Abstract: For thin and bottom water reservoir, the U-like distribution pattern of remained oil is likely formed in condition of water drive, allowing the injected water to flowing down to the bottom water layer, hence decreasing the oil-displacement efficiency. This paper presents such an idea for allowing the injected water to flowing up to the top of U-like watered-out area by adding suitable chemical agent into the reservoir and making it react with Ca²⁺ and Mg²⁺ in formation water, resulting in gradually forming low permeable zones. The bottom-water modeling equipment is used to simulate the feasibility of such a reaction between silica-calc complex agent (SCAP) and the calcium and magnesium ions for forming low permeable zone, for the purpose of enhancing oil recovery (EOR).

Key words: thin and bottom water reservoir, U-like waterflood model, driving pressure, silica-calc complex plugging agent, particle gel