Temperature and injection water source influence microbial community structure in four Alaskan North Slope hydrocarbon reservoirs

Abstract

A fundamental knowledge of microbial community structure in petroleum reservoirs can improve predictive modeling of these environments. We used hydrocarbon profiles, stable isotopes, and high-density DNA microarray analysis to characterize microbial communities in produced water from four Alaskan North Slope hydrocarbon reservoirs. Produced fluids from Schrader Bluff (24–27°C), Kuparuk (47–70°C), Sag River (80°C), and Ivishak (80–83°C) reservoirs were collected, with paired soured/non-soured wells sampled from Kuparuk and Ivishak. Chemical and stable isotope data suggested Schrader Bluff had substantial biogenic methane, whereas methane was mostly thermogenic in deeper reservoirs. Acetoclastic methanogens (Methanosaeta) were most prominent in Schrader Bluff samples, and the combined δD and δ13C values of methane also indicated acetoclastic methanogenesis could be a primary route for biogenic methane. Conversely, hydrogenotrophic methanogens (e.g., Methanobacteriaceae) and sulfide-producing Archaeoglobus and Thermococcus were more prominent in Kuparuk samples. Sulfide-producing microbes were detected in all reservoirs, uncoupled from souring status (e.g., the non-soured Kuparuk samples had higher relative abundances of many sulfate-reducers compared to the soured sample, suggesting sulfate-reducers may be living fermentatively/syntrophically when sulfate is limited). Sulfate abundance via long-term seawater injection resulted in greater relative abundances of Desulfonauticus, Desulfomicrobium, and Desulfuromonas in the soured Ivishak well compared to the non-soured well. In the non-soured Ivishak sample, several taxa affiliated with Thermoanaerobacter and Halomonas predominated. Archaea were not detected in the deepest reservoirs. Functional group taxa differed in relative abundance among reservoirs, likely reflecting differing thermal and/or geochemical influences.

Simulation of Deepwater Horizon oil plume reveals substrate specialization within a complex community of hydrocarbon degraders

“…Detailed protocols are provided in Supporting Information. Data from the resulting .CEL files were processed through PhyCA using the same bacterial Stage1 and Stage2 cutoffs as previously described (30).…”

“…The 16S rRNA gene was amplified using bacterial primers 27F/1492R and archaeal primers 4Fa/1492R (30), with annealing temperatures from 50 to 56°C. Bacterial PCR product (500 ng) and archaeal PCR product (25 ng) were hybridized to each array following previously described procedures (4).…”

Novel haloalkaliphilic methanotrophic bacteria: An attempt for enhancing methane bio-refinery

“…Despite no member of Halomonas genus has been reported as a methane oxidizer, members of this genus possess a highly versatile metabolism and are typically found in methane rich environments such as hydrocarbon reservoirs, methane seeps or methane rich sediments ((Niederberger et al, 2010;Piceno et al, 2014)). Under optimal growth conditions (pH 9, 6 % NaCl and 30 ºC), maximum specific methane removal rates of 25.3 ± 1.2 mg CH 4 g biomass -1 h -1 were achieved during the exponential growth phase, values similar to those recorded in other methanotrophic bacteria (Cantera et al, 2016;Gebert et al, 2003).…”

Geo-Biological Coupling of Authigenic Carbonate Formation and Autotrophic Faunal Colonization at Deep-Sea Methane Seeps I: Geo-Biological Settings

“…During diagenetic thermogenesis of methane, carbon and hydrogen isotopes are subject to discrimination or fractionation, as occurring in biological methanogenesis, too; however, the tendency and degree of isotope fractionations are distinguishable between geological and biological methanogenesis, as described in detail in Section 3.1. Generally, thermogenic methane has more 13 C and 2 H (deuterium, D), that is, higher (enriched) δ 13 C and δD, respectively, than biogenic methane does [28].…”