Technological aspects of the development of gas hydrate deposits with the use of carbon dioxide injection

Abstract

The article is dedicated to the technological peculiarities of natural gas hydrate deposits extraction with using perspective method which consists of introduction of carbon dioxide into the gas hydrate layer removing methane and creating CO2 hydrate. Specific attention is paid to the insufficient efficiency of presently used methods in terms of the economic effect and safety of gas extraction. The complex methodological approach has been used to experimentally determine the optimal pressure of the two gases swap based on the minimal time of the process duration. The rate of the two gases exchange in the reactor has been defined and a new technological solution as to the gas hydrate deposits recovery has been proposed. It is defined that at the pressure being equal to Р = 9 MPa and the temperature Т = +7…+8 ºC, the whole exchange of the guest molecules СН4 for СО2 molecules can be reached in 2 hours. It is established that the gas hydrate crystallisation centres nucleate in about 30 – 35 minutes, after that the crystals continue growing removing methane from the preliminary created hydrate up to the point when about 70 – 80% of the hydrate is filled with СО2 hydrate. The lowest rate of the exchange process took place under the pressure Р = 5 MPa and temperature Т = +7…+8 ºC and resulted in 10 hours. The penetration length of the carbon dioxide jet is established depending on the process duration under the optimal injection pressure of СО2. A new technological scheme is introduced for methane recovery from gas hydrate deposits of the Black Sea with the help of carbon dioxide injection into the hydrate seam.