Differences of marine and transitional shales in the case of dominant pore types and exploration strategies, in China

Li, Xin; Jiang, Zhenxue; Wang, Shuai; Wu, Fan; Miao, Yanying; Wang, Xingmeng; Wang, Haixue; Li, Xin

doi:10.1016/j.jngse.2022.104628

Cited by 6 publications

(6 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The main storage space of shale gas is the micro-/nano-pores, which mainly consist of organic pores, intergranular pores, and intragranular pores. − The pore characteristics are closely related to the sedimentary environments. Organic pores formed by hydrocarbon generation are the main gas occurrence space for marine shale, which has been verified in many studies. − However, organic pores in coal measure shale and terrestrial shale are poorly developed. Cao et al believed that compared with marine shale, coal measure shale has lower maturity and fewer organic pores, resulting in a negative correlation between the porosity and total organic carbon (TOC).…”

Section: Introductionmentioning

confidence: 89%

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Zhang

Kang

et al. 2022

Energy Fuels

View full text Add to dashboard Cite

Substantial coal measure gas is reserved in the Upper Permian shale in western Guizhou, China, but the mechanism of gas generation and enrichment remains unclear. In this study, rock-eval pyrolysis, stable carbon isotope, and low-temperature N2/CO2 adsorption (LN2/CO2A) experiments were conducted on coal measure shale collected from western Guizhou. The geochemical composition and pore morphology were clarified, and the shale gas generation and storage characteristics were ultimately revealed. The results show that the total organic carbon (TOC) contents of most samples exceed 2%, indicating a high organic matter (OM) abundance. The average R o and T max are 2.89% and 576 °C, respectively, corresponding to the overmature stage, leading to the poor current hydrocarbon generation potential. Unlike marine shale with dense organic pores, these pores are generally poorly developed and heterogeneous in the samples. Densely distributed microfractures are favorable methane migration channels. The pores are dominated by mesopores, with an average pore volume (PV) proportion of 53.55%, while the specific surface area (SSA) is mainly contributed by micropores. The LCO2A-SSA and LCO2A-PV show a positive correlation with the TOC, T max, and S1, but the LN2A-SSA and LN2A-PV are poorly correlated with these parameters, indicating that micropores are mainly derived from organic pores and that hydrocarbons generated by OM pyrolysis are mainly reserved in micropores. When δ13COM shows a negative anomaly, R o, T max, and S1 all show a negative drift in the vertical sequence, suggesting that the chemical parameters are closely related during thermal maturation. Accompanied by hydrocarbon generation, 12CH4 is preferentially separated from the OM, resulting in a higher δ13COM. Meanwhile, the generated methane is mainly reserved in the form of adsorption, and the micropores/mesopores provide a favorable place for shale gas storage.

show abstract

Section: Introductionmentioning

confidence: 89%

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Zhang

Kang

et al. 2022

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…The division schemes of shale lithofacies were proposed based on TOC content and mineral composition in previous studies: 1) according to TOC content, shale was divided into 3 types and they are: organic-rich shale (TOC content:≥2%), organic-bearing shale (TOC content: 1-2%), and organic-lean shale (TOC content: 0-1%); 2) according to mineral composition, shale was divided into 4 types and they are: calcareous shale (carbonate minerals ≥50%), clayey shale (clay minerals ≥50%), siliceous shale (siliceous minerals ≥50%), mixed shale (siliceous minerals, clay minerals and carbonate minerals are all less than 50%) (Clarkson et al, 2013;Daigle et al, 2017;Zhang et al, 2019a;Li et al, 2022b;Zhang et al, 2022c). In combination with the two division schemes, there appear 3×4=12 types of lithofacies.…”

Section: Lithofacies Division Of Shalementioning

confidence: 99%

Study on characteristics of oil and gas occurrence and reservoir space of medium-high maturity continental shale—A case study of middle jurassic lianggaoshan formation in fuling block, southeast of sichuan basin, south China

et al. 2022

View full text Add to dashboard Cite

Possessed of easy access to development and fair economic benefits, medium-high maturity continental shale oil and gas have become the focus of shale oil and gas study in the future. Shale oil and gas mainly occur in pores, but studies on the pore characteristics of shale oil and gas occurrence are by no means sufficient. Focused on shale from the Middle Jurassic Lianggaoshan Formation in Well TYX, Fuling block, southeast of Sichuan Basin where a breakthrough in shale oil and gas exploration was recently achieved, this study selects core samples and conducts a series of analyses, including vitrinite reflectance analysis, kerogen microscopic examination experiment, total organic carbon (TOC) content analysis, mineral composition analysis, gas content measurement, isothermal adsorption experiment, S1 content analysis, and others. The analyses are to identify the pore characteristics of the continental medium and high maturity shale oil and gas by virtue of scanning electron microscope (SEM) with Ar-ion milling and the image processing software ImageJ. The conclusions are drawn as follows: in terms of lithofacies, medium-high maturity continental shale oil and gas mainly occur in organic-rich clay shale and organic-rich mixed shale; with regard to material composition, shale oil and gas mainly occur in organic matter, illite-smectite mixed layers and illite. Shale adsorbed gas content accounts for at most 40% of the total shale gas content and shale free gas content takes up at least 60% of the total shale gas content. Pores of solid bitumen, solid bitumen-clay mineral complex mass, clay minerals, structured vitrinite, and funginite are mostly developed in shale. Among them, the first three types of pores are the main reservoir space in shale considering their large number, good roundness, medium pore diameter, fairly good roundness of pore edges, and the complex shapes which altogether contribute to the large surface porosity.

show abstract

“…Scholars have also worked on comparing the nanopore properties of transitional and marine shales. − Yang et al , investigated the morphology of organic-associated pores and nanoporosity for marine, transitional, and lacustrine shale from different basins in China. Their results revealed that marine shale is dominated by organic pores, while lacustrine and transitional shale give priority to clay-related pores.…”

Section: Introductionmentioning

confidence: 99%

“…Wu et al 30 compared the pore characteristics of marine and transitional shales from the lower Yangtze block and proposed that organic pores are poorly developed in both types of shale due to their low maturity. Li et al 26 conducted a comparative study on the nanopore characteristics of marine shale from the Sichuan Basin and transitional shale from the middle Yangtze Block. Their findings demonstrated that organic nanopores predominate in marine shale while mineral-hosted nanopores predominate in transitional shale.…”

Section: Introductionmentioning

confidence: 99%

“…Oil-prone OM (type I) is usually pore-rich for its transformation to oil and gas during thermal maturation. In contrast, pore within terrigenous OM (type III) is usually limited due to its low hydrocarbon generation potential. − Shale OM-hosted nanopores follow parabolic patterns as maturity increase, initially growing until R 0 2.5–3.5% and then decreasing after that. − Clay-associated pores are primarily mesopores and are commonly seen in illite and/or smectite aggregates in shale. − …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparative Study on the Primary Control Factors of Nanopores in Transitional and Deep Marine Shale in the Southeastern Sichuan Basin, China

Liu

Meng

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

The deep marine shale from the Silurian Longmaxi Formation and transitional shale from the Permian Longtan Formation in the Sichuan Basin are two promising targets for shale gas exploration in China. In this study, nanopore characteristics for deep marine and transitional shale samples collected from the same well in the southeastern Sichuan Basin are investigated and compared via field emission scanning electron microscopy imaging, low-pressure gas adsorption, total organic carbon measurement, and X-ray diffraction. Results show that clay-related pores are well developed, pores within organic matter (OM) are rare, and shrinkage cracks along the OM-edge are widely prevalent in transitional shales. The deep marine shale is rich in bubble-like OM pores. The transitional shale has a larger pore volume but a lower specific surface area compared to the deep marine shale. The nanoporosity of the transitional shales is primarily controlled by clay and OM content. In deep marine shale, OM is the primary contributor to nanoporosity. Higher nanoporosity in the deep marine shales than in the middle-shallow ones was observed in this study. This occurrence is attributed to the high fluid pressure and the resulting superior preservation conditions for nanopores in deep marine shale formations.

show abstract

Differences of marine and transitional shales in the case of dominant pore types and exploration strategies, in China

Cited by 6 publications

References 41 publications

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Study on characteristics of oil and gas occurrence and reservoir space of medium-high maturity continental shale—A case study of middle jurassic lianggaoshan formation in fuling block, southeast of sichuan basin, south China

Comparative Study on the Primary Control Factors of Nanopores in Transitional and Deep Marine Shale in the Southeastern Sichuan Basin, China

Contact Info

Product

Resources

About