Inorganic gel enhanced oil recovery in high temperature reservoir

L-III reservoir belongs to Weizhou 11-1 Oilfield in South China. The reservoir temperature is high, about 140 degrees C. In addition, the distance between oil well and water well is large and the platform operation space is limited. These factors limit the application of polymer gel profile control and oil displacement technology. In this paper, inorganic gel is used as profile control and oil displacement agent, it was characterized using rheometer, XRD and SEM. Ca2+ and Mg2+ ions in seawater react with the Na2O center dot SiO2 solution to form C-S-H and M-S-H inorganic gels. They have good suspension properties and strong transport ability in porous media. Under high temperature conditions, the gels volume shrinkage and the structure is compact. The inorganic gel coating on the surface of the rock skeleton by "-Si-O-Si-" ionic bond, which achieves deep placement and plays an important role on fluid diversion. When the core permeability is 1500 x 10(-3)mu m(2) and concentration of Na2O center dot SiO2 is 0.73%, the pressure gradient ratios of inorganic gel plugging in each interval are from 1.074 to 4.724, and the plugging rate in the first half of core can exceed 84%. Using the size and composition of the inorganic gel slug: "0.01PV isolation liquid +0.05PV Na2O center dot SiO2 solution +0.01PV isolation liquid +0.05PV seawater", the above agents are injected alternately for 6 times, the recovery rate of inorganic gel profile control and oil displacement increased to 23.87%. These results provide theoretical and technical support for the development of inorganic gel and its application in wells.