Unconventional oil recovery from Al Sultani tight rock formations using supercritical CO2

[Display omitted] •Solid phase with high porosity but low permeability.•Diffusion dominated extraction kinetics.•Decreasing IFT to 2 mN/m above 10 MPa.•Wettability alteration from water wet to non-water wet at elevated pressures.•Storage capacity of more than 3 wt% at moderate pressures. A systematic study was carried out on the governing mechanisms during extraction of hydrocarbons from tight rock formations using supercritical carbon dioxide at pressures between 15 and 40 MPa at 40 to 60 °C. Despite reasonable porosity, extraction kinetics are strongly diffusion controlled due to low permeability arising from small pore diameters and little pore interconnectivity. Other system properties were determined such as interfacial tension, contact angle, sorption and diffusivity, all related to the transport mechanisms inside the rock pores. The interfacial tension of hydrocarbons in CO2 decreases as a function of pressure yet maintains a fairly constant value between 15 and 40 MPa, which shows resemblance to heavy oil behavior. Concurrently the contact angle of formation water increases with pressure which helps mobilize and remove the aqueous phase. A feasible way of combining hydrocarbon extraction and CO2 sequestration in tight rock formations is shown at moderate pressure and temperature conditions.