Mechanism of enhanced oil recovery by nanoparticles extracted from flowback fluids of acidizing oil wells

The silicates in flowback fluids from acidizing oil wells can be used as raw materials for the synthesis of nanomaterials, that are beneficial for the treatment of produced water and enhanced oil recovery. In this paper, the nanomaterials were synthesized from acidizing flowback fluids by sol-gel method and the reaction conditions were optimized. The interfacial tension, wetting angle and surface tension of the solution were measured. The test of displacement efficiency and flooding experiments were conducted in two dimensional flat cores to reveal the mechanism of enhanced oil recovery by nanoparticles. The results indicated that the nanoparticles with a diameter of 351nm could be extracted and synthesized from acidizing flowback solution at low pH. Compared with other nanomaterials, the synthesized nanoparticles could change the interfacial properties between oil and water due to the complex acidizing process. When the injection concentration of nanoparticles reached 300mg/L, the decrease of water cut reached the maximum, up to 27.16%, and the recovery rate during subsequent water flooding was 32.25%. Appropriately increasing the injection concentration of nanoparticles extracted from acidizing flowback fluids was beneficial to improve the recovery rate, so that realizing the efficient development of oil and gas resources. The research results can provide a new method for the treatment of oilfield wastewater.