Sustaining heavy crude oil production with chemical EOR: A comparative study

The proposed work aims to conduct a comparative study regarding the feasibility of chemical EOR in producing heavy crude oil with respect to part of a porous medium in the upper Assam basin, India. The current study incorporated two crude oil samples, CSG1 and CSG2, belonging to the upper Assam oil field, having an °API of around 23° and 19° and viscosities of 25.785 mPa.s. at 64.94 °C and 42.9 mPa.s. at 40 °C, respectively. In the current work, alkaline (A) solutions were first synthesized with different concentrations of sodium carbonate (Na 2 CO 3 ) with 0.5 % weight in volume (w/v) of sodium hydroxide (NaOH) and measured for surface tension (ST), interfacial tension (IFT), and contact angle (CA). The subsequent analysis included the formulation of alkaline surfactant (AS) solutions. Na 2 CO 3 and NaOH were used to prepare the alkaline solution in distilled water (DW), while sodium lauryl sulfate (SLS) was used to prepare the surfactant solutions. The AS solutions were then analyzed for estimation of ST, IFT, and CA by varying the % (w/v) concentration of SLS while maintaining the composition of the alkaline part at 0.5 % (w/v) Na 2 CO 3 with 0.5 % (w/v) NaOH. This followed the formulation of alkaline surfactant polymer (ASP) solutions. For that, alkaline and surfactant components remained the same, but for polymers, this study used Xanthan gum with different concentrations. The current study used the drop shape analyser method for the determination of ST, IFT, and CA (for wettability). Based on the interaction of crude oil with differently concentrated A, AS, and ASP solutions and with the porous media, the findings on the feasibility of heavy crude oil recovery were analyzed. The current work finally concludes that AS solutions are more effective in enhancing heavy oil recovery than alkaline and ASP flooding, as they are capable of lowering the IFT and CA more than alkaline and ASP flooding.