Exploring date palm ash for greener enhanced oil recovery: Experimental and simulation studies on thermophysical properties and recovery performance

Sustainable oil recovery has become imperative due to environmental and economic concerns. It has also necessitated exploration of plant-based injectants for enhanced chemical oil recovery (CEOR). Date palm ash (DPA) is a waste product from combustion of palm fibers and shells. In this research, injection of DPA solution for CEOR has been proposed due to its high alkalinity. For this purpose, a series of studies including experimental determination of physico-chemical properties as well as thermodynamic modeling and simulation of thermophysical properties have been employed to characterize DPA solutions. Subsequently, numerical modeling and simulation of EOR performance considering DPA-polymer injection was conducted as proof of concept. Experimental results show that DPA contains different elements including Ca, K, Mg, Al, Na, P, S, Cl, and Si, as well as transition metals such as Mn, Fe, Cu, and Zn, typical of wood biomass ash. In addition, an alkaline medium (pH: 10 - 13) was obtained from 0.1 - 10 % wt/wt. DPA solution. The thermodynamic simulation and analysis show that the hypothetical DPA solution is characterized by the presence of basic cations (Ca²⁺, K⁺, Mg²⁺, and Na⁺), hydroxides (CaOH⁺ and MgOH⁺), and carbonates (CO₃^2- and HCO₃^-). Furthermore, pertinent thermophysical properties including osmotic pressure (39.04 - 4469.8 kPa), ionic strength (0.0148 - 1.194 mol/kgw), heat capacity (75.21 - 157.21 kJ/kgmole), and conductivity (1.42 - 125.21 mS/cm) were calculated for the solution. Similarly, the viscosity, density, and molecular weight of the DPA solution (0.1 - 10 % wt/wt.) were found to range between 0.891 to 1.047 cP, 0.9998 to 1.08 g/cm³, and 18.03 to 19.6 g/mol, respectively. Ultimately, the EOR simulation showed that DPA solution could be applied for alkaline assisted polymer flooding to mitigate polymer adsorption and improve oil recovery with overall performance similar to those observed using synthetic caustic (NaOH) injection.