Surfactant related chemical flooding has great potential for improving oil recovery in carbonate reservoirs, as surfactants are able to effectively lower the oil/water interfacial tension (IFT) and alter wettability toward water-wet. The loss of surfactant during the propagation process in the reservoir is one of the major concerns in determining the feasibility of a chemical flooding project. Many efforts have been made to reduce the surfactant adsorption in various scenarios to make the project economically successful. The addition of polymer in the chemical formulation is commonly used in the applications, which can not only be used to control the water/oil mobility ratio but also affect the surfactant adsorption in different ways.This paper presents the results of a laboratory study on the effect of polymer on reducing the surfactant adsorption onto carbonate reservoir cores. An amphoteric surfactant and a sulfonated polyacrylamide were used in three series of dynamic adsorption tests conducted at reservoir conditions, including surfactant only, polymer followed by surfactant, and mixture of surfactant and polymer (SP). The experimental results showed that when surfactant alone was injected, the surfactant adsorption on the carbonate reservoir cores ranged from 0.125 to 0.203 mg/g-rock, with an average value of 0.163 mg/g-rock. When the surfactant was injected following the injection of a pre polymer slug, the surfactant adsorption reduced to 0.0739 to 0.0848 mg/g-rock, with an average reduction of 51.3%. If SP mixture was injected, the surfactant adsorption ranged from 0.0794 to 0.0872 mg/g-rock, with an average reduction of 48.9%. It indicates that the adsorptions of surfactant and polymer take place competitively on the sites of the rock surfaces. This laboratory study helps understand the synergetic effect of surfactant and polymer in SP formulations and design the injection schemes of chemical flooding processes.
We study decompositions of functions in the Hardy spaces into linear combinations of the basic functions in the orthogonal rational systems fB n g, which are obtained in the respective contexts through Gram-Schmidt orthogonalization process on shifted Cauchy kernels. Those lead to adaptive decompositions of quaternionic-valued signals of finite energy. This study is a generalization of the main results of the first author's recent research in relation to adaptive Takenaka-Malmquist systems in one complex variable.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFor heavy oil reservoirs, the oil viscosity usually varies dramatically during production processes, such as thermal process or solvent injection. This paper presents an investigation of the effect of oil viscosity on relative permeability curves for heavy oil-water systems. Unsteadystate displacement tests were conducted in sandpacks under a typical injection flow rate in a heavy oil recovery process. A series of crude oils with a wide range of viscosities were used in the measurements. Large pore volumes of water were injected to minimize the errors caused by the extrapolation of the recovery data. History matching was used to obtain the relative permeability curves, in which capillary pressure was included. It was found that, for the same injection flow rate, heavy oil-water relative permeability curves systematically shifted with oil viscosity. With increasing oil viscosity, the residual oil saturation increased and the oil and water relative permeabilities decreased at the higher water saturation range. Irreducible water saturation tended to decrease with increasing oil viscosity. Micromodel experiments were conducted to visually investigate the difference in the flow behaviour between heavy oil-water and light oil-water systems. Interacting capillary bundle models were used to analyze the impact of oil viscosity on the residual oil saturation. This work aids in the laboratory measurement and determination of the representative relative permeability curves for heavy oil-water systems, as well as in the proper use of relative permeability curves in reservoir simulation for heavy oil development.
We obtain the octonionic Bergman kernel for half space in the octonionic analysis setting by two different methods. As a consequence, we unify the kernel forms in both complex analysis and hyper-complex analysis.
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