A geochemical investigation of the free and carbonate-bound organic matter in the clay-sized fraction of argillaceous source rocks and its significance for biogenic interpretation

Zhao, Yue; Cai, Jingong; Lei, Tingwu; Yang, Yongying

doi:10.1007/s12182-018-0257-7

Cited by 6 publications

(3 citation statements)

References 66 publications

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“…At temperatures above 400 °C, the relative abundance of compound D has an obvious upward trend. This phenomenon may be attributed to the release of these bicyclic alkanes from the insoluble organic matrix (kerogen) (Noble et al 1987;Zhao et al 2018) at this stage, and the rate of hydrocarbon expulsion is higher than the rate of conversion from compound D to compound C. In addition, the relative abundance of compound C does not change significantly, indicating that the process of the formation of compounds C by isomerization reactions (D → C) and the process of conversion C → B may reach a dynamic balance. However, the relative abundance of compound B shows a certain downward trend.…”

Section: Discussion Of the Possible Formation Mechanism Of Bicyclic Smentioning

confidence: 99%

Evolution and organic geochemical significance of bicyclic sesquiterpanes in pyrolysis simulation experiments on immature organic-rich mudstone

Yan

Liu

et al. 2019

Pet. Sci.

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Sesquiterpanes are ubiquitous components of crude oils and ancient sediments. Liquid saturated hydrocarbons from simulated pyrolysis experiments on immature organic-rich mudstone collected from the Lower Cretaceous Hesigewula Sag were analyzed by gas chromatography-mass spectrometry (GC-MS). C 14 bicyclic sesquiterpanes, namely, 8β(H)-drimane, 8β(H)-homodrimane, and 8α(H)-homodrimane were detected and identified on basis of their diagnostic fragment ions (m/z 123, 179, 193, and 207), and previously published mass spectra data, and these bicyclic sesquiterpanes presented relatively regular characteristics in their thermal evolution. The ratios 8β(H)-drimane/8β(H)-homodrimane, 8β(H)-homodrimane/8α(H)homodrimane, and 8β(H)-drimane/8α(H)-homodrimane all show a clear upward trend with increasing temperature below the temperature turning point. Thus, all these ratios can be used as evolution indexes of source rocks in the immature-lowmaturity stage. However, the last two ratios may be more suitable than the first ratio as valid parameters for measuring the extent of thermal evolution of organic matter in the immature-low-maturity stage because their change amplitude with increasing temperature is more obvious.

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Section: Discussion Of the Possible Formation Mechanism Of Bicyclic Smentioning

confidence: 99%

Evolution and organic geochemical significance of bicyclic sesquiterpanes in pyrolysis simulation experiments on immature organic-rich mudstone

Yan

Liu

et al. 2019

Pet. Sci.

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“…6a. The samples show a complete n-alkane series from nC 13 to nC 33 with a modest bimodal pattern which indicates an input of both aquatic algal and terrigenous OM (Bourbonniere and Meyers, 1996;Zhao et al, 2018). The carbon number peak varies from C 17 to C 20 .…”

Section: Molecular Geochemistry Of the Chang 7 Member (Table 2)mentioning

confidence: 98%

Source Rock Potential of the Upper Triassic Chang 7 Member in the Western Ordos Basin, China

Chen

Wang

Yang³

et al. 2022

Journal of Petroleum Geology

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The Chang 7 member of the Upper Triassic Yanchang Formation is an important source rock in the Ordos Basin, NW China. Previous studies of the unit have in general focused on the relatively deep‐water (∼25 m) anoxic, OM‐rich lacustrine mudstones which form the main Mesozoic source rock at fields in the south of the basin. However, this paper presents an integrated geochemical investigation of the relatively shallow‐water Chang 7 facies in a study area around Jiyuan field in the western part of the basin in order to evaluate its source rock potential. The results show that the Chang 7 source rock in the study area has a high content of Type II OM, and is interpreted to have been deposited in a suboxic‐anoxic lacustrine setting with a mixed input of aquatic and terrigenous organic matter. The results of 1D modelling of a well in the study area showed that the Chang 7 member entered the oil generation window from the Middle Jurassic. Oil‐oil correlations based on hierarchical cluster analysis and correspondence analysis showed that crude oils generated by deep‐water Chang 7 source rocks from wells in the south of the basin can be distinguished from Soxhlet‐extracted petroleum from reservoir sandstones in the study area. The compositional differences are inferred to be due to variations in source rock facies compositions. An oil – source rock correlation study showed that the shallower‐water Chang 7 source rock in the western part of the basin generated the hydrocarbons in core extracts of reservoir sandstones from wells in this area. The shallow‐water Chang 7 facies may therefore constitute an effective oil‐prone source rock in the western Ordos Basin.

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“…The OSI (S 1 /TOC × 100) is the most used and most effective one. The OSI is based on traditional Rock-Eval pyrolysis, by which the rock samples are heated to 300 and 600 °C to obtain parameters S 1 , S 2 , and T max . , When the OSI > 100 mg HC/g TOC (TOC: total organic carbon), the oil can flow effectively, and the tight/shale reservoir is considered as a potential exploration area. The phenomenon is known as the “oil crossover effect”, and the higher the OSI is, the more content of movable oil will be.…”

Section: Introductionmentioning

confidence: 99%

Oil Mobility Evaluation of Fine-Grained Sedimentary Rocks with High Heterogeneity: A Case Study of the Lucaogou Formation in the Jimusar Sag, Junggar Basin, NW China

et al. 2023

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The oil mobility in unconventional tight/shale oil reservoirs is complex because of the high heterogeneity in the matrix pore structure and connectivity. Thus, it is difficult to evaluate hydrocarbon exploration potential precisely. In this study, multistep temperature pyrolysis (MTP) Rock-Eval and 1D (dimensional) as well as 2D nuclear magnetic resonance (NMR) techniques were employed to systematically characterize the oil mobility in lacustrine fine-grained sedimentary rocks from the Lucaogou Formation in the Jimusar Sag, Junggar Basin, NW China. The results show that the Lucaogou Formation fine-grained sedimentary rocks can be subdivided into six types of lithofacies. With the increase of organic matter richness, the content of adsorbed oil increases, whereas the content of movable oil increases first and tends to stabilize (when total organic carbon (TOC) > 4%). This is because when TOC is low, the fine-grained sedimentary rocks need to self-adsorb before oil production; when TOC increases further, the generated oil will break through the absorption limit and charge into the adjacent reservoirs; therefore, the movable oil ceases to increase. Permeability is found to have a greater impact on movable fluid saturation than porosity. Meanwhile, good throat radius and pore connectivity are conducive to oil flow as movable oil is more sensitive to throats rather than pores. Furthermore, a higher content of brittle minerals is not necessarily favorable for oil flow; alternatively, more clay minerals are easy to from cements causing pore blockage, which will essentially hinder oil mobility. Overall, the organic matter content, reservoir pore structure, and rock mineral composition are the main factors affecting tight/shale oil mobility. On the basis of the above research, a conceptual model of oil mobility in different lithofacies’ reservoirs is established. These results have a reference significance for evaluating oil recoverability in fine-grained sedimentary rocks.

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A geochemical investigation of the free and carbonate-bound organic matter in the clay-sized fraction of argillaceous source rocks and its significance for biogenic interpretation

Cited by 6 publications

References 66 publications

Evolution and organic geochemical significance of bicyclic sesquiterpanes in pyrolysis simulation experiments on immature organic-rich mudstone

Evolution and organic geochemical significance of bicyclic sesquiterpanes in pyrolysis simulation experiments on immature organic-rich mudstone

Source Rock Potential of the Upper Triassic Chang 7 Member in the Western Ordos Basin, China

Oil Mobility Evaluation of Fine-Grained Sedimentary Rocks with High Heterogeneity: A Case Study of the Lucaogou Formation in the Jimusar Sag, Junggar Basin, NW China

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