Application of a non-ionic bio-surfactant instead of chemical additives for prevention of the permeability impairment of a swelling sandstone oil reservoir

Abstract

Formation damage is a general term, which refers to any process that reduces the production or injectivity of an oil well. Clay swelling formation damage, due to incompatible fluid invasion, is a common problem in the petroleum industry. In this research, the effect of Acanthophyllum root extract (ACRE), a bio-based surfactant, on the reduction in reservoir permeability impairment has been studied. Some static tests were applied to investigate the chemical interaction between the surfactant and montmorillonite (Mt), including Mt sedimentation test, Free swelling index (FSI) test, Zeta potential tests, particle size measurement, and scanning electron microscopy (SEM). Experiments were followed by coreflood and micromodel tests to verify their effect on preventing permeability reduction and pore plugging in porous media. According to the results, Mt dispersion is unstable in the presence of ACRE solution. ACRE can reduce the FSI from 233.3 (totally hydrated Mt) to 94.3%, representing the reduction in hydration potential. The zeta potential of Mt in ACRE aqueous solution moves toward the lowest magnitude, implying that the water molecules surrounding the Mt particles are unstable. Particle size measurement and SEM analysis proved simultaneously that ACRE solution sustains Mt particles flocculated and prevents delamination. The thermal stability of the ACRE was evaluated by thermogravimetric analysis (TGA), and it showed a suitable resistance to the temperature rise. Eventually, coreflood and micromodel tests revealed that ACRE has a high performance in lowering the permeability impairment and pore plugging. All in all, ACRE showed high potential in preventing Mt swelling and, therefore, formation damage in clay-bearing sandstones.