Surface geochemistry

Investigating the Behavior of Sedimentary Mercury (Hg) During Burial‐Related Thermal Maturation

“…Both elevated TOC and TS values are typical in sediments rich in labile organic matter, which may also contain substantial amounts of Hg. As discussed previously, labile organic matter can undergo transformation as a result of thermal stress (burial) and form mobile hydrocarbon and non‐hydrocarbon phases that can be expelled from the sedimentary section where they are formed, resulting in an overall decrease in the amount of original TOC and consequent rock‐mass loss (Dembicki, 2022; Lewan et al., 1979; Raiswell & Berner, 1987; Tissot & Welte, 1984). Although it is difficult to know precisely how much of the original organic‐carbon of the Posidonienschiefer sediments in our study has been lost during maturation, using the reconstruction method of Jarvie (2012), we estimate that up to 50% of the original TOC in cores B and C may have been reduced as a result of kerogen conversion and hydrocarbon expulsion.…”

“…As sediments become buried, the organic matter initially undergoes diagenesis, which eliminates functional groups and moieties that are primarily oxygen‐ and nitrogen‐containing, resulting in a resistant macromolecular residue (kerogen) and sulfur (Tissot & Welte, 1984). This kerogen can be further broken down into lower molecular weight hydrocarbon species, such as oil and gas, through the process of thermal cracking (Dembicki, 2022; Peters et al., 2005; Tissot & Welte, 1984). As the kerogen becomes more thermally “mature” it progresses through the stages of oil and gas generation and, depending on the type of kerogen, potentially loses up to 60% of its organic‐matter mass due to secondary migration of the generated products away from the host rock (Dembicki, 2022; Lewan et al., 1979; Raiswell & Berner, 1987; Tissot & Welte, 1984).…”

“…Fine‐grained organic‐rich sediments (typically shales and coals) commonly contain labile organic matter inherited from the original biomass (e.g., algal and vascular plant matter). Such sediments were often deposited under reducing conditions that enhanced the preservation of OM by hindering its degradation and remineralization (see e.g., Bohacs et al., 2020; Dembicki, 2022; Tissot & Welte, 1984). These deposits commonly are source rocks for petroleum as the labile organic matter can undergo transformation, converting to oil and gas as a result of burial and exposure to thermal stress (Dembicki, 2022).…”

“…This kerogen can be further broken down into lower molecular weight hydrocarbon species, such as oil and gas, through the process of thermal cracking (Dembicki, 2022; Peters et al., 2005; Tissot & Welte, 1984). As the kerogen becomes more thermally “mature” it progresses through the stages of oil and gas generation and, depending on the type of kerogen, potentially loses up to 60% of its organic‐matter mass due to secondary migration of the generated products away from the host rock (Dembicki, 2022; Lewan et al., 1979; Raiswell & Berner, 1987; Tissot & Welte, 1984). With sufficient burial and extended exposure to high basinal temperatures, the original kerogen ultimately ends up as a carbon‐rich graphitic residue, having lost most of its labile organic matter as expelled H‐rich hydrocarbon species.…”

Restoration of the Production in a Dead Well by using Low Cost Recompletion of Sand Control

“…Hydrocarbons come from the decomposition of organic material (animals and plants) [1][2][3][4]. This organic material is transported by rivers and is deposited at the bottom of the seas or large continental lakes, which are the places where hydrocarbons are formed [5][6][7][8][9].…”