Pore and pore network evolution of Upper Cretaceous Boquillas (Eagle Ford–equivalent) mudrocks: Results from gold tube pyrolysis experiments

Ko, Lucy T.; Loucks, Robert G.; Zhang, Tongwei; Ruppel, Stephen C.; Shao, Deyong

doi:10.1306/04151615092

Cited by 166 publications

(137 citation statements)

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“…Organic matter pores are considered to be influenced by organic matter type and thermal maturation (Ko et al, 2016). The first member of the Qingshankou Formation contains type II organic matter, which is mainly sourced from algal-microbial mats (i.e., lamalginite; Jia et al, 2013a).…”

Section: Shale Oil Reservoirmentioning

confidence: 99%

Lithofacies and depositional setting of a highly prospective lacustrine shale oil succession from the Upper Cretaceous Qingshankou Formation in the Gulong sag, northern Songliao Basin, northeast China

et al. 2019

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The lacustrine shale of the Upper Cretaceous Qingshankou Formation is the principal prospective unconventional target lithology, acting as source, reservoir, and seal. Lithofacies and associated storage capacity are two significant factors in shale oil prospectivity. This paper describes an investigation of the lower Qingshankou Formation lacustrine shale based on detailed description and analysis of cores, shale lithofacies characteristics, depositional setting, and stacking patterns.Seven lithofacies are recognized based on organic matter content, sedimentary structure, and mineralogy, all exhibiting rapid vertical and lateral changes controlled by the depositional setting and basin evolution. An overall trend from shallow-water to deep-water depositional environments is interpreted from the characteristics of the infilling sequences, characterized by increasing total organic carbon (TOC) and total clay content and decreasing layer thickness (i.e., from bedded to laminated then to massive sedimentary structures). Periods of deposition during shallowing cycles show a reverse trend in the sedimentary characteristics described above. The sedimentary rocks in the studied interval show three complete short-term cycles, each one containing progressive and regressive system tracts.

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Section: Shale Oil Reservoirmentioning

confidence: 99%

Lithofacies and depositional setting of a highly prospective lacustrine shale oil succession from the Upper Cretaceous Qingshankou Formation in the Gulong sag, northern Songliao Basin, northeast China

et al. 2019

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“…OM-hosted pores inherited from the original structure of cellulose, lignaceous debris or between adjacent cells of colonial algae are sometimes present (Löhr et al, 2015;Reed, 2017), but pores are rarely observed in type II OM in the immature stage (Bernard et al, 2012a;Cavelan et al, 2019;Katz and Arango, 2018;Kuila et al, 2014). However, pores are frequently observed in thermally mature mudstones (Bernard et al, 2012b;Cavelan et al, 2019;Curtis et al, 2012;Katz and Arango, 2018;Ko et al, 2018Ko et al, , 2016Kuila et al, 2014;Loucks et al, 2012Loucks et al, , 2009. It has been well-documented that changes in the abundance, size and shape of the OM pores during burial appears to be mainly stimulated by oil and primary and/or secondary gas generation from oil-prone kerogen (Bernard et al, 2012a, b;Cardott et al, 2015;Chalmers and Bustin, 2008;Chen and Xiao, 2014;Curtis et al, 2012;Katz and Arango, 2018;Ko et al, 2018Ko et al, , 2016Loucks et al, 2012;Mastalerz et al, 2013;Milliken et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effect of organic matter composition on source rock porosity during confined anhydrous thermal maturation: Example of Kimmeridge-clay mudstones

Cavelan

Boussafir

Milbeau

et al. 2019

International Journal of Coal Geology

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To investigate how slight differences in the total particulate organic matter (OM) assemblage and maceral types of marine mudstones influence the development and the evolution of OM porosity throughout the same formation, laboratory gold-tube anhydrous confined thermal maturation was applied on low-mature organic-rich marine Kimmeridge clay mudstones (Yorkshire, UK). Organic petrography (palynofacies and maceral analysis), SEM observations, global and molecular geochemical characterization and low-pressure nitrogen adsorption measurements were performed to examine, to our knowledge for the first time, the role of the OM composition and properties on the evolution of porosity during thermal maturation. Evidence from organic petrography and geochemical analyses showed that organic-rich Kimmeridge clay samples containing a higher relative proportion of brown amorphous organic matter (AOM), known to be derived essentially from the cell walls of microalgae, exhibit a different pore evolution compared to samples containing a higher proportion of oil-prone orange AOM derived primarily from preservation by natural sulfurization of phytoplanktonic organic components naturally rich in lipidic compounds. OM conversion of orange AOM-rich samples has led to the production of higher amounts of low viscous oil and abundant gaseous hydrocarbon that are more 2 favorable to the formation of abundant but small OM micropores and mesopores in the condensate/wet gas zone and less abundant large modified mineral pores in the dry gas zone. The secondary cracking of the heavier oil produced by brown-AOM-rich OM has led to the formation of a greater quantity of CO2 and an abundant organic-rich residue more favorable to the formation of larger mesopores. Moreover, the more abundant thick laminar bituminite macerals forming a continuous ductile network particularly prone to compaction and the higher amounts of oil/bitumen generated during their conversion may have led to a higher pore collapse after oil/gas generation and migration, responsible for the destruction of part of the secondary pore network observed on some samples. Despite their slightly lower oil-prone potential, brown AOM-rich samples have thus developed larger mesopores during thermal maturation, resulting in higher pore volumes in the dry gas zone. Thus, the ability of marine mudstones to develop pores during maturation do not increase proportionally with the OM oil prone quality. These results show that variations in the individual particulate OM assemblage of a similar type II kerogen can significantly influence the amount of oil and gas generated during thermal maturation throughout the same formation, resulting in different pore evolution models. This reveals the importance of clearly identifying the composition of the original particulate OM assemblage to better predict the amount of bitumen, oil and gas generated during thermal maturation and the associated pore development.

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“…These OM pores are usually considered to be related to hydrocarbon generation and expulsion during the thermal evolution of kerogen 15–17 . Studies performed on shale samples with different thermal maturities 5,7,18,19 indicated that the role of thermal maturity and OM types (kerogens of marine or terrestrial origin, or solid bitumen) in the formation of OM pores is poorly understood but potentially critical 2,5,6,20 . Defining the development of OM pores in shales with different organic matter types, as well as their control on OM pores development is essential for predicting the storage and production ability in the shale gas formation 5 .…”

Section: Introductionmentioning

confidence: 99%

Characteristics of three organic matter pore types in the Wufeng-Longmaxi Shale of the Sichuan Basin, Southwest China

Nie

Jin

Zhang

2018

Sci Rep

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A consensus has been reached through previous studies that organic matter (OM) pores are crucial to porosity in many shale gas reservoirs; however, their origins and types remain controversial. Here, we report the OM pore types hosted in algae, bitumen, graptolite and other fossil fragments in the Wufeng-Longmaxi Formations of the Sichuan Basin, Southwest China. Algae types mainly include multicellular algae, unicellular algae, etc. The OM pores in multicellular algae usually exhibit irregular, bubble-like, spherical and/or elliptical profiles, and their diameters vary between 300 and 800 nm. The shapes of the OM pores in unicellular algae are either irregular or oval, and the pores are hundreds of nanometres in size. The pores associated with solid bitumen are sporadic, isolated and variable in size, ranging from 500 nm to 3 μm. The pores in the graptolite, sponge spicule, radiolarian and other fossil fragments are much smaller and fewer. The pores may only have developed in the surface of the graptolite and bitumen by filling in the biological cavity of the sponge spicule. These new findings provide stronger evidence that multicellular algae are the main hydrocarbon generating organisms of OM pores development.

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Pore and pore network evolution of Upper Cretaceous Boquillas (Eagle Ford–equivalent) mudrocks: Results from gold tube pyrolysis experiments

Cited by 166 publications

References 45 publications

Lithofacies and depositional setting of a highly prospective lacustrine shale oil succession from the Upper Cretaceous Qingshankou Formation in the Gulong sag, northern Songliao Basin, northeast China

Lithofacies and depositional setting of a highly prospective lacustrine shale oil succession from the Upper Cretaceous Qingshankou Formation in the Gulong sag, northern Songliao Basin, northeast China

Effect of organic matter composition on source rock porosity during confined anhydrous thermal maturation: Example of Kimmeridge-clay mudstones

Characteristics of three organic matter pore types in the Wufeng-Longmaxi Shale of the Sichuan Basin, Southwest China

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