Sulphur stable isotope systematics in diagenetic pyrite from the North Sea hydrocarbon reservoirs revealed by laser combustion analysis

Fallick, A.E., Boyce, A. and McConville, P. (2012) Sulphur stable isotope systematics in diagenetic pyrite from the North Sea hydrocarbon reservoirs revealed by laser combustion analysis. Isotopes in Environmental and Health Studies, 48(1), pp. 144-165. (doi: 10.1080/10256016.2012.658791)

Abstract

Our study focuses on pyrite nodules developed in the Brent Group sandstones, which host the Brent Oilfield, one of the North Sea's greatest oil and gas producers. Timing of nodule formation is equivocal, but due to the forceful, penetrative textures that abound, it is considered late. This pyrite offers a research opportunity because it records the development of the supply of H₂S in a hydrocarbon reservoir and its sulphur isotopic composition. Laser-based analysis of δ³⁴S reveals an extraordinary diversity in values and patterns. The values range from−27 to+72‰, covering half the terrestrial range, with large variations at the submillimetre scale. Isotopically heavy (δ³⁴S +30‰ or higher) sulphide is endemic, but low δ³⁴S pyrite is also present and appears to represent a temporally though not spatially (on the cm scale) distinct pyritisation event. The distribution of δ³⁴S values within individual concretions can be normal (Gaussian), but in some cases may reflect progressive isotope fractionation process(es), conceivably of Rayleigh type. The source of the sulphur and the identity of the isotope fractionation process(es) remain

• Item Type: Articles
• Additional Information: Special Issue: Dedicated to Heimo Nielsen
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Boyce, Professor Adrian and Fallick, Professor Anthony
• Authors: Fallick, A.E., Boyce, A., and McConville, P.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Isotopes in Environmental and Health Studies
• ISSN: 1025-6016
• ISSN (Online): 1477-2639
• Published Online: 22 February 2012