A method to recover natural gas hydrates with geothermal energy conveyed by CO2

A geothermal-assisted CO2 replacement method (GACR) was proposed, in which ambient-temperature CO2 is injected from the well head of a heat exchange well to the wellbore in geothermal reservoir for heating, and the heated CO2 then flows upward into the hydrate bearing layer (HBL) to accelerate the n...

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Bibliographic Details
Published in:Energy (Oxford) 2018-02, Vol.144, p.265-278
Main Authors: Liu, Yongge, Hou, Jian, Zhao, Haifeng, Liu, Xiaoyu, Xia, Zhizeng
Format: Article
Language:English
Subjects:
Ambient temperature
Carbon dioxide
Carbon sequestration
CO2 replacement
Computer simulation
Gas hydrates
Geothermal energy
Heat exchange
Heat exchange well
Heat transfer
Heating
Hydrates
Mathematical models
Natural gas
Natural gas hydrate
Pressure reduction
Reservoirs
Stimulation
Storage
Temperature effects
Thermal stimulation
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Summary:A geothermal-assisted CO2 replacement method (GACR) was proposed, in which ambient-temperature CO2 is injected from the well head of a heat exchange well to the wellbore in geothermal reservoir for heating, and the heated CO2 then flows upward into the hydrate bearing layer (HBL) to accelerate the natural gas hydrate (NGH) dissociation. The GACR method, which is low-carbon and environment-friendly, requires no surface heating, recovers NGHs by means of combined thermal stimulation and CO2 replacement, and meanwhile achieves CO2 storage. Then a numerical simulation model was developed to investigate the heat exchange performance of the heat exchange well, the development performance of HBL, the CO2 storage performance and factors affecting such a development process. Calculations indicate that the temperature of the returned CO2 heated by the geothermal reservoir at the entry of HBL can be up to 68.9 °C, far beyond the temperature of HBL. Hence, GACR can fulfill the NGH recovery combining thermal stimulation and CO2 replacement. Compared with the depressurization method and the case with no geothermal reservoir, the cumulative CH4 production after 20 years of development can increase by 305% and 51.9% respectively, with a CO2 storage volume of 2.11 × 107 m3 and a storage factor of 14.5%. •The GACR method which can both recover geothermal energy and HBLs was proposed.•A numerical simulation model of GACR was built.•The robustness of GACR was proved.•Factors affecting the development performance of GACR were analyzed.
ISSN:0360-5442
1873-6785
DOI:10.1016/j.energy.2017.12.030