A natural polymer extracted from Chia seeds for application in chemical enhanced oil recovery by taper polymer concentration (TPC) and alkali-polymer (AP) slug injection into sandstone oil reservoirs

Abstract

In this research, the extracted mucilage from Chia seeds is introduced as a new natural polymer for use in polymer injection into oil reservoirs. Chia seeds polymer (CSP) is environmentally friendly, economical, efficient and available, and its industrial production and extraction are done in the world for use in various applications. Polymer fluid injection was performed under two polymer injection scenarios: taper polymer concentration (TPC) and alkali-polymer (AP) slug injection. CSP is stable up to salinity above 90,000 ppm and also maintains its performance at reservoir temperature. The viscosity changes of CSP solutions against shear rate confirm its non-Newtonian behavior, which increases in intensity with increasing CSP concentration. The CSP hydrocolloid increases the viscosity of the injection fluid at low concentrations to suitable values for EOR. In this way, the viscosity values of polymer solutions at concentrations of 200, 400, 600, 800, 1000 and 1200 ppm were equal to 27.14, 42.36, 68.11, 93.75, 125.62 and 154.51 mPa.s, respectively. Although the viscosity of CSP solutions decreases with increasing salinity and temperature, there is no sharp drop and the obtained values are suitable even at high salinity and temperature. The hydrophilicity of the sandstone reservoir rock is proportional to the increase in CSP concentration. The contact angle sizes at concentrations of 600, 800, 1000 and 1200 ppm were obtained as 84.98°, 78.04°, 70.39° and 67.69°, respectively. CSP injection under both scenarios reduces the water-cut well and oil recovery is increased by 21.2% and 16.3% by TPC and AP injection, respectively.