Enhanced oil recovery method using injection well including two passages

Abstract

The method enables enhanced recovery of oil contained in an underground oil reservoir by using an injection well including two passages of a water passage and a gas passage. The enhanced oil recovery method includes steps of injecting an injection water from the water passage, injecting an injection gas from the gas passage and spraying the injection gas as a fine gas bubble flow through a micro-bubble generator which is installed at a lower end of the gas passage, and penetrating into the underground oil reservoir a gas-liquid mixture fluid containing micro-bubbles generated by mixing the injection water and the fine gas bubble flow in the injection well.

1 . An enhanced oil recovery method for enhanced recovery of oil contained in an underground oil reservoir by using an injection well including two passages of a gas passage and a water passage arranged inside the gas passage, the enhanced oil recovery method comprising:
 a step of injecting injection water from the water passage;   a step of injecting an injection gas from the gas passage and spraying the injection gas as a fine gas bubble flow through a micro-bubble generator which is installed at a lower end of the gas passage; and   a step of penetrate into the underground oil reservoir a gas-liquid mixture fluid containing micro-bubbles generated by mixing the injection water and the fine gas bubble flow in the injection well, wherein   the micro-bubble generator is positioned at a depth of the underground oil reservoir, and   the injection gas is injected between an inside of the gas passage and an outside of the water passage.   
     
     
         2 . The enhanced oil recovery method according to  claim 1 , wherein
 the water passage is a water injection pipe, and the gas passage is a gas injection pipe.   
     
     
         3 .- 5 . (canceled)