Methane Production from Natural Gas Hydrates by CO2 Replacement – Review of Lab Experiments and Field Trial

Abstract

Natural gas hydrate is a crystallized ice-like substance, consisting of water and natural gas, with methane as the most common gas. Water molecules form cages through hydrogen bonding and encapsulate gas molecules. Natural gas hydrates are found in the earth under high pressure and low temperature where water and gas co-exist, typically in permafrost and submarine environments. Hydrates have been considered a nuisance in the petroleum industry, creating barriers in pipe lines, and effort has mainly been put into preventing hydrate formation. However, natural gas hydrates are in recent decades acknowledged as a potential energy resource for the future; even conservative estimates suggest 10 15 m 3 CH 4 STP present within hydrate.Several methane production scenarios are proposed: thermal-, chemical-and pressure reduction induced dissociation is available, although depressurization is considered the least costly option. The University of Bergen has since 2002 worked on a fourth alternative: exchange of CH 4 molecules with CO 2 . Lab scale experiments have repeatedly shown CO 2 -CH 4 exchange within sediments. These experiments led to a field trial test in Alaska, operated by ConocoPhillips, by utilizing CO 2 injection as a production method. Similar procedures as in the field test were performed in the lab, creating repetitive data for analysis on lab scale. This paper reviews results from both the laboratory and field pilot and discusses challenges and mitigating measures related to production.

Mechanical properties of gas hydrate-bearing sediments during hydrate dissociation

“…From the year 2002 to 2013, the trial productions of gas hydrate (GH) were conducted at the formations of the permafrost-Mallik and Alaska [1,2], and the deep marine-Nankai Trough [3]. The exploitation of GH leads to the GH dissociation from solid to water and gas, and the loss of bearing capacity of gas hydrate-bearing sediments (GHBS).…”

Investigation into gas production from natural gas hydrate: A review

“…Based on the results of the experimental simulations and numerical simulations on replacement of CH 4 by CO 2 in gas hydrates in sediments in laboratory, the CO 2 -CH 4 replacement in hydrate is thereby expected to be used in field gas production trial, and a work was began to determine a suitable reservoir to conduct such field trial in 2008. [397,398] As mentioned in 5.1.3, on one hand, the reservoir properties in Eileen hydrate in the ANS are suitable for field production; on the other hand, the infrastructure in the place is complete. Consequently, the ANS was chosen as a suitable field location for gas production field trial by CO 2 -CH 4 replacement.…”

“…And depending on how close to hydrate stable condition the bottomhole pressure was, the assisted flowback was divided into another three phases. The detail production period could be seen in reference [397]. During the production period, the gas compositions in the flow steam were determined by using an in-line gas chromatograph.…”

Subsurface injection of combustion power plant effluent as a solid‐phase carbon dioxide storage strategy

“…Previous work suggests that N 2 is either a hydrate inhibitor [Panter et al, 2011] or a hydrate former [Youn et al, 2016;Park et al, 2006], not both. Yet laboratory results [Birkedal et al, 2015;Kang et al, 2014] and the Ignik Sikumi field test [Schoderbek and Boswell, 2011;Hauge et al, 2014;Boswell et al, 2017] hinted that the system evolved in a more complex way than this mutually exclusive binary categorization. Simulations of hydrate exchange at Ignik Sikumi [White and Suk Lee, 2014;Anderson et al, 2014;Hauge et al, 2014] may demonstrate three-phase stability; however, neither the simulations nor the thermodynamic underpinning [Garapati and Anderson, 2014] directly addresses three-phase equilibrium.…”

“…Yet laboratory results [Birkedal et al, 2015;Kang et al, 2014] and the Ignik Sikumi field test [Schoderbek and Boswell, 2011;Hauge et al, 2014;Boswell et al, 2017] hinted that the system evolved in a more complex way than this mutually exclusive binary categorization. Simulations of hydrate exchange at Ignik Sikumi [White and Suk Lee, 2014;Anderson et al, 2014;Hauge et al, 2014] may demonstrate three-phase stability; however, neither the simulations nor the thermodynamic underpinning [Garapati and Anderson, 2014] directly addresses three-phase equilibrium. Furthermore, pseudoternary diagrams of the H 2 O/CH 4 /CO 2 /N 2 system [Garapati and Anderson, 2014] suggest that only Aq-H or H-V two-phase stability is possible.…”