The Iġnik Sikumi Field Experiment, Alaska North Slope: Design, Operations, and Implications for CO₂–CH₄ Exchange in Gas Hydrate Reservoirs

Abstract

the program were to (1) determine the feasibility of gas injection into hydrate-bearing sand reservoirs and (2) observe reservoir response upon subsequent flowback in order to assess the potential for CO 2 exchange for CH 4 in naturally occurring gas hydrate reservoirs. Initial modeling determined that no feasible means of injection of pure CO 2 was likely, given the presence of free water in the reservoir. Laboratory and numerical modeling studies indicated that the injection of a mixture of CO 2 and N 2 offered the best potential for gas injection and exchange. The test featured the following primary operational phases: (1) injection of a gaseous phase mixture of CO 2 , N 2 , and chemical tracers; (2) flowback conducted at downhole pressures above the stability threshold for native CH 4 hydrate; and (3) an extended (30-days) flowback at pressures near, and then below, the stability threshold of native CH 4 hydrate. The test findings indicate that the formation of a range of mixed-gas hydrates resulted in a net exchange of CO 2 for CH 4 in the reservoir, although the complexity of the subsurface environment renders the nature, extent, and efficiency of the exchange reaction uncertain. The next steps in the evaluation of exchange technology should feature multiple well applications; however, such field test programs will require extensive preparatory experimental and numerical modeling studies and will likely be a secondary priority to further field testing of production through depressurization. Additional insights gained from the field program include the following: (1) gas hydrate destabilization is self-limiting, dispelling any notion of the potential for uncontrolled destabilization; (2) gas hydrate test wells must be carefully designed to enable rapid remediation of wellbore blockages that will occur during any cessation in operations; (3) sand production during hydrate production likely can be managed through standard engineering controls; and (4) reservoir heat exchange during depressurization was more favorable than expectedmitigating concerns for near-wellbore freezing and enabling consideration of more aggressive pressure reduction.

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

“…We simulate various other thermodynamic conditions (squares and diamonds, Figure ) and present the variability of the phase diagrams as a function of pressure and temperature (Figures S4 and S5). Our simulated thermodynamic conditions are comparable to the experimental conditions of other studies (cross marks, Figure ) summarized in Table S1, including the field test at Ignik Sikumi [ Schoderbek and Boswell , ; Boswell et al , ], on the northern slope of Alaska, U.S. (≈85 bar, ≈4°C).…”

Mechanisms of Methane Hydrate Formation in Geological Systems

“…One volume of methane hydrate can release about 160 to 180 volume of methane gas at standard temperature and pressure (Boswell & Collett, ; Collett et al, ; Sloan, ). Gas hydrate production tests have been recently conducted in deep marine hydrate systems, such as the Nankai Trough offshore Japan (Yamamoto et al, ) and the South China Sea (Li et al, ), on the Alaska North Slope (Boswell et al, ; Hunter et al, ), and in northern Canada at the Mallik Site (Ashford et al, ; Figure ). It remains to be seen whether hydrate deposits can be economically produced (Boswell & Collett, ).…”

Study on the Effects of Heterogeneous Distribution of Methane Hydrate on Permeability of Porous Media Using Low‐Field NMR Technique

“…Natural gas hydrates are mainly distributed in the continental margin and permafrost (Chong et al, ). As an unconventional resource, natural gas hydrates are amendable to potential commercial natural gas production due to its huge reserves (Boswell et al, ). The natural gas hydrates exploitation has been a key focus of the development of energy industry in some countries (Zhao et al, ).…”