An innovative method for the characterization of oil content in lacustrine shale-oil systems: A case study from the Middle Permian Lucaogou Formation in the Jimusaer Sag, Junggar Basin

Liu, Yazhou; Zeng, Jianhui; Yang, Guangqing; Jia, Wanting; Liu, Shengnan; Kong, Xianjing; Li, Shengqian

doi:10.1016/j.marpetgeo.2021.105112

Cited by 15 publications

(10 citation statements)

References 50 publications

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“…The Junggar Basin was at middle-to-high latitudes in Central Asia during Paleozoic–Cenozoic and experienced continuing tectonic evolution (Figure a) . The Jimusar Sag is classified as a subordinate structural unit in the southeastern Junggar Basin (Figure b) . The total area of this sag is approximately 1280 km 2 . , …”

Section: Geological Settingmentioning

confidence: 99%

“…(a) Location of the Junggar Basin during the Middle Permian (modified from Cao et al). (b) The location of the Jimusar Sag in the southern Junggar Basin (modified from Cao et al …”

Section: Geological Settingmentioning

confidence: 99%

“…The Jimusar Sag is a remarkable shale oil source area and has been studied extensively in previous literature studies. , Tectonically, strata from the Carboniferous to the Quaternary in the Jimusar Sag were deposited, and the sag has experienced Hercynian, Indosinian, Yanshan, and Himalayan orogenies. , The LCG Fm. in the Jimusar Sag was deposited from 267 to 270 Ma and its average sedimentation rate is between 89 and 103 m/Myr .…”

Section: Geological Settingmentioning

confidence: 99%

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Differences between Laminated and Massive Shales in the Permian Lucaogou Formation: Insights into the Paleoenvironment, Petrology, Organic Matter, and Microstructure

Yang

Zeng

Qiao

et al. 2022

ACS Earth Space Chem.

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The Permian Lucaogou Formation (LCG Fm.) in the Junggar Basin is an organic-rich source rock interval formed in a salinized paleolake, and organic-rich laminated and massive shales are broadly deposited. However, the paleoenvironment difference between laminated and massive shales is still unclear, and the effect of this difference on petrology, pore structure, and organic matter enrichment is significant to shale oil resource evaluation. In this study, organic and element geochemistry, mineralogy, and nitrogen adsorption are used to analyze key differences between laminated and massive shales. The results show that most shale samples present mature thermal stage and oil-prone type II kerogen. Felsic igneous rocks in the continental island arc are their primary mineral component sources. The differences between laminated and massive shales are mainly from their silica origin, paleoclimate, and salinity. The silica origin in laminated shale is primarily from the terrestrial debris influx, while the massive shale is mixed with terrestrial debris and biogenic origin. The silica origin from hydrothermal activities is negligible. The laminated shale prefers to be deposited in a hot and dry climate with weak weathering and relatively higher salinity. However, the massive shale is mainly deposited in a warm and humid climate with moderate weathering and lower salinity conditions. For both laminated and massive shales from the LCG Fm., the warm and humid climate is beneficial to organic matter (OM) accumulation. Paleoproductivity presents an increasingly positive impact on source rocks when the rock fabric transforms from massive to thick laminae. Overall, lower salinity, humid climate, and strong terrigenous clastic input jointly enhance organic matter (OM) accumulation in both laminated and massive shales. Arid and semiarid climates are beneficial to improving the fractability of both laminated and massive shales. The laminated shale presents a relatively wider average nanopore diameter and lower pore volume than massive samples. These findings provide an important insight into the correlation between organic enrichment, laminae, pore structure, and depositional environment. This study has profound implications for understanding the formation mechanisms of laminated and massive shales in the lacustrine paleoenvironment.

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Section: Geological Settingmentioning

confidence: 99%

“…(a) Location of the Junggar Basin during the Middle Permian (modified from Cao et al). (b) The location of the Jimusar Sag in the southern Junggar Basin (modified from Cao et al …”

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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Differences between Laminated and Massive Shales in the Permian Lucaogou Formation: Insights into the Paleoenvironment, Petrology, Organic Matter, and Microstructure

Yang

Zeng

Qiao

et al. 2022

ACS Earth Space Chem.

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“…Liu et al proposed a new enrichment evaluation method, namely, the oil content evaluation index (OCEI). 27 In the OCEI method, the evaluation index (Li*) represents the liquid hydrocarbon content per unit rock mass. The evaluation index (CI*) represents the oil-bearing area given the core description, and the evaluation index (GI*) represents the content of gaseous hydrocarbons (C 1 −C 5 ) in a constant volume.…”

Section: Introductionmentioning

confidence: 99%

“…Liu et al proposed a new enrichment evaluation method, namely, the oil content evaluation index (OCEI) . In the OCEI method, the evaluation index (Li*) represents the liquid hydrocarbon content per unit rock mass.…”

Section: Introductionmentioning

confidence: 99%

Innovative Standard for Graded Evaluation of Oil Enrichment of Lacustrine Shale: A Case Study of the Lower Third Member of the Shahejie Formation, Zhanhua Sag, Eastern China

et al. 2021

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The exploration and production results of lacustrine shale oil are closely related to shale oil enrichment evaluation. However, there exists a lack of rapid and accurate oil enrichment evaluation methods for strongly heterogeneous lacustrine shale. In this study, an innovative standard for graded evaluation of shale oil enrichment is proposed. In the innovative standard, considering the light hydrocarbon loss of shale oil, the free oil (S 1) content is corrected for light hydrocarbons. Moreover, on the basis of the hydrocarbon expulsion threshold theory, and combined with the specific geochemical characteristics of the shale in the study area, the lacustrine shale oil mobility threshold OSI (the oil saturation index) is determined to replace the fixed empirical shale oil mobility threshold (100 mg/g). By combining the absolute oil content (S 1) with the relative oil content (OSI), we are able to divide the shale oil resources into four categories: enriched resources, moderately enriched resources, low-efficient resources, and ineffective resources. This standard is successfully applied to evaluate the oil enrichment degree of the lower third member (Es3 L) of the Shahejie Formation in well Luo 69 of the Zhanhua Sag, Bohai Bay Basin. The oil enrichment degrees of shales with varying kerogen compositions and distinct lithofacies are highly diverse. Shale comprising type I kerogen is the most conducive to shale oil enrichment. However, more than 15% of the tested shales composed of type II1 kerogen include enriched and moderately enriched resources, which should be considered. Organic-fair laminated calcareous shale (OFLCS) is the most favorable lithofacies type for shale oil enrichment. The development of bedding structures and a moderate organic matter content are beneficial for shale oil enrichment. This standard is suitable for graded evaluation of the oil enrichment degree of strongly heterogeneous lacustrine shale worldwide.

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Impact of petroleum expulsion and evaporation losses on shale oil assessment using pyrolysis techniques

You,

Liu,

Song

et al. 2023

Geological Journal

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Shale reservoirs contain petroleum that undergoes losses through oil expulsion and evaporation, with uncertain implications on shale oil reserves and mobility evaluation. This study focuses on understanding the influence of these losses on open‐system pyrolysis, the primary method for assessing shale oil content and mobility. Comprehensive analyses were performed on 26 lacustrine shale samples from the Chang7 Member, encompassing total organic carbon (TOC), programmed pyrolysis, solvent extraction, and gas chromatography–mass spectrometry (GC–MS). The research examines the impact of petroleum losses on petroleum fractions, the oil saturation index (OSI), and multi‐step pyrolysis outcomes. The findings indicate that Chang7 shale with TOC content above 7% experiences more substantial petroleum losses than those with TOC below 7%. Petroleum losses result in significant fractional distillation of crude oil in the shale, leading to the deterioration of shale oil properties and a notable reduction in free oil content in S1, ultimately causing a decline in OSI values. As a result, Chang7 shale with TOC below 7% demonstrates a higher potential for shale oil recovery, whereas Chang7 shale with TOC exceeding 7% should be considered more significant as a hydrocarbon source rock. Moreover, multi‐step pyrolysis is not suitable for assessing petroleum mobility in shale with low free oil content (OSI values below 100 mg/g). This limitation arises from the loss of free low‐boiling components in Chang7 shale, and the currently detected low‐boiling pyrolysis products may predominantly exist in an adsorbed state.

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An innovative method for the characterization of oil content in lacustrine shale-oil systems: A case study from the Middle Permian Lucaogou Formation in the Jimusaer Sag, Junggar Basin

Cited by 15 publications

References 50 publications

Differences between Laminated and Massive Shales in the Permian Lucaogou Formation: Insights into the Paleoenvironment, Petrology, Organic Matter, and Microstructure

Differences between Laminated and Massive Shales in the Permian Lucaogou Formation: Insights into the Paleoenvironment, Petrology, Organic Matter, and Microstructure

Innovative Standard for Graded Evaluation of Oil Enrichment of Lacustrine Shale: A Case Study of the Lower Third Member of the Shahejie Formation, Zhanhua Sag, Eastern China

Impact of petroleum expulsion and evaporation losses on shale oil assessment using pyrolysis techniques

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