2026-10-11T06:12:17Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34033392 2026-09-30T15:15:04Z category_146 category_16 category_272 category_873 category_39 category_45 category_69 category_132 category_135 portal_63 item_type_6 month_year_09_2026

Production of Secondary Microbial Methane from a Gas Hydrate-Bearing Reservoir at the HYDRATE P1 Production Test Well (PTW-1) on the Alaskan North Slope John W. Pohlman (8033798) Michael Casso (11331889) Lee-Gray Boze (25144626) William F. Waite (24726071) Steven C. Phillips (25144629) Carolyn Ruppel (819152) Melanie Holland (16274127) Jun Yoneda (2869745) Motoi Oshima (8113961) Akihiro Hiruta (10006501) Timothy S. Collett (24726068) Space Science Physiology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Ecology Sociology Inorganic Chemistry Infectious Diseases Computational Biology unexpectedly high ratio sv6 stratigraphic horizon subsequent depressurization achieved prudhoe bay field pressure cores collected kuparuk state 7 deep sadlerochit formation alaskan north slope electrical submersible pump secondary microbial methane differentiate primary microbial prudhoe bay unit duration production test gas composition transitioned gas hydrate stability unit b ), b1 sand reservoir secondary microbial unit b much methane gas composition mostly primary jet pump b1 sand hydrate gas gas produced gas hydrate well cuttings water observed rich sediments rich hydrate project conducted mostly indistinguishable measured depth gdw ), d1 sand caged gases bounding units 3558 ft 3113 ft 1968 ft 151 days 12 site 1133 ft Gas hydrate in the Alaskan North Slope (ANS) is believed to contain as much methane as the known conventional gas accumulations in the Prudhoe Bay field. The JOGMEC-DOE-USGS Collaborative Gas Hydrate R&D Project conducted an extended-duration production test from the sub-permafrost, gas-hydrate saturated B1 sand reservoir (unit B) at the Kuparuk State 7-11-12 Site in the Prudhoe Bay Unit of the ANS. Using compositional and stable isotopic data measured on gas produced from well cuttings and pressure cores collected from the HYDRATE 02 Geo Data Well (GDW), we differentiate primary microbial, secondary microbial, and trace thermogenic gas sources. The upper part of the well contained predominantly primary microbial methane from near the surface to the SV6 stratigraphic horizon at 1133 ft (345.3 m) measured depth (MD). Below that, the gas composition transitioned to a mixture of mostly primary and secondary microbial methane to near the base of ice-bearing permafrost at 1968 ft (599.8 m) MD. With greater depth to 3558 ft (1084.5 m) MD, which includes the D1 sand (unit D), the B1 sand (unit B), and the base of gas hydrate stability at 3113 ft (948.8 m) MD, the gas composition was greater than 98% secondary microbial methane with the remainder being oil-associated thermogenic gas migrated from the deep Sadlerochit Formation. The unit B vertical gas profile derived from degassed pressure cores demonstrated that gas dissolved in the clay-rich sediment intervals bounding the B1 sand reservoir was distinct from dissolved and hydrate-caged gases in the sand-rich hydrate-bearing reservoir. The HYDRATE P1 Production Test Well (PTW-1) targeted and successfully extracted gas dissociated from hydrate gas in the B1 sand for 151 days when using an electrical submersible pump to depressurize the reservoir with subsequent depressurization achieved through the use of a jet pump. Gas produced from PTW-1 was mostly indistinguishable from the gas compositional profile measured through the B1 sand and generally distinct from dissolved gas in the bounding clay-rich sediments, confirming that the upper and lower bounding units limited infiltration into the reservoir during production. Isolation of the bounding units from the reservoir contributed to the unexpectedly high ratio of production gas to water observed during the extended-duration gas hydrate production test at PTW-1. 2026-09-30T00:00:00Z Text Journal contribution 10.1021/acs.energyfuels.5c06364.s001 https://figshare.com/articles/journal_contribution/Production_of_Secondary_Microbial_Methane_from_a_Gas_Hydrate-Bearing_Reservoir_at_the_HYDRATE_P1_Production_Test_Well_PTW-1_on_the_Alaskan_North_Slope/34033392 CC BY-NC 4.0