Abstract: A method of underground storage of an injection gas containing CO2 gas and enhanced oil recovery includes: supplying injection water through a water flow path; jetting the injection water as a high-pressure water jet which is increased in velocity by narrowing a fluid flow through a fine bubble-generating device placed at a lower end of the water flow path; suctioning an injection gas through a gas flow path by a negative pressure generated by the Venturi effect downstream of the high-pressure water jet; jetting the injection gas as fine bubbles from the fine bubble-generating device placed at a lower end of the gas flow path; and performing underground storage of the injection gas by allowing a gas-liquid mixed fluid containing fine bubbles generated by mixing the injection water with the fine bubbles in the fine bubble-generating device to penetrate into a permeable formation such as an oil reservoir.

Abstract: A method of underground storage of an injection gas containing CO2 gas and enhanced oil recovery includes: supplying injection water through a water flow path; jetting the injection water as a high-pressure water jet which is increased in velocity by narrowing a fluid flow through a fine bubble-generating device placed at a lower end of the water flow path; suctioning an injection gas through a gas flow path by a negative pressure generated by the Venturi effect downstream of the high-pressure water jet; jetting the injection gas as fine bubbles from the fine bubble-generating device placed at a lower end of the gas flow path; and performing underground storage of the injection gas by allowing a gas-liquid mixed fluid containing fine bubbles generated by mixing the injection water with the fine bubbles in the fine bubble-generating device to penetrate into a permeable formation such as an oil reservoir.

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.