An Experimental Study on Chemical Flooding Using In-Situ Precipitation Inhibitor

摘要

This paper introduces a new in-situ precipitation inhibitor that improves the performance of the conventional ASP flooding. This inhibitor is generated to overcome the precipitation problems prevalent with ASP flooding using brines containing high total dissolved solids. The generated precipitation inhibitor (sodium acrylate) was tested in a chemical formulation containing Alpha Olefin Sulfonate as a surfactant and sodium carbonate as an alkaline. A fluid-fluid compatibility tests were conducted to examine the performance of the precipitation inhibitor using hard brine having large quantity of divalent metal cations. The effect of the precipitation inhibitor on interfacial tension and surfactant adsorption were investigated using various inhibitor concentrations. The in-situ precipitation inhibitor showed an excellent performance in preventing calcium and magnesium precipitations, and solutions remained clear for 45 days at 80°C. The interfacial tension was reduced significantly when the inhibitor was present in the system. As the sodium acrylate concentration is increased to an optimal value, an ultralow interfacial tension of 0.04 mN/m could be achieved. The advantage of the in-situ inhibitor is the use of hard brines without the need for softening the injection water. This could reduce the cost of chemical EOR process and makes it more suitable for environmentally sensitive applications, particularly offshore application.