Unique chemical and isotopic characteristics and origins of natural gases in the Paleozoic marine formations in the Sichuan Basin, SW China: Isotope fractionation of deep and high mature carbonate reservoir gases

Zhang, Shuichang; He, Kun; Hu, Guoyi; Mi, Jingkui; Ma, Qisheng; Liu, Keyu; Tang, Yongchun

doi:10.1016/j.marpetgeo.2017.02.010

Cited by 60 publications

(57 citation statements)

References 54 publications

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“…The Neoproterozoic to Lower Cambrian black shales widely occur around the world and have attracted great interest from geologists and geochemists because of the economic importance of petroleum exploration potential and geological implications (Grosjean, Love, Kelly, Taylor, & Summons, ; Grosjean, Love, Stalvies, Fike, & Summons, ; Huang, Zhang, & Su, ; Suryendu, Sharmila, & Srinivasan, ; Zhang et al, ). This potential has been confirmed by the discoveries of some industrial petroleum fields in many countries, particularly in China (Chen et al, ; Huang et al, ; Zhang et al, ), Oman (Grantham, ; Grosjean et al, ), western India (e.g., Suryendu et al, ), eastern Siberia (e.g., Kelly, Love, Zumberge, & Summons, ), and Australia (Logan, Summons, & Hayes, ). Besides, the Ediacaran–Cambrian (E–C) black shales also indicate the significant transition from Precambrian Era to the Phanerozoic, which is marked by tectonic readjustments and palaeoceanographic, palaeoclimatic, and biological conversion (Craig et al, ).…”

Section: Introductionmentioning

confidence: 99%

Main factors controlling the organic matter enrichment in the Lower Cambrian sediments of the Sichuan Basin, SW China

Wang

Tian

et al. 2019

Geological Journal

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The Lower Cambrian Qiongzhusi Formation contains more than 200 m of marine sediments mainly consisting of mudstone and black shales, which are widely accepted as the most important hydrocarbon source rocks of the Ediacaran–Cambrian giant gas field in the Sichuan Basin. The geochemical compositions of biomarkers and trace elements obtained from black shales at the bottom of the Qiongzhusi Formation were used to reconstruct the palaeoproductivity and palaeoenvironment and to determine the main factors controlling the deposition and preservation of this organic‐rich shales. Based on varieties of steroids and hopanoids compositions, multifarious palaeobios such as pelagophyceae, dinoflagellate, diatom (or its ancestor), sponges, and aerobic/anaerobic bacteria have been proved to evolve in the Early Cambrian in the Sichuan Basin. In addition, a relative high concentration of Cubio compared with modern oceanic palaeoproductivity proxies indicate a moderate to relatively high palaeoproductivity, which is favourable for the organic matter accumulation of this source rocks. Moreover, the evidence from biomarkers and trace element ratios suggest that the Lower Cambrian sediments were deposited under a non‐sulphurized anoxic condition, which provided a favourable preservation condition. The covariation among Porg, Cubio, and TOC shows that the palaeoproductivity is the main controlling factor for the high organic content of the black shales of the Qiongzhusi Formation.

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Section: Introductionmentioning

confidence: 99%

Main factors controlling the organic matter enrichment in the Lower Cambrian sediments of the Sichuan Basin, SW China

Wang

Tian

et al. 2019

Geological Journal

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“…In recent years, the black shale which is similar to the Longmaxi Formation has been found in several shale gas fields such as Fuling, Changning, and Weiyuan. The methane and ethane carbon isotopes of the shale gas are significantly reversed [62,63]. The main reason for this reversal is the mixing of gas cracked from the liquid hydrocarbons in the high mature/overmature stages of the shale and the gas degraded from the kerogen in the early stage [63,64], which is also supported by widely distributed solid asphaltenes in shale [1].…”

Section: Potential Of Cracked Gas From Residual Oil In Sourcementioning

confidence: 98%

“…The methane and ethane carbon isotopes of the shale gas are significantly reversed [62,63]. The main reason for this reversal is the mixing of gas cracked from the liquid hydrocarbons in the high mature/overmature stages of the shale and the gas degraded from the kerogen in the early stage [63,64], which is also supported by widely distributed solid asphaltenes in shale [1]. The thermogenic shale gas is a kind of unconventional gas mainly distributing in the organic-rich shale with a thickness greater than 15 m and value within 1.1%∼3.0%.…”

Section: Potential Of Cracked Gas From Residual Oil In Sourcementioning

confidence: 99%

New Insight into the Kinetics of Deep Liquid Hydrocarbon Cracking and Its Significance

Zhao

Zhang

et al. 2017

Geofluids

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The deep marine natural gas accumulations in China are mainly derived from the cracking of liquid hydrocarbons with different occurrence states. Besides accumulated oil in reservoir, the dispersed liquid hydrocarbon in and outside source also is important source for cracking gas generation or relayed gas generation in deep formations. In this study, nonisothermal gold tube pyrolysis and numerical calculations as well as geochemical analysis were conducted to ascertain the expulsion efficiency of source rocks and the kinetics for oil cracking. By determination of light liquid hydrocarbons and numerical calculations, it is concluded that the residual bitumen or hydrocarbons within source rocks can occupy about 50 wt.% of total oil generated at oil generation peak. This implies that considerable amounts of natural gas can be derived from residual hydrocarbon cracking and contribute significantly to the accumulation of shale gas. Based on pyrolysis experiments and kinetic calculations, we established a model for the cracking of oil and its different components. In addition, a quantitative gas generation model was also established to address the contribution of the cracking of residual oil and expulsed oil for natural gas accumulations in deep formations. These models may provide us with guidance for gas resource evaluation and future gas exploration in deep formations.

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“…The carrier gas was helium (He, flowrate=1 mL/min). At the beginning, the GC oven temperature was 30 • C and kept there for 10 minutes, then raised to 180 • C (rate of 10 • C/min) and held for 20-30 minutes [87][88][89][90][91][92][93].…”

Section: Analysis Of Molecular Compositionmentioning

confidence: 99%

“…The stable carbon isotope values are recorded in the customary "δ" notation in per mil (% ) relative to the Vienna Pee Dee Belemnite (VPDB) standard. The value of ± 0.5% should be the reproducibility and analytical precision with respect to the VPDB standard [87][88][89][90][91][92][93]. A Finnigan MAT 253 mass spectrometer with the GC-TC-IRMS method was used to ascertain the stable hydrogen isotope.…”

Section: Analysis Of Stable Carbon and Hydrogen Isotopementioning

confidence: 99%

Characteristics and Origins of the Natural Gas and Implications for Gas-Source Correlation in Deep Formations of the Songliao Basin, NE China

Peng²,

Feng

et al. 2019

Energies

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The Songliao Basin is the most productive petroliferous lacustrine basin in NE China, and numerous large gas fields with large proven reserves occur in its deep formations. However, considerable challenges remain: (1) the origins and genetic types of the natural gases are controversial; (2) the gas-source correlations are poorly studied; and (3) the migration distance is vague. In this study, these problems are addressed by the study of the gas compositions, light hydrocarbons, and stable hydrogen and carbon isotopes. The gases are predominantly of organic and thermogenic origins. The Huoshiling (J3h) and Shahezi (K1sh) gases are mainly mixtures of coal-derived and oil-associated gases and the mixed-sources of primary kerogen degradation and secondary oil cracking, while the Yingcheng (K1yc) gases are mainly coal-derived gases and predominantly derived from primary kerogen degradation. The gases in different sags are derived from the source rocks developed in the same sags where the gases accumulated, characterized by the proximal-source accumulation. Vertically, the gases in the J3h and K1sh are predominantly sourced by the proximal J3h and K1sh mudstones, while the gases in the K1yc are mainly derived from either the J3h or the K1sh source rocks, suggesting the gas migration with short distances.

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Unique chemical and isotopic characteristics and origins of natural gases in the Paleozoic marine formations in the Sichuan Basin, SW China: Isotope fractionation of deep and high mature carbonate reservoir gases

Cited by 60 publications

References 54 publications

Main factors controlling the organic matter enrichment in the Lower Cambrian sediments of the Sichuan Basin, SW China

Main factors controlling the organic matter enrichment in the Lower Cambrian sediments of the Sichuan Basin, SW China

New Insight into the Kinetics of Deep Liquid Hydrocarbon Cracking and Its Significance

Characteristics and Origins of the Natural Gas and Implications for Gas-Source Correlation in Deep Formations of the Songliao Basin, NE China

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