Experimental Study of Steam Surfactant Flood for Enhancing Heavy Oil Recovery After Waterflooding

Steam injection with added surface active chemicals is one of general EOR processes aimed to recover residual oil after primary production processes. It has been demonstrated that, after waterflooding, an oil swept area can be increased by steam surfactant flow due to the reduced steam override effect as well as reduced interfacial tension between oil and water in the formation. To investigate the ability to improve recovery of 20.5oAPI California heavy oil with steam surfactant injection, several experiments with a one-dimensional model were performed. Two experimental models with similar porous media, fluids, chemicals, as well as injection and production conditions, were applied. The first series of experiments were carried out in a vertical cylindrical injection cell with dimensions of 7.4 cm x 67 cm. The second part of experiment was conducted using a horizontal tube model with dimensions of 3.5 cm x 110.5 cm. The horizontal model with a smaller diameter than the vertical injection cell is less subject to channel formation and is therefore more applicable for the laboratory scale modeling of the one-dimensional steam injection process. Nonionic surfactant Triton X-100 was coinjected into the steam flow. For both series of experimental work with vertical and horizontal injection cells, the concentration of Triton X-100 surfactant solution used was chosen 3.0 wt%. The injection rates were set to inject the same 0.8 pore volumes of steam for the vertical model and 1.8 pore volumes of steam for horizontal model. The steam was injected at superheated conditions of 200oC and pressure of 100 psig. The liquid produced from the separator was sampled periodically and treated to determine oilcut and produced oil properties. The interfacial tension (IFT) of the produced oil and water were measured with an IFT meter and compared to that for the original oil. The experimental study demonstrated that the average incremental oil recovery with steam surfactant flood is 7 % of the original oil-in-place above that with pure steam injection.