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First EAGE/IFPEN Conference on Sulfur Risk Management in Exploration and Production
- Conference date: 18 Sep 2018 - 20 Sep 2018
- Location: Rueil-Malmaison, France
- ISBN: 978-94-6282-266-5
- Published: 18 September 2018
21 - 23 of 23 results
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Fe-S-C Dynamics: Re-examining the Role of Reactive Iron Fractions
Authors M. Mertesdorf, T. Wagner and C. MärzOrganic and inorganic geochemical investigations were carried out on samples of Kimmeridge Clay from Yorkshire, UK, to examine the Fe-S-C dynamics that created them. These samples have variable bulk and molecular compositions reflecting differing redox conditions, inputs of iron, and organic matter quantity/quality (TOC up to 18wt%, Type I-II/III kerogen). Reactive iron (FeR) availability is a controlling factor on the sequestration of sulphur into inorganic and organic fractions (Raiswell et al., 1993). Organic matter sulphurisation has economic implications but can also bias the interpretation of organic biomarkers (Kohnen et al., 1991). It has been suggested that sulphide buffering by FeR strongly influences biomarker preservation in bitumen (Reinhardt et al., 2018, on isorenieratene). The effect of individual FeR fractions sulphurisation is investigated. In particular, magnetite does not appear to act as FeR in many samples. This could potentially be a function of the terrigenous input (e.g. magnetite grain size), or caused by its lower reactivity affecting its pyritisation behaviour in less persistently reducing environments. Examining the behaviour of FeR fractions under different conditions and their effects on organic matter sulphurisation is essential to improving our understanding of FeR and biomarker proxies and their biases.
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Controls on the Magnitude of TSR Derived Hydrogen Sulphide in the Marrat Reservoir, Northern Kuwait
Authors M. Al-Hajeri, H. Akbar, A. Bishop, L. Gao and Y. TangSignificant concentrations of hydrogen sulphide (H2S) are observed in the Marrat reservoir in the Raudhatain and Sabriya fields (northern Kuwait). In this study, we have attempted to determine the origin of H2S and what factors may control its relative concentration. Our data show that it is most likely a product of thermochemical sulphate reduction (TSR). However, this process has not gone to completion, as the levels of H2S in the samples studied are still below 5%. Additionally, the hydrocarbon constituents of the gas phase do not appear to have been severely affected by TSR. So far, this process has primarily impacted the oil phase: increasing oil gravity and decreasing oil sulphur content. Some of the Marrat fluids from the Sabriyah field have lower H2S concentrations, though with equivalent H2S sulphur isotopic compositions to the other Marrat fluids from Raudhatain. We hypothesize that these differences are related to original compositional grading and/or reservoir charge histories, which influence the degree of TSR alteration by virtue of differences in original fluid polar and associated labile sulphur contents. This study demonstrates that pre-TSR reservoir charge histories and fluid phase distributions should be taken in to account for effective evaluation of H2S occurrences.
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Keynote Lecture - Biogeochemistry of Sulfur: an Overview
By J. WerneSulfur is an essential element for all living organisms because it plays a critical role in energy transduction, enzymatic reactions, and biosynthesis (amino acids and proteins). Organic matter preserved in sediments thus retains the organic and inorganic history of sulfur initially incorporated into organic tissue (primary) or added during diagenesis (secondary). The organic sulfur (OS) formed by these processes is the second largest pool of reduced sulfur in sediments; in some systems, such as the Miocene Monterey Formation, as much as 80% of the total reduced sulfur is present in the form of organic sulfur. The record of varying organic carbon burial, with its implications for carbon and nutrient sequestration, surface redox balance, and oxidation of the atmosphere potentially depends in large part on details of marine sulfur chemistry.
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