Shale oil potential of lacustrine black shale in the Eocene Dongying depression: Implications for geochemistry and reservoir characteristics

Liang, Chao; Cao, Yingchang; Jiang, Zaixing; Wu, Jin-Hui; Song, Guoqi; Wang, Yongshi

doi:10.1306/01251715249

Cited by 89 publications

(65 citation statements)

References 44 publications

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“…The depositional mechanisms of fine‐grained sediments include mass flow, bottom currents, and suspension deposition (Abouelresh & Slatt, ; Liang, Cao, Jiang, Wu, & Song, ; Liang et al, ; Loucks & Ruppel, ; Shanmugam, ; Yang, He, et al, ; Yang, Fan, Han, & Van Loon, ). A previous study showed that seven lithofacies were identified in the lower Silurian Longmaxi shale of Sichuan Basin (Liang et al, ): laminated calcareous mudstone, laminated carbonaceous mudstone, laminated silty mudstone, laminated claystone, laminated siliceous shale, siltstone, and massive mudstone.…”

Section: Discussionmentioning

confidence: 99%

Source analysis of quartz from the Upper Ordovician and Lower Silurian black shale and its effects on shale gas reservoir in the southern Sichuan Basin and its periphery, China

Han

Jiang

et al. 2018

Geological Journal

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A major breakthrough in shale gas exploration and development has been made concerning the black shale of the Upper Ordovician and Lower Silurian. In recent years, significant progresses have been made regarding the exploration and development of shale gas in the black shale of the Upper Ordovician and Lower Silurian. Accordingly, we investigated the petrological and geochemical characteristics of the black shale from WF2‐LM5 graptolite biozones and performed a source analysis of quartz as well as evaluated its effect on shale gas reservoirs. The black shale mainly contains clay, carbonate, and quartz with the average TOC of 2.21%. Three quartz types, Q1, Q2, and Q3, were identified via petrological and cathodoluminescence (CL) analysis. Q1 of detrital origin as suggested by its typical morphology with monocrystal structure, large grain‐size, subrounded to angular outlines, and clear edges. This is further supported by the occurrence of medium luminescence under cathodoluminescence and medium intensity of P1 and P2 and high intensity P3 according to CL images. Q2 accounts for more than 90% of quartz and exhibits cryptocrystalline texture, an irregular shape, blurring edges, and low luminescence, and its CL images show low intensity P1, low intensity P2, and high intensity P3. Q3 have the morphologies of siliceous organisms, for example, sponge spicules, radiolaria, and foraminifera. Q2 and Q3 belong to authigenic quartz derived from siliceous organisms. Th/U and V/Cr indicate black shale from LM1–3 mainly deposited in the dysoxic‐anoxic environment while black shale from LM4–5 deposited in the oxic environment. Authigenic quartz‐rich shales from LM1–3 were speculated to be the best shale gas reservoirs characterized by high TOC content, high gas content, and with negligible amount of detrital quartz. Compared with shale from LM1–3, black shale from LM4–5 usually have relatively high detrital quartz content and low TOC content and gas content. Considering the abundant interparticle pore space, the detrital quartz‐rich shale interbedded within the black shale from LM4–5, could also become good shale gas reservoirs if sufficient gas supply is guaranteed.

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Section: Discussionmentioning

confidence: 99%

Source analysis of quartz from the Upper Ordovician and Lower Silurian black shale and its effects on shale gas reservoir in the southern Sichuan Basin and its periphery, China

Han

Jiang

et al. 2018

Geological Journal

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“…Currently, China has performed shale gas exploration in various shales (Yang, Liang, Zhang, ZaixingJiang, & Tang, ) and has a breakthrough in the Longmaxi shale and Niutitang shale in Sichuan Basin (Liang et al, ). By the end of Year 2017, shale gas production has been up to 10 billion cubic in the Longmaxi shale.…”

Section: Discussionmentioning

confidence: 99%

“…By the end of Year 2017, shale gas production has been up to 10 billion cubic in the Longmaxi shale. Compared to the Longmaxi shale, the Niutitang shale is characterized by higher thermal maturity (Ro up to 4%), favourable burial depth, TOC content, and porosity, although smaller than that of Longmaxi shale (Liang et al, ; Yang et al, ). Compared with major gas shale in the United States, the Niutitang shale has relative low present TOC content, because of the high thermal maturity as mentioned above.…”

Section: Discussionmentioning

confidence: 99%

“…Basin (Liang et al, 2017). By the end of Year 2017, shale gas production has been up to 10 billion cubic in the Longmaxi shale.…”

Section: Favourable Sedimentary Environmentmentioning

confidence: 99%

“…With constantly increasing energy demands and the scarcity of conventional oil and gas, unconventional oil and gas, particularly shale oil and gas, have become an important exploration target around the world (Liang, Cao, Jiang, Wu, & Song, ; Liang et al, ; Montgomery, Jarvie, Bowker, & Pollastro, ; Scott & Glasspool, ). Shale gas is essentially continuous‐type biogenic, thermogenic, or combined biogenic–thermogenic gas (Ross & Bustin, ), and shale gas systems are characterized by widespread gas saturation, subtle trapping mechanisms, seals of variable lithology, and relatively short hydrocarbon migration distances (Curtis, ; Jarvie, Hill, & Ruble, ).…”

Section: Introductionmentioning

confidence: 99%

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Shale reservoir characterization and control factors on gas accumulation of the Lower Cambrian Niutitang shale, Sichuan Basin, South China

Liang

Jiang

et al. 2018

Geological Journal

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The Lower Cambrian Niutitang shale is reported to be the oldest strata for large‐scale shale gas reserves. Based on outcrop observations and laboratory analyses, this study used a comprehensive approach that integrated sedimentology, mineralogy, petrology, organic geochemistry, and reservoir geology to estimate the prospects for exploring for shale gas in the Lower Cambrian Niutitang Formation, southern China. Whole rock and clay mineral X‐ray diffraction, scanning electron microscope (SEM) observations, and petro‐physical property measurements indicate that the Niutitang shale is dominated by quartz and clay minerals with minor amounts of plagioclase, potassium feldspar, calcite, dolomite, and pyrite. The organic matter in the Niutitang shale is dominated by type‐1 kerogen, with TOC levels ranging from 1.35% to 14.3% (average 4.46%) and Ro values ranging from 1.86% to 4.18% (average 2.79%). The three primary types of pores in the shale are organic pores, microfractures, and micropores. The micropores are primarily found in the clay mineral crystals and pyrite, and the microfractures are found along the boundaries of quartz grains. Most of the pore diameters are less than 20 nm, mainly concentrate at about 10 nm, which is consistent with that the organic pores act as the main storage space. The pore volume and gas content are strongly controlled by the mineral composition and lithofacies, and TOC content. The factors favouring shale gas accumulation of the Niutitang shale in the study area include (1) an effective thickness and widespread distribution, (2) a high organic carbon content and appropriate organic matter maturity, and (3) a favourable depositional environment.

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Tracing forming mechanism of the sparry calcite growth in the lacustrine shale of east China: A glimpse into the role of organic matter in calcite transformation

et al. 2022

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The formation of sparry calcite is very common in fine‐grained sedimentary rocks worldwide. Sparry calcite is formed from the diagenetic calcite crystals having a grain size > 50 μm. It is also widely distributed in the Es3x shale of the Eocene Shahejie Formation in the Zhanhua Depression, Bohai Bay Basin. The detailed investigations of the Es3x shale show that the sparite crystals start appearing at a burial depth > 3,000 m and the total organic carbon content (TOC) is >3 wt%. It indicates that the sparry calcite formed at high depths and in the most organic‐rich intervals of the studied shale. The presence of organic matter (OM) laminae parallel to the sparry calcite laminae, and sparry calcite along the edges of the OM show a direct physical relationship between sparry calcite and OM. It suggests that the diagenetic system was not influenced by hydrothermal fluids and only the OM is possibly responsible for the formation of sparry calcite in the studied shale. Sparry calcite forms in the thermally mature oil window, and oil generation in the Es3x shale causes the dissolution of micrite, providing the ions source for sparry calcite formation. Therefore, the geothermal gradient, as well as oil generation and kerogen maturation, are responsible for sparry calcite growth in the studied shale. The proposed model shows that the sparry calcite can form in the pores formed by elastic deformation as well as in the microfractures in the study area. In laminated shale, sparry calcite followed three stages of its formation, including (a) formation of laterally discrete calcite crystals, (b) lateral intergrowth of equant calcite crystals and (c) lateral intergrowth of fibrous calcite. Likewise, the genesis of sparry calcite in the non‐laminated shale also followed the same three phases; however, elastic deformation played a dominant and an important role in this variety of shale. Based on the detailed interpretations, we suggest that the OM, microfractures and elastic deformation act as major contributors in the formation and maturation of sparry calcite. We expect that this study also highlights the growth mechanism and maturation of sparry calcite in the Zhanhua Depression as well as other similar rift‐related basins around the globe.

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Shale oil potential of lacustrine black shale in the Eocene Dongying depression: Implications for geochemistry and reservoir characteristics

Cited by 89 publications

References 44 publications

Source analysis of quartz from the Upper Ordovician and Lower Silurian black shale and its effects on shale gas reservoir in the southern Sichuan Basin and its periphery, China

Source analysis of quartz from the Upper Ordovician and Lower Silurian black shale and its effects on shale gas reservoir in the southern Sichuan Basin and its periphery, China

Shale reservoir characterization and control factors on gas accumulation of the Lower Cambrian Niutitang shale, Sichuan Basin, South China

Tracing forming mechanism of the sparry calcite growth in the lacustrine shale of east China: A glimpse into the role of organic matter in calcite transformation

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