Synthesis and performance evaluation of date pit based surfactant-polymer formulation for enhanced chemical flooding

Chemical flooding is one of the enhanced oil recovery (EOR) techniques that is used to prolong the lives of oil reservoirs. In this paper, the synthesis of date pit based polymers solution and its adaptability in surfactant - polymer flooding technique were investigated. Date seed from the eastern province of Saudi Arabia were washed by sonication and sun dried. The dried seeds were ground and de-oiled using hexane in a Soxhlet apparatus. The de-oiled powder was dissolved with aqueous sodium hydroxide solution to form date pit polymer (DPP) solution. The properties of the solutions were investigated by evaluating change in their rheological properties with temperature (40 - 110°C) and aging period. Also, the viscosity enhancement capability of DPP in the surfactant - polymer formulation was evaluated. The results obtained showed a saturated solubility range of 0.5 to 3.7 wt % of the solution, a yield between 23 and 69%, and viscosity range of 2.5 to 22cp at about 33°C. The optimum viscosity is about 22 times higher than the viscosity of the blank NaOH solution which is about 1.08cp at the same temperature. The viscosity modification property of the polymer was maintained up to a temperature of 80 °C. At 100 °C, the viscosity of the samples with 3.29wt% DPP dropped from 2.8 to 1.07cp which is about the same viscosity of that of the blank alkaline (NaOH) solution that was used as solvent. Thus, DPP can be utilized as viscosity modifier to alter the mobility ratio in enhanced oil recovery processes. However, more studies need to be done to find a better chemical modification route that can be used to improve the yield. Higher yield is expected to give polymer with higher viscosity. DPP application may be limited to light crude oil recovery and it can be used as blend with other high viscosity polymer to improve their performance. Accordingly, future work will be focused on detailed investigation of better chemical modification method. It is expected that this research will benefit the industry by serving as an eye opener into the possible exploration of the use of local raw materials for upstream operations in the oil and gas industries.