OIL RECOVERY METHOD OF RESTRAINING GAS CHANNELING DURING CO2 FLOODING PROCESS IN LOW-PERMEABILITY FRACTURED RESERVOIRS THROUGH TWO-STAGE GAS CHANNELING BLOCKING TECHNOLOGY

摘要

The present invention provides a method of restraining gas channeling phenomena during CO2 flooding process in the low-permeability fractured reservoirs through two-stage gas channeling blocking treatment so as to increase oil recovery. The two-stage gas channeling blocking technology includes first-stage gas channeling control to block off fractures using high-strength gel which is formed by natural modified polymeric materials, and second-stage gas channeling control to block off relatively high-permeability layers in the low permeability matrix using aliphatic amine. The gas channeling is effectively controlled and the swept volume is enlarged during the process of CO2 flooding in low permeability fractured reservoirs, and the oil recovery is greatly improved by two-stage gas channeling blocking technology.

主权项

1. A method of restraining gas channeling during CO2 flooding in low-permeability fractured reservoirs through a two-stage gas channeling blocking technology including the following steps:
(1) a first-stage gas channeling blocking treatment, comprising: fractures blocked off using a high-strength gel so as to achieve a first-stage gas channeling control; wherein the high-strength gel is formed by the following parts by mass of materials via graft polymerization and crosslinking: 1-5 parts of a natural modified polymer, 1-5 parts of a monomer, 0.01-0.3 parts of a crosslinking agent, 0.001-0.3 parts of an initiator and 0-0.5 parts of a stabilizer; and (2) a second-stage gas channeling blocking treatment, comprising: relative high permeability layers in a matrix of the low permeability fractured reservoirs in which CO2 channels blocked off using an aliphatic amine to achieve a second-stage gas channeling control.