Impact of thermal maturity on the concomitant evolution of the ultrafine structure and porosity of marine mudstones organic matter; contributions of electronic imaging and new spectroscopic investigations

Cavelan, Amélie; Boussafir, Mohammed; Mathieu, Nathalie; Laggoun‐Défarge, Fatima

doi:10.1016/j.coal.2020.103622

Cited by 13 publications

(3 citation statements)

References 76 publications

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“…OM Maturity. The OM maturity can control gas compositions of shale gas reservoirs and affect their gas-bearing property [23,47,[139][140][141][142]. The OM maturity can also affect pore characteristics of shales, especially the generation and evolution of organic pores, thus influencing reservoir property [130,131,143,144].…”

Section: Factors Controlling Porosity and Gas Content Of The Lower Ca...mentioning

confidence: 99%

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Gao

Xiao

et al. 2022

Geofluids

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The Lower Cambrian shales are widely developed in southern China, with greater thicknesses and higher TOC contents. Although the shale gas resource potential has been suggested to be huge, the shale gas exploration and development is not satisfactory. At present, the gas-bearing property evaluation of the Lower Cambrian shale is still a hot spot of concern. According to previous works, this paper systematically summarizes the gas-bearing characteristics and controlling factors of the Lower Cambrian shales in southern China. The buried depth of Lower Cambrian shales mainly ranges from 3000 m to 6000 m, and the thickness of organic-rich shale intervals ( TOC > 2 % ) varies from 20 m to 300 m. The TOC content and EqVRo value are generally up to 2%-10% and 2.5%-6.0%, respectively. The gas content of the Lower Cambrian shales in the Weiyuan-Qianwei block of the Sichuan Basin and the western Hubei area generally exceeds 2 m3/t, and gas composition is dominated by CH4. In southeastern Chongqing, northwestern Hunan, and northern Guizhou areas, the gas content of the Lower Cambrian shales is generally <2 m3/t, and the N2 content is generally >60%. In the Lower Yangtze region, the Lower Cambrian shale reservoirs basically contain no gas. Higher maturity, lower porosity, and less-no organic pores are suggested to be responsible for low gas contents and/or the predominate of N2 in shale gas reservoirs. Strong tectonic deformation is an important factor leading to the massive gas loss from shale reservoirs, thus resulting in no gas or only a small amount of N2 in the Lower Cambrian shales. In a word, the Lower Cambrian shale gas plays with low maturity and relatively stable tectonic condition, especially deep-ultradeep zones, may be the favorable targets for shale gas exploration.

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Section: Factors Controlling Porosity and Gas Content Of The Lower Ca...mentioning

confidence: 99%

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Gao

Xiao

et al. 2022

Geofluids

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“…In recent years, a great number of works that aimed to better understand the physicalchemical processes affecting the OM in source rocks, the porosity, and the storage capacity of unconventional reservoirs were based on laboratory thermal maturation experiments (e.g. Cavelan et al, 2020bCavelan et al, , 2020cCavelan et al, , 2019aGafurova et al, 2021;Guo et al, 2017;Ko et al, 2018Ko et al, , 2016Song et al, 2020;T. Wang et al, 2021;Wang et al, 2020;Wu et al, 2018;Xu et al, 2021;Yang et al, 2018).…”

Section: General Implicationsmentioning

confidence: 99%

Does grain size influence hydrocarbons generation and mesoporosity during artificial thermal maturation of an organic-rich mudstone?

Cavelan

Boussafir

2022

Journal of Petroleum Science and Engineering

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“…Many closed and semi-closed pyrolysis experiments have been performed in recent years on immature and weakly mature shale samples to uncover pore evolution in these lithologies. These studies have shown that the porosity of the shale decreases during maturation due to the covering and filling effects of bitumen and oil hydrocarbons at the oil-window stage, and OPs increase due to the cracking of OM. ,,, Unfortunately, numerous fruits are focused on those with a thermal maturation less than 3.0% R o , while the pore evolution of shales at highly mature to overmature stages is still insufficient in laboratory simulations, mainly due to analytical temperature limitations of these instruments, as the maximum pyrolysis temperature is generally lower than 600 °C. Therefore, pore evolution mechanisms of shales at R o > 3.0% are ambiguous at present.…”

Section: Introductionmentioning

confidence: 99%

Relationships between Organic Structure Carbonization and Organic Pore Destruction at the Overmatured Stage: Implications for the Fate of Organic Pores in Marine Shales

Song

Tuo

2022

Energy Fuels

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To reveal the relationships between kerogen structure variations and the evolution of organic pore (OP) characteristics in overmatured shales, we conducted total organic carbon (TOC) analysis, Raman spectroscopy, Fourier-transform infrared spectroscopy, gas (N2 and CO2) adsorption tests, and field-emission scanning electron microscopy on a high-maturity Silurian shale from South China, alongside its solid residues (kerogen) produced from semi-closed pyrolysis. The results showed that the TOC value of solid residues increased significantly during heating, and the chemical structure of organic matter (OM) in kerogen samples abruptly changed at 500 °C (3.49% R mc), which is interpreted as recording intense carbonization of OM. These variations in the OM structure lead to reductions in the pore volume and specific surface area of bulk-rock and kerogen samples at 450–500 °C. Oval, elliptical, and spongy OPs gradually became interconnected and coalesced into organic microcracks. The diameter of newly formed microcracks increased with the degree of graphitization, exceeding 200 nm at temperatures above 500 °C. During this process, the rock matrix changed from being relatively compact to being relatively loose. Cambrian shale located in South China has irregular and arcuate OP boundaries under normal geological conditions, and the high thermal maturity of this shale may indicate that the coupling of OM carbonization and mechanical compaction is responsible for its poor development of OPs. Here, we present a schematic model for pore evolution in type-I/II marine shales that encompasses the entire hydrocarbon generation stage, which is based on semi-closed pyrolysis analyses. The model is examined using the collected and compilated data for many type-I/II marine shales around the world. These data show that naturally matured marine shales acquire a maximum porosity at 2.5% < R o < 3.0%. This study provides an important guide for marine shale gas exploration and development in China.

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Impact of thermal maturity on the concomitant evolution of the ultrafine structure and porosity of marine mudstones organic matter; contributions of electronic imaging and new spectroscopic investigations

Abstract: Impact of thermal maturity on the concomitant evolution of the ultrafine structure and porosity of marine mudstones organic matter; contributions of electronic imaging and new spectroscopic investigations

Cited by 13 publications

References 76 publications

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Does grain size influence hydrocarbons generation and mesoporosity during artificial thermal maturation of an organic-rich mudstone?

Relationships between Organic Structure Carbonization and Organic Pore Destruction at the Overmatured Stage: Implications for the Fate of Organic Pores in Marine Shales

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