Skip to main content
SpringerLink
Log in

The pore structure and fractal characteristics of shales with low thermal maturity from the Yuqia Coalfield, northern Qaidam Basin, northwestern China

  • Research Article
  • Published:
Frontiers of Earth Science Aims and scope Submit manuscript

Abstract

The continental shales from the Middle Jurassic Shimengou Formation of the northern Qaidam Basin, northwestern China, have been investigated in recent years because of their shale gas potential. In this study, a total of twenty-two shale samples were collected from the YQ-1 borehole in the Yuqia Coalfield, northern Qaidam Basin. The total organic carbon (TOC) contents, pore structure parameters, and fractal characteristics of the samples were investigated using TOC analysis, low-temperature nitrogen adsorption experiments, and fractal analysis. The results show that the average pore size of the Shimengou shales varied from 8.149 nm to 20.635 nm with a mean value of 10.74 nm, which is considered mesopore-sized. The pores of the shales are mainly inkbottle- and slit-shaped. The sedimentary environment plays an essential role in controlling the TOC contents of the low maturity shales, with the TOC values of shales from deep to semi-deep lake facies (mean: 5.23%) being notably higher than those of the shore-shallow lake facies (mean: 0.65%). The fractal dimensions range from 2.4639 to 2.6857 with a mean of 2.6122, higher than those of marine shales, which indicates that the pore surface was rougher and the pore structure more complex in these continental shales. The fractal dimensions increase with increasing total pore volume and total specific surface area, and with decreasing average pore size. With increasing TOC contents in shales, the fractal dimensions increase first and then decrease, with the highest value occurring at 2% of TOC content, which is in accordance with the trends between the TOC and both total specific surface area and total pore volume. The pore structure complexity and pore surface roughness of these low-maturity shales would be controlled by the combined effects of both sedimentary environments and the TOC contents.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Barrett E P, Joyner L G, Halenda P P (1951). The determination of pore volume and area distribution in porous substances. I. Computations from nitrogen isotherms. J Am Chem Soc, 73(1): 373–380

    Article  Google Scholar 

  • Bernard S, Horsfield B, Schulz H M, Wirth R, Schreiber A, Sherwood N (2012). Geochemical evolution of organic-rich shales with increasing maturity: a STXM and TEM study of the Posidonia Shale (Lower Toarcian, northern Germany). Mar Pet Geol, 31(1): 70–89

    Article  Google Scholar 

  • Bowker K A (2007). Barnett shale gas production, Fort Worth Basin: issues and discussion. AAPG Bull, 91(4): 523–533

    Article  Google Scholar 

  • Brunauer S, Emmett P H, Teller E (1938). Adsorption of gases in multimolecular layers. J Am Chem Soc, 60(2): 309–319

    Article  Google Scholar 

  • Cao T T, Song Z G, Luo H Y, Liu G X (2015). The differences of microscopic pore structure characteristics of coal, oil shale and shales and their storage mechanisms. Natural Gas Geoscience, 26(11): 2208–2218 (in Chinese)

    Google Scholar 

  • Chalmers G R, Bustin R M (2008). Lower Cretaceous gas shales in northeastern British Columbia, Part I: geological controls on methane sorption capacity. Bull Can Pet Geol, 56(1): 1–21

    Article  Google Scholar 

  • Chalmers G R, Bustin R M, Power I M (2012). Characterization of gas shale pore systems by porosimetry, pycnometry, surface area, and field emission scanning electron microscopy/transmission electron microscopy image analyses: examples from the Barnett, Woodford, Haynesville, Marcellus, and Doig units. AAPG Bull, 96(6): 1099–1119

    Article  Google Scholar 

  • Donaldson E C, Kendall R F, Baker B A, Manning F S (1975). Surfacearea measurement of geological matereials. Soc Pet Eng J, 15(02): 111–116

    Article  Google Scholar 

  • Dow W G (1977). Kerogen studies and geological interpretations. J Geochem Explor, 7(2): 79–99

    Article  Google Scholar 

  • Fildani A, Hanson A D, Chen Z Z, Moldowan J D, Graham S A, Arriola P R (2005). Geochemical characteristics of oil and source rocks and implication for petroleum system, Talara basin, northwest Peru. AAPG Bull, 89(11): 1519–1545

    Article  Google Scholar 

  • Gauden P A, Terzyk A P, Rychlicki G (2001). The new correlation between microporosity of strictly microporous activated carbons and fractal dimension on the basis of the Polanyi-Dubinin theory of adsorption. Carbon, 39(2): 267–278

    Article  Google Scholar 

  • Gregg S J, Sing K S W (1982). Adsorption, Surface Area and Porosity (2nd ed). London: Academic Press, 42–55

    Google Scholar 

  • Li A, Ding W L, He J H, Dai P, Yin S, Xie F (2016). Investigation of pore structure and fractal characteristics of organic-rich shale reservoirs: a case study of Lower Cambrian Qiongzhusi Formation in Malong block of eastern Yunnan Province, South China. Mar Pet Geol, 70: 46–57

    Article  Google Scholar 

  • Li M, Shao L Y, Lu J, Spiro B, Wen H J, Li Y H (2014). Sequence stratigraphy and paleogeography of the Middle Jurassic coal measures in the Yuqia Coalfield, northern Qaidam Basin, northwestern China. AAPG Bull, 98(12): 2531–2550

    Article  Google Scholar 

  • Li Y J, Li X J, Wang Y L, Yu Q C (2015). Effects of composition and pore structure on the reservoir gas capacity of Carboniferous shale from Qaidam Basin, China. Mar Pet Geol, 62: 44–57

    Article  Google Scholar 

  • Liang L X, Xiong J, Liu X J (2015). An investigation of the fractal characteristics of the Upper Ordovician Wufeng Formation shale using nitrogen adsorption analysis. J Nat Gas Sci Eng, 27(10): 402–409

    Article  Google Scholar 

  • Liu S X, Zhong J H, Ma Y S, Yin C M, Liu C L, Li Z X, Liu X, Li Y, Liu X G (2015a). Study of microscopic pore structure and adsorption isothermal of carboniferous shale, Eastern Qaidam Basin. Journal of China University of Petroleum, 39(1): 33–42 (in Chinese)

    Google Scholar 

  • Liu X J, Xiong J, Liang L X (2015b). Investigation of pore structure and fractal characteristics of organic-rich Yanchang Formation shale in central China by nitrogen adsorption/desorption analysis. J Nat Gas Sci Eng, 22: 62–72

    Article  Google Scholar 

  • Loucks R G, Reed R M, Ruppel S C, Hammes U (2012). Spectrum of pore types and networks in mudrocks and a descriptive classification for matrix-related mudrock pores. AAPG Bull, 96(6): 1071–1098

    Article  Google Scholar 

  • Luo C, Liu S G, Sun W, Ran B, Wang S Y, Yang D, Bai Z Q, Ye Y C, Zhang X, Deng B (2014). Pore structure characterization of black shale in the Lower Cambrian Niutitang Formation in western Hubei and eastern Chongqing area. Journal of Northeast Petroleum University, 38(2): 8–17 (in Chinese)

    Google Scholar 

  • Micromeritics Instrument Corporation (2012). TriStarII 3020 Operator’s Manual. Georgia: C15–C20

    Google Scholar 

  • Milliken K L, Rudnicki M, Awwiller D N, Zhang T (2013). Organic matter-hosted pore system, Marcellus Formation (Devonian), Pennsylvains. AAPG Bull, 97(2): 177–200

    Article  Google Scholar 

  • Montgomery S L, Jarvie D M, Bowker K A, Pollastro R M (2005). Mississippian Barnett shale, Fort Worth Basin, North-Central Texas: gas-shale play with multi-trillion cubic foot potential. AAPG Bull, 89 (2): 155–175

    Article  Google Scholar 

  • Nakagawa T, Komaki I, Sakawa M, Nishikawa K (2000). Small angle Xray scattering sudy on change of fractal property of Witbank coal with heat treatment. Fuel, 79(11): 1341–1346

    Article  Google Scholar 

  • Pfeifer P, Avnir D (1983). Chemistry in noninteger dimensions between two and three. I. Fractal theory of heterogeneous surfaces. J Chem Phys, 79(7): 3558–3565

    Article  Google Scholar 

  • Pyun S I, Rhee C K (2004). An investigation of fractal characteristics of mesoporous carbon electrodes with various pore structures. Electrochim Acta, 49(24): 4171–4180

    Article  Google Scholar 

  • Qi H, Ma J, Wong P Z (2002). Adsorption isotherms of fractal surfaces. Colloid Surface A, 206(1‒3): 401–407

    Article  Google Scholar 

  • Rigby S P (2005). Predicting surface diffusivities of molecules from equilibrium adsorption isotherms. Colloid Surface A, 262(1‒3): 139–149

    Article  Google Scholar 

  • Shao L Y, Li M, Li Y H, Zhang Y P, Lu J, Zhang W L, Tian Z, Wen H J (2014). Geological characteristics and controlling factors of shale gas in the Jurassic of the northern Qaidam Basin. Earth Sci Front, 21(4): 311–322 (in Chinese)

    Google Scholar 

  • Shao L Y, Liu L, Wen H J, Li Y H, Zhang W L, Li M (2016). Characteristics and influencing factors of nanopores in the Midddle Jurassic Shimengou shale in Well YQ-1 of the northern Qaidam Basin. Earth Sci Front, 23(1): 164–173 (in Chinese)

    Google Scholar 

  • Sing K S W (1982). Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity. Pure Appl Chem, 54(11): 2201–2218

    Article  Google Scholar 

  • Tang X L, Jiang Z X, Li Z, Gao Z Y, Bai Y Q, Zhao S, Feng J (2015). The effect of the variation in material composition on the heterogeneous pore structure of high-maturity shale of the Silurian Longmaxi formation in the southeastern Sichuan Basin, China. J Nat Gas Sci Eng, 23: 464–473

    Article  Google Scholar 

  • Wang M, Xue H T, Tian S S, Wilkins R W T, Wang Z W (2015). Fractal characteristics of Upper Cretaceous lacustrine shale from the Songliao Basin, NE China. Mar Pet Geol, 67: 144–153

    Article  Google Scholar 

  • Wang X Z, Gao S L, Gao C (2014). Geological features of Mesozoic lacustrine shale gas in south of Ordos Basin, NW China. Petrol Explor Develop, 41(3): 326–337

    Article  Google Scholar 

  • Wu J G, Liu D M, Yao Y B (2014). Characteristics and controlling factors of nanopores in shales in Weibei, Ordos Basin. Oil & Gas Geology, 35(4): 542–550 (in Chinese)

    Google Scholar 

  • Xiao Z H, Wang C H, Yang F R, Feng T, Wang Q R, Huang Y R, Chen X Y, Deng Y (2013). Reservoir conditions of shale gas in Lower Cambrian Niutitang Formation, northwestern Hunan. Acta Geol Sin, 87(10): 1612–1623 (in Chinese)

    Google Scholar 

  • Xie H P (1996). A Study for Fractal and Rock Mechanics. Beijing: Science Publishing House, 93–95 (in Chinese)

    Google Scholar 

  • Yang F, Ning Z F, Liu H Q (2014). Fractal characteristics of shales from a shale gas reservoir in the Sichuan Basin, China. Fuel, 115(1): 378–384

    Article  Google Scholar 

  • Yao Y B, Liu D M, Tang D Z, Tang S H, Huang W H (2008). Fractal characterization of adsorption-pores of coals from North China: an investigation on CH4 adsorption capacity of coals. Int J Coal Geol, 73 (1): 27–42

    Article  Google Scholar 

  • Zhang D W, Li Y X, Zhang J C, Qiao D W, Jiang WL, Zhang J F (2012). The Evaluation of Shale Gas Resources and Potential Investigation in China. Beijing: Geology Publishing House, 70–78 (in Chinese)

    Google Scholar 

  • Zhang J C, Jin Z J, Yuan M S (2004). Reservoir mechanism of shale gas and its distribution. Natural Gas Industry, 24(7): 15–18 (in Chinese)

    Google Scholar 

  • Zhu X M (2008). Sedimentary Petrology (4th ed). Beijing: Petroleum Industry Press, 208–286 (in Chinese)

    Google Scholar 

Download references

Acknowledgements

This research was supported by the National Science and Technology Major Project (2016ZX05041004-003) and the China Geological Survey Scientific Research Project (12120114019501 and 1212011220794). The authors are grateful for the valuable comments from two anonymous reviewers.

Author information

Authors and Affiliations

  1. School of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing, 100083, China

    Haihai Hou, Longyi Shao & Zhen Li

  2. No.105 Exploration Team, Qinghai Bureau of Coal Geological Exploration, Xining, 810007, China

    Yonghong Li, Wenlong Zhang & Huaijun Wen

Authors
  1. Haihai Hou
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Longyi Shao
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Yonghong Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Zhen Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Wenlong Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Huaijun Wen
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Longyi Shao.

Additional information

Haihai Hou is a post-doctoral scholar of geological resources and geological engineering in the College of Geosciences and Survey Engineering, China University of Mining and Technology, Beijing (CUMTB). He received his B.Sc. degree and M.Sc. degree from Henan Polytechnic University in 2009 and 2012, respectively. He obtained his Ph.D. degree from CUMTB in 2015. His research interests include sedimentology of coal-bearing measures and exploration of unconventional energy.

Longyi Shao is a professor at China University of Mining and Technology, Beijing, and serves as the vice Director of the College of Geosciences and Survey Engineering. He received his B.Sc. degree from Jiaozuo Mining Institute in 1983 and obtained his M.Sc. degree and Ph.D. degree from Beijing Graduate School of CUMTB in 1986 and 1989, respectively. He is currently leading an active group working on sedimentology and sequence stratigraphy of coal and oil basins in China.

Yonghong Li is the geological director and a senior engineer at the Qinghai Bureau of Coal Geological Exploration. His major research interests are coal and associated minerals assessment and exploration.

Zhen Li is a M.Sc. candidate of mineral resource prospecting and exploration in the College of Geosciences and Survey Engineering, China University of Mining and Technology, Beijing. He received his B.Sc. degree from Henan Polytechnic University in 2014. His research interests are exploration and development of coalbed methane and shale gas.

Wenlong Zhang is a deputy director at No.105 Exploration Team, Qinghai Bureau of Coal Geological Exploration. He received his B.Sc. degree from Shandong Agricultural University and obtained his M.Sc. degree from China University of Mining and Technology, Beijing. He has been engaged in coal geology and exploration, and basin analysis.

Huaijun Wen is a deputy director and senior engineer at the Qinghai Bureau of Coal Geological Exploration. He received his B.Sc. degree from Xi’an Mining Institute in 1987. His major research interests are coal geology and coal-bearing basin analysis.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Hou, H., Shao, L., Li, Y. et al. The pore structure and fractal characteristics of shales with low thermal maturity from the Yuqia Coalfield, northern Qaidam Basin, northwestern China. Front. Earth Sci. 12, 148–159 (2018). https://doi.org/10.1007/s11707-016-0617-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11707-016-0617-y

Keywords

Search

Navigation