Graptolites as fossil geo-thermometers and source material of hydrocarbons: An overview of four decades of progress

Luo, Qingyong; Goodarzi, Fariborz; Zhong, Ningning; Wang, Ye; Qiu, Nansheng; Skovsted, Christian B.; Suchý, Václav; Schovsbo, Niels H.; Morga, R.; Xu, Ying; Hao, Jingyue; Liu, Anji; Wu, Jin; Cao, Weixun; Xu, Mengque; Wu, Jia

doi:10.1016/j.earscirev.2019.103000

Cited by 77 publications

(52 citation statements)

References 174 publications

(570 reference statements)

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“…Thus, their arrangement may intensify the permeability anisotropy of shale [20]. Furthermore, studies also indicated that some types of OM grains without organic pores might still exhibit anisotropy in their inner structure due to their biogenetic texture [21], which may also affect the anisotropy of shale if they were directionally arranged.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Organic Matter Orientation Characteristics of Terrestrial and Marine Shale in China

Liu

Shen

et al. 2021

Geofluids

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As an essential component in shale, OM (organic matter) grains and their arrangements may play essential roles in affecting the anisotropy of the reservoir. However, OM grains are commonly treated as an evenly distributed isotropic medium in current studies, and few works have been done to investigate their detailed arrangement characteristics. In this study, terrestrial and marine shale samples were collected from three different shale plays in China, and the arrangement characteristics of OM grains in each sample were investigated by SEM (scanning electron microscope) image analysis. The results indicate that OM grains in shale are not evenly distributed in isotropic medium, and their directional alignment is pervasive in both marine and terrestrial shale. OM grains in shale tend to subparallel to the bedding section, and their orientation degree and controlling factors differ among different shales. OM grains in samples from terrestrial C-7(Chang-7 Formation) exhibit the strongest directionality in their arrangement, and OM grains in samples from marine LMX (Longmaxi Formation) shale in the Fuling area also exhibit strong directional alignment. While in samples from marine LMX shale in the Baojing area, their directional alignment is much weaker. Shales with high clay content, high TOC (total organic carbon), low thermal maturity, and flat reservoir structure get more OM grains parallel to the bedding section. The biogenetic texture of graptolite in marine LMX shale is the dominating factor leading to the strong directional alignment of the OM grains. However, syncline structure may disorganize the preformed directional alignment and weaken the directionality of the OM grains, which results in the OM arrangement difference between LMX samples from Fuling and Baojing. While the compaction of the layered clay particles is the dominating mechanism leading to the strong directional alignment of the OM grains in terrestrial shale samples from C-7.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Organic Matter Orientation Characteristics of Terrestrial and Marine Shale in China

Liu

Shen

et al. 2021

Geofluids

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“…For Lower Paleozoic and Precambrian shales, solid bitumen reflectance (BR o ) and/or graptolite reflectance (GR o ) are commonly applied as maturity indicators owing to the unavailability of vitrinite reflectance (VR o ) (Bertrand and Malo, 2001;Valentine et al, 2014;Sanei et al, 2015;Luo et al, 2017). However, the two macerals suitable for reflectance measurement do not always occur in these shales (Petersen et al, 2013), and their measured reflectance values do not always accurately reflect the maturity, being restricted by their origin, size and optical anisotropy (Schoenherr et al, 2007;Suárez-Ruiz et al, 2012;Sanei et al, 2015;Luo et al, 2019). Effective maturity indicators of Lower Paleozoic and Precambrian marine shales are still in process of development (Caricchi et al, 2016;Luo et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…However, the two macerals suitable for reflectance measurement do not always occur in these shales (Petersen et al, 2013), and their measured reflectance values do not always accurately reflect the maturity, being restricted by their origin, size and optical anisotropy (Schoenherr et al, 2007;Suárez-Ruiz et al, 2012;Sanei et al, 2015;Luo et al, 2019). Effective maturity indicators of Lower Paleozoic and Precambrian marine shales are still in process of development (Caricchi et al, 2016;Luo et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Thermal maturation as revealed by micro-Raman spectroscopy of mineral-organic aggregation (MOA) in marine shales with high and over maturities

Xiao

Zhou

Cheng

et al. 2020

Sci. China Earth Sci.

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Laser Raman spectroscopy of organic matter in coals and sedimentary rocks has been increasingly investigated to assess thermal maturity. Pure organic matter such as vitrinite and solid bitumen, as well as isolated kerogen are definitely selected for this purpose, but there has been no systematic report on the Raman spectral parameters directly based on mineral-organic aggregations (MOA) in shales. In this paper, the Raman spectral characteristics and parameters of MOA in two sets of marine shale samples from southern China with either different TOC contents (TOC=0.10-4.59%) or different maturities (BR o =1.71-4.57%) were investigated. It was found that the Raman technique is very sensitive to the organic matter in MOA. As the TOC content of the shales reaches about 0.60%, perfect Raman spectra with D and G bands derived from organic matter in MOA were obtained, and the Raman parameters of MOA are in good agreement with those of its associated solid bitumen, and can indicate the thermal maturity just like those of solid bitumen. Using the Raman parameters of MOA is a potential alternative way to estimate maturity levels of high and over mature shales, especially those lower Paleozoic and Precambrian shales that lack macerals suitable for reflectance or Raman measurements.

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“…A lot of methods are widely used to characterize pores in shales, including field emission scanning electron microscopy (FE-SEM), atomic-force microscopy (AFM), computed tomography (CT) scanning, nuclear magnetic resonance (NMR), He-pycnometry, low-temperature gas adsorption (CO 2 and N 2 ), mercury injection capillary pressure (MICP) and small-angle neutron/X-ray scattering (Loucks et al, 2009;Sisk et al, 2010;Sondergeld et al, 2010;Javadpour et al, 2012;Tinni et al, 2014;Wang et al, 2015a;Han et al, 2016aHan et al, , 2020bSun et al, 2017Sun et al, , 2020Luo et al, 2020). Porosity and pore-size distribution obtained from different methods may vary due to different principles and pore-size range detection (Bertier et al, 2016).…”

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confidence: 99%

Pore Characteristics and Factors Controlling Lacustrine Shales from the Upper Cretaceous Qingshankou Formation of the Songliao Basin, Northeast China: A Study Combining SEM, Low‐temperature Gas Adsorption and MICP Experiments

Han

Dai

Zhong

et al. 2021

Acta Geologica Sinica (Eng)

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Cao et al., 2019) due to the commercial production of shale gas and shale oil in North America. Oil and gas mainly occur in the pores of shales (Curtis, 2002). In shales, there are three types of pores: interparticle pores, intraparticle pores and organic matter (OM) pores (Loucks et al., 2012). The abundance of the three types of pores in shales is mainly controlled by the mineralogical composition and organic matter content (e. g.

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Graptolites as fossil geo-thermometers and source material of hydrocarbons: An overview of four decades of progress

Cited by 77 publications

References 174 publications

Experimental Investigation on Organic Matter Orientation Characteristics of Terrestrial and Marine Shale in China

Experimental Investigation on Organic Matter Orientation Characteristics of Terrestrial and Marine Shale in China

Thermal maturation as revealed by micro-Raman spectroscopy of mineral-organic aggregation (MOA) in marine shales with high and over maturities

Pore Characteristics and Factors Controlling Lacustrine Shales from the Upper Cretaceous Qingshankou Formation of the Songliao Basin, Northeast China: A Study Combining SEM, Low‐temperature Gas Adsorption and MICP Experiments

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