New equation to decipher the relationship between carbon isotopic composition of methane and maturity of gas source rocks

Chen, Jianping; Wang, Xulong; Chen, Jianfa; Ni, Yunyan; Xiang, Baoli; Liao, Fengrong; He, Wenjun; Yao, Limiao; Li, Erting

doi:10.1007/s11430-020-9692-1

Cited by 24 publications

(11 citation statements)

References 37 publications

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“…Moreover, δ 13 C 1 ‰ can provide information on the maturity of organic matter. Stahl 41 , Schoell 42 , and Chen et al 43 established quantitative relationships between δ 13 C 1 ‰ and R o for oil-type gas. Based on these relationships, the Longmaxi shale can be classified as generally overmature, with R o exceeding 2.0% (Fig.…”

Section: Resultsmentioning

confidence: 99%

“… ( a ) Relationship between the carbon isotope composition of methane and hydrocarbon composition of natural gas generated by lipoids (modified after Stahl and Carey 46 and Li et al 47 ). ( b ) Relationship between δ 13 C 1 ‰ and Ro for oil-type gas (modified after Chen et al 43 ). The carbon isotopic composition of methane is mainly distributed between the ordinates corresponding to the two horizontal dotted lines.…”

Section: Resultsmentioning

confidence: 99%

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Application of mathematical statistics to shale gas-bearing property evaluation and main controlling factor analysis

Pang

et al. 2022

Sci Rep

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Gas-bearing property evaluation and main controlling factor analysis have remained a concern in shale gas research. The application of principal component analysis, an important mathematical statistical method, in gas-bearing property evaluation and main controlling factor analysis of the Longmaxi shale in the Weirong area, Sichuan Basin, was examined. The Longmaxi shale exhibits high heterogeneity, manifested in the organic matter abundance, mineral composition, and pore structure. Seven geological factors, including the temperature, pressure, TOC content, clay content, brittle mineral content, pore volume, and specific surface area (SSA), were selected in principal component analysis. Four principal components with geological significance, such as mineral composition, formation condition, pore structure, and organic matter abundance, were extracted through principal component analysis, and further constituted a comprehensive factor. Shale gas-bearing properties were evaluated according to the score of the comprehensive factor. The Longmaxi shale could be identified as exhibiting good, medium, and poor gas-bearing properties based on the comprehensive factor scores of these samples. According to each geological factor’s contribution to the comprehensive factor, combined with geological analysis, it could be considered that gas-bearing properties are primarily controlled by pore volume, SSA, and clay content, followed by TOC content, brittle mineral content, temperature and pressure.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Application of mathematical statistics to shale gas-bearing property evaluation and main controlling factor analysis

Pang

et al. 2022

Sci Rep

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“…During the pyrolysis of organic matter, the dryness coefficient of natural gas increases as organic matter becomes more thermally evolved. Many researchers therefore use the dryness coefficient or humidity coefficient of natural gas to measure the maturity of natural gas [ 22 , 58 , 59 ]. Dai et al [ 60 ] summarized the relationship between organic vitrinite reflectance and the humidity coefficient as Ro = −0.419lnW + 1.908.…”

Section: Resultsmentioning

confidence: 99%

Carbon Isotope Fractionation Characteristics of Normally Pressured Shale Gas from the Southeastern Margin of the Sichuan Basin; Insights into Shale Gas Storage Mechanisms

Yang

Xiao

et al. 2022

Nanomaterials

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Since the development of shale gas in the Wufeng–Longmaxi Formation in the Sichuan Basin, China’s shale gas production and reserves have increased rapidly. The southeastern margin of the Sichuan Basin is located in a normally pressured transition zone, where single well gas production varies greatly under complex geological structures. In order to reveal the shale gas enrichment mechanism and favorable shale gas regions, shale gas samples from production wells were collected from different structures, with the formation pressure coefficient ranging between 0.98 and 1.35. The gas components and carbon isotope characteristics of normally pressured shale gas were investigated. The carbon isotope characteristics of the Wufeng–Longmaxi shale gas from the basin scale was mainly controlled using thermal maturity; as the thermal maturity increased, heavier carbon isotopes were found, in addition to drier shale gas. For normally pressured shale gas, the composition of δ13C1 and δ13C2 becomes heavier, and the dryness coefficient decreases with the decreasing pressure coefficient; this is not consistent with the results from thermal evolution. By comparing possible influencing factors, it is evident that the change in geological structure destroys the original shale gas reservoir, which leads to the escape of some gases, and it may be the main factor that contributes to the gas geochemical characteristics of the normally pressured shale gas. Compared with the geological parameters of the shale samples, such as mineral composition, organic abundance, organic pore distribution, and gas content, the carbon isotope characteristics of normally pressured shale gas show a higher efficiency, thus indicating favorable sweet spot evaluations for shale gas in the studied areas.

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“…As extensively studied before, the stable carbon isotopes of hydrocarbon gases have favorable correlations with the thermal maturity of their source rocks. ,,,, According to the geological observations and numerous statistics in the lacustrine basins of China, Chen et al have proposed a semilogarithmic equation between the δ 13 C 1 value and vitrinite reflectance (% Ro) Equation is for oil-associated gas and eq is for coal-derived gas. According to these two equations, the source rock maturity can be estimated (Table ).…”

Section: Discussionmentioning

confidence: 99%

Characteristics of Source Rocks and Genetic Origins of Natural Gas in Deep Formations, Gudian Depression, Songliao Basin, NE China

Li³

et al. 2022

ACS Earth Space Chem.

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Numerous large gas fields with large proven reserves occur in the deep formations of Songliao Basin, NE China. However, some challenges remain as follows: (1) the main source rock is poorly studied and (2) the origins and genetic types of the natural gases are controversial. In this study, these problems can be addressed by the research of the paleoenvironments during shale deposition, the organic matter sources, the source rock potential, the gas origin and genetic type, and gas–source correlations. The redox conditions of the water column during the Huoshiling to Yingcheng depositions were transitional (suboxidizing to subreducing) environments, and the Huoshiling deposition corresponded to reducing conditions. The paleosalinity of water was brackish to fresh from Huoshiling to Yingcheng depositions. The organic matters of the Huoshiling–Yingcheng shales mainly originated from terrigenous and/or lacustrine materials. The shales are evaluated as the fair to good source rock potential, and the Huoshiling is the best. The gases in the Huoshiling and Shahezi were mainly organic and thermogenic origins, with some inorganic origins. The gases of organic origins are mainly the mixed sources of coal-derived and oil-associated gases and are predominant products of secondary cracking, suggesting the well gas exploration potential in deep formations of Songliao Basin. The gases in the Shahezi formation are predominantly sourced by the Shahezi shales, indicating an approaching-source accumulation.

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New equation to decipher the relationship between carbon isotopic composition of methane and maturity of gas source rocks

Cited by 24 publications

References 37 publications

Application of mathematical statistics to shale gas-bearing property evaluation and main controlling factor analysis

Application of mathematical statistics to shale gas-bearing property evaluation and main controlling factor analysis

Carbon Isotope Fractionation Characteristics of Normally Pressured Shale Gas from the Southeastern Margin of the Sichuan Basin; Insights into Shale Gas Storage Mechanisms

Characteristics of Source Rocks and Genetic Origins of Natural Gas in Deep Formations, Gudian Depression, Songliao Basin, NE China

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