An experimental approach to investigate oil recovery during ion-tuned water injection: A new insight into the asphaltene effect

Abstract

Regarding the increase of the worldwide demand for supplying fuel, Enhanced Oil Recovery (EOR) methods, as promising methods for increasing oil recover factor, is a vital issue. The smart water injection is a well-accepted as an environmentally friendly, inexpensive, and efficient EOR method. This research aims to investigate the effect of oil and asphaltene chemistry on the sensitivity of oil production toward ion-tuned water. In this regard, three oil samples of crude oil, deasphaltened oil, and asphaltene-rich toluene were employed, as well as various brine samples containing different salinity values and ion types. The provided oil samples were characterized using Fourier-transform infrared spectroscopy (FTIR) and elemental analysis. The interfacial tension (IFT) values between the prepared water and oil samples of crude oil, deasphaltened oil, and asphaltene-rich toluene was in the ranges of 7.5–11, 14–23, and 12–19 m.N/m, respectively. Regarding higher IFT between the sulfate-rich water and asphaltene-rich oil, it was shown that the asphaltene molecules have a lower affinity toward the sulfate ions. In contrast, enriching the seawater with magnesium and calcium ions led to a tense IFT reduction. Regarding the contact angle measurements, the wettability of the sections, which were aged by the asphaltene-rich toluene, was respectively less sensitive to the ion-tuned waters compared with those aged by deasphaltened oil. For instance, because of the seawater treatment, the contact angles of the sections lie in the ranges of 48–87, 45–83, and 56–98° for sections aged by crude oil, deasphaltened oil, and asphaltene-rich toluene, respectively. More feasibility of the calcium and magnesium for desorption of the hydrocarbons was also observed in the zeta potential tests. The overall effects of rock-fluid and fluid-fluid interactions were observed in the imbibition tests. While the production from the crude oil saturated due to imbibition of the magnesium and calcium was noticeable, lower production was observed due to the sulfate-rich water imbibition into the asphaltenic oil sample. The experimental approach in this study could be a benchmark to screen the suitable reservoir oil for water injection.