Oil displacement method for an ultra-high water-cut reservoir

Abstract

An oil displacement method for an ultra-high water-cut reservoir, including the following steps: injecting water into the reservoir to carry out a water flooding until water cut of the reservoir is greater than 90%; injecting a polymer solution and a supercritical carbon dioxide oil displacement agent, respectively; injecting water to carry out water flooding after injection of the polymer solution or the supercritical carbon dioxide oil displacement agent is completed; where injection amounts of both the polymer solution and the supercritical carbon dioxide oil displacement agent are not less than 0.1 PV, and a total injection amount of the polymer solution and the supercritical carbon dioxide oil displacement agent is 0.3-1.2 PV; and a viscosity ratio of the polymer solution to a crude oil in the reservoir is 1:(0.8-10), and a viscosity ratio of the supercritical carbon dioxide oil displacement agent to the crude oil in the reservoir is 1:(10-800).

Dependencies are inferred from the claim text.