Biodiesel as Surfactant Additive in Steam Assisted Recovery of Heavy-Oil and Bitumen

Abstract

Abstract Use of additives to improve the efficiency of thermal heavy-oil and bitumen recovery processes has been studied extensively over the decades. Two common types of additives used in thermal applications, mainly steam assisted recovery, are solvents and surfactants. Commercial use of solvents have setbacks due to their high costs and retrieval difficulties. Cost and stability of the surfactants under reservoir operating temperature and pressure are the major concerns. We propose the use of biodiesels such as fatty acids methyl esters as a surfactant additive reducing heavy oil/bitumen-water interfacial tension in steam assisted recovery processes. Advantages of using biodiesel as a surfactant additive are that biodiesel is chemically stable under the operating pressure and temperature of the reservoir, it causes no harm on bitumen quality and release water chemistry and its use is economically feasible. We have conducted a series of steam assisted bitumen recovery experiments to clarify the additional recovery potential and efficiency improvement capacity of biodiesel. High pressure steam at 1.8 MPa pressure, 205 °C was used in these tests at a 900 g/h feed rate. The porous media used was a normal grade oil sands ore obtained from a surface mine operation in northern Alberta, Canada. Oil sands ore was packed in a basket and placed in a high pressure cell. Bitumen recovery experiments were performed by spraying canola oil fatty acid methyl ester on oil sands ore at a 2 g/kg-bitumen dosage. These tests show that bitumen recovery efficiency increases over 40%. In another series of tests, tall oil fatty acids methyl ester was injected into a high pressure steam line at a 7.4 g-biodiesel/kg-steam dosage. Because of the solubility of biodiesel in bitumen, the effect of biodiesel on bitumen recovery could not be accurately concluded. Vapor pressure measurements performed on canola oil and tall oil derived biodiesel samples suggest that saturation compositions of biodiesel in steam at 1.8 MPa pressure and 205 °C are at least one order of magnitude higher than the requested biodiesel dosages. Further tests are planned by reducing biodiesel dosages to about 1 g and 0.5 g-biodiesel/kilogram-steam and by monitoring the solubility of biodiesel in bitumen.