Generation and Stability of Microemulsion to Improve Heavy Oil Recovery by Waterflooding with Chemical Additives at Cold Conditions

Abstract

Thermal methods which are commonly applied to recover heavy oil have many limitations such as heat loss to thin or deep reservoirs due to temperature difference found in different parts of reservoirs, difficulty in recovering oil in low permeability deposits, high energy and water waste, and so forth. To solve these issues, nonthermal heavy oil recovery method, which is chemical flooding by in-situ emulsification, was investigated in this extensive study. Commercially available chemicals along with chemicals synthesized in the lab were first screened for their capacity to generate stable Winsor type 4 heavy oil-in-water emulsions using glass tube tests and microscopic visualization experiments. After the initial screening, stabilization tests and concentration tests were conducted for the purpose of cost optimization. Selected chemicals were then further synthesized to create Nano-fortified Pickering emulsions to create even stronger emulsions stability that can survive harsh reservoir conditions. Created complex Pickering solutions were then injected into glass bead samples, sandpacks, Berea sandstone cores, slim tube sandpacks at various rates in order to test and ensure their strength to generate in-situ heavy oil-in-water emulsions in porous media of various types. A novel, environmentally friendly, cost-effective chemical flooding method using biodiesel condensate (Biodiesel-in-water emulsion) was also investigated for its ability to recover heavy oil by in-situ heavy oil-in-water emulsion generation. Lastly, hard brines were introduced in the study to better simulate the real reservoir brine conditions and understand the impact that divalent ions can have on emulsion stability. Research results demonstrated that Pickering solutions, biodiesel-in-water emulsions, hardness resistant chemicals can help recover oil by heavy oil-in-water emulsification in porous media. Full Winsor type 4 emulsion production and significant increase in recovery could be observed with the addition of low concentration polymer (0.35%) as an emulsion stabilization agent to chemicals injected for sandpack flooding experiments at hard brine of low and high ii salinity conditions. These results confirmed polymer’s potential as a robust co-emulsification agent that can significantly help improve heavy oil recovery.