number, and weight percent of nonhydrocarbon components) and physical properties of oil (i.e., density, viscosity, and solution gas-oil ratio) on COBR interactions. The proposed method generates BPS as a function of temperature, pressure, oil and brine composition, and pH for carbonate rocks. The model applicability was validated using several experimental data sets available in the literature. The results of the improved BPS model were in line with the results of contact angle and zeta potential measurements as the major indices of rock wettability. BPS calculations using the available geochemical tools sometimes failed to predict the correct WA trend since they overlooked the impact of oil properties on COBR interactions. The model predictability was also compared with the results of an available geochemical tool, PHREEQC, and the results demonstrate just how important the effect of oil properties and composition inclusion on wettability determination is. The improved BPS approach could be successfully utilized as an optimization tool to optimize the water composition during LSWF for a given COBR system.

Prediction of electrostatic properties of reservoir rock in low salinity water injection into carbonate reservoirs

“…In this regard, the tuning parameters in surface complexation of geochemical model are presented in Tables 6 , 7 , 8 for each of the surface sites. The reaction types are validated by Gorbani et al in 2022 35 . Since, the equilibrium constant (Ksp) of calcite is very higher than dolomite (Table 7 ).…”

Modelling of carbonate rock wettability based on surface charge and calcite dissolution

“…Some of the proposed models are based on the salinity of the brine [50], dissolution of the reservoir rock [9,10,35,51,52], and the concentration of adsorbed specific ion on the rock surface [41,53,54]. Others have used the amount of rock and oil surface species [8,55,56], concentration of adsorbed carboxylic oil component [6,57,58], ionic strength [59], concentration of aqueous ion [60], and migrated fines [61]. Some works have also applied the Deryaguin-Landau-Verwey-Overbeek theory (DLVO theory) to study the wettability alteration mechanism [62][63][64][65].…”

Surface Elemental Analysis of a Crude Oil-Modified Seawater–Carbonate Rock System

“…Improvement in wettability for dolomite rock and a negligible effect for calcite rock were observed when temperature increased. It is also stated that the degree of substitution of Mg 2+ with Ca 2+ from the chalk surface increased as the temperature increased . Mahani et al .…”

“…It is also stated that the degree of substitution of Mg 2+ with Ca 2+ from the chalk surface increased as the temperature increased. 23 Mahani et al 22 showed that the zeta potential of both rock/brine and oil/brine can reduce toward zero potential as a function of temperature that leads to the positive or negative effect of temperature on wettability alteration depending on the sign of zeta potential of oil/brine and rock/brine. The concentration of the active ions in seawater is much lower than the concentration of non-active ions, Na + and Cl − .…”