Isotopic insights into microbial sulfur cycling in oil reservoirs
Microbial sulfate reduction in oil reservoirs (biosouring) is often associated with secondary oil production where seawater containing high sulfate concentrations (~28 mM) is injected into a reservoir to maintain pressure and displace oil. The sulfide generated from biosouring can cause corrosion of...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2014-09-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00480/full |
| _version_ | 1829507926970073088 |
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| author | Christopher G Hubbard Yiwei eCheng Anna eEngelbrektson Jennifer L Druhan Li eLi Jonathan B Ajo-Franklin John D Coates John D Coates Mark E Conrad |
| author_facet | Christopher G Hubbard Yiwei eCheng Anna eEngelbrektson Jennifer L Druhan Li eLi Jonathan B Ajo-Franklin John D Coates John D Coates Mark E Conrad |
| author_sort | Christopher G Hubbard |
| collection | DOAJ |
| description | Microbial sulfate reduction in oil reservoirs (biosouring) is often associated with secondary oil production where seawater containing high sulfate concentrations (~28 mM) is injected into a reservoir to maintain pressure and displace oil. The sulfide generated from biosouring can cause corrosion of infrastructure, health exposure risks, and higher production costs. Isotope monitoring is a promising approach for understanding microbial sulfur cycling in reservoirs, enabling early detection of biosouring, and understanding the impact of souring. Microbial sulfate reduction is known to result in large shifts in the sulfur and oxygen isotope compositions of the residual sulfate, which can be distinguished from other processes that may be occurring in oil reservoirs, such as precipitation of sulfate and sulfide minerals. Key to the success of this method is using the appropriate isotopic fractionation factors for the conditions and processes being monitored. For a set of batch incubation experiments using a mixed microbial culture with crude oil as the electron donor, we measured a sulfur fractionation factor for sulfate reduction of -30‰. We have incorporated this result into a simplified 1D reservoir reactive transport model to highlight how isotopes can help discriminate between biotic and abiotic processes affecting sulfate and sulfide concentrations. Modeling results suggest that monitoring sulfate isotopes can provide an early indication of souring for reservoirs with reactive iron minerals that can remove the produced sulfide, especially when sulfate reduction occurs in the mixing zone between formation waters containing elevated concentrations of volatile fatty acids and injection water containing elevated sulfate. In addition, we examine the role of reservoir thermal, geochemical, hydrological, operational and microbiological conditions in determining microbial souring dynamics and hence the anticipated isotopic signatures. |
| first_indexed | 2024-12-16T11:16:23Z |
| format | Article |
| id | doaj.art-bc2ae339e411487c9e7ad9bba00d78c6 |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-16T11:16:23Z |
| publishDate | 2014-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-bc2ae339e411487c9e7ad9bba00d78c62022-12-21T22:33:35ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2014-09-01510.3389/fmicb.2014.0048096940Isotopic insights into microbial sulfur cycling in oil reservoirsChristopher G Hubbard0Yiwei eCheng1Anna eEngelbrektson2Jennifer L Druhan3Li eLi4Jonathan B Ajo-Franklin5John D Coates6John D Coates7Mark E Conrad8Lawrence Berkeley National LaboratoryLawrence Berkeley National LaboratoryUniversity of California at BerkeleyStanford UniversityPenn State UniversityLawrence Berkeley National LaboratoryUniversity of California at BerkeleyLawrence Berkeley National LaboratoryLawrence Berkeley National LaboratoryMicrobial sulfate reduction in oil reservoirs (biosouring) is often associated with secondary oil production where seawater containing high sulfate concentrations (~28 mM) is injected into a reservoir to maintain pressure and displace oil. The sulfide generated from biosouring can cause corrosion of infrastructure, health exposure risks, and higher production costs. Isotope monitoring is a promising approach for understanding microbial sulfur cycling in reservoirs, enabling early detection of biosouring, and understanding the impact of souring. Microbial sulfate reduction is known to result in large shifts in the sulfur and oxygen isotope compositions of the residual sulfate, which can be distinguished from other processes that may be occurring in oil reservoirs, such as precipitation of sulfate and sulfide minerals. Key to the success of this method is using the appropriate isotopic fractionation factors for the conditions and processes being monitored. For a set of batch incubation experiments using a mixed microbial culture with crude oil as the electron donor, we measured a sulfur fractionation factor for sulfate reduction of -30‰. We have incorporated this result into a simplified 1D reservoir reactive transport model to highlight how isotopes can help discriminate between biotic and abiotic processes affecting sulfate and sulfide concentrations. Modeling results suggest that monitoring sulfate isotopes can provide an early indication of souring for reservoirs with reactive iron minerals that can remove the produced sulfide, especially when sulfate reduction occurs in the mixing zone between formation waters containing elevated concentrations of volatile fatty acids and injection water containing elevated sulfate. In addition, we examine the role of reservoir thermal, geochemical, hydrological, operational and microbiological conditions in determining microbial souring dynamics and hence the anticipated isotopic signatures.http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00480/fullStable isotopesReservoir Modelingmicrobial sulfate reductionoil reservoirsSouringreactive transport modeling |
| spellingShingle | Christopher G Hubbard Yiwei eCheng Anna eEngelbrektson Jennifer L Druhan Li eLi Jonathan B Ajo-Franklin John D Coates John D Coates Mark E Conrad Isotopic insights into microbial sulfur cycling in oil reservoirs Frontiers in Microbiology Stable isotopes Reservoir Modeling microbial sulfate reduction oil reservoirs Souring reactive transport modeling |
| title | Isotopic insights into microbial sulfur cycling in oil reservoirs |
| title_full | Isotopic insights into microbial sulfur cycling in oil reservoirs |
| title_fullStr | Isotopic insights into microbial sulfur cycling in oil reservoirs |
| title_full_unstemmed | Isotopic insights into microbial sulfur cycling in oil reservoirs |
| title_short | Isotopic insights into microbial sulfur cycling in oil reservoirs |
| title_sort | isotopic insights into microbial sulfur cycling in oil reservoirs |
| topic | Stable isotopes Reservoir Modeling microbial sulfate reduction oil reservoirs Souring reactive transport modeling |
| url | http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00480/full |
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