Method of conjugated hydrocarbon gas extraction and storage CO2 in horizontal wellbores

A method of combined extraction of gaseous hydrocarbons and CO 2 storage in horizontal wells which involves drilling a vertical well (1) in the gas-bearing shale deposit (2) located between seams of different types of rock (3), where horizontal or quasi-horizontal wells (4a, 4b, 4c) are drilled off radially at least at two depths, and then the horizontal wells (4b, 4c) are closed with plugs and/or valves controlled from the surface (6b, 6c), into which flexible or semi-flexible small-diameter pipes (7) are brought in via the main vertical (1). The pipes (7) are brought into the lateral wells (4a), and then they are used for injecting cooled, compressed liquid CO 2 , possibly with an admixture of dry sand to maintain fractures, into the gas-bearing shale deposit (2) using a cryogenic pump, while the temperature and pressure in the wells (1) and (4a) are controlled during the CO 2 injection on an ongoing basis by appropriate sensors installed inside them. After this stage is completed, the wells (4a) are also closed with plugs and/or mini-valves controlled from the surface in the vertical pipe, and in the shale deposit (2), the process of CO 2 decompression begins and it undergoes phase transition under the temperature in the deposit, which causes intense shale fracturing, CO 2 adsorption and simultaneous shale gas desorption. Then the lateral wells (4a) are pre-perforated and pressure sensors are installed near the closed lateral wells to enable controlling shale processes. The resulting fractures (5) in the gas-bearing shale deposit (2) enable releasing shale gas which is forced out by heavier CO 2 . The lateral wells (4b, 4c) are opened and the released gas under high pressure comes out via the vertical well (1), and the process of gas recovery from the well can occur spontaneously or be carried out under reduced pressure. The method may also be used for storing CO 2 greenhouse gas after exhaustion of the shale gas deposit in that the gas deposit is shut in permanently by plugging the well at an appropriate height or closing it with a possibility of further use of the deposit.