Efficiency enhancements in methane recovery from natural gas hydrates using injection of CO2/N2 gas mixture simulating in-situ combustion

Swanand S. Tupsakhare and Marco J. Castaldi

Applied Energy, 2019, vol. 236, issue C, 825-836

Abstract: Thermal stimulation was combined with an injection of a mixture of CO2 (85%) + N2(15%) to investigate efficiency enhancements from pure thermal stimulation and thermal stimulation with CO2 injection approaches. Tests were performed at initial hydrate saturation of 10% and 300 ml/min CO2 + N2 injection rate with three different heating rates of 20, 50 and 100 W. The results indicate that thermal stimulation with CO2 + N2 injection is the most efficient method available for methane gas recovery. At 10% Hydrate Saturation (SH) and 100 W heating rate, the number of moles of CH4 recovered increased from 8.5 to 16 to 20 in the case of thermal stimulation, thermal stimulation with CO2 exchange and thermal stimulation with CO2 + N2 exchange respectively. The experimental results reported here are aligned with model and Raman spectroscopy predictions in terms of replacement mechanism and recovery efficiency, reported in the literature. The results obtained from CO2/N2 composition ratio show that in the exchange process, CO2 first replaces CH4 in the large cages of Structure I hydrates followed by N2 targeting CH4 in the small cages of Structure I hydrates. This replacement mechanism has been predicted in the literature by Liu et al. (2016) using Molecular Dynamics simulations. It is also found from this work that N2 is selectively captured in hydrate cages below 12 °C. The values of carbon sequestration index (defined as moles of CO2 sequestered divided by moles of CH4 recovered) were 0.32, 0.52 and 0.85 respectively for 100, 50 and 20 W heating tests. The data obtained from our work in terms of gas composition, methane recovery and CO2 sequestered is consistent with the key findings reported in the literature.

Keywords: Gas hydrates; Carbon capture; Natural gas; Energy recovery; Methane hydrates; CO2/N2 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (23)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0306261918318348
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:236:y:2019:i:c:p:825-836

Ordering information: This journal article can be ordered from
http://www.elsevier.com/wps/find/journaldescription.cws_home/405891/bibliographic
http://www.elsevier. ... 405891/bibliographic

DOI: 10.1016/j.apenergy.2018.12.023

Access Statistics for this article

Applied Energy is currently edited by J. Yan

More articles in Applied Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().