Physicochemical Characteristics of Hard Brittle Shale and Associated Wellbore Instability

  • Kai ZhaoEmail author
  • Huizhu Sun
  • Liangbin Dou
  • Jiyong Han
Conference paper
Part of the Springer Series in Geomechanics and Geoengineering book series (SSGG)


Wellbore instability in hard brittle shale is a key problem restricting the effective development of deep resources and unconventional shale gas resources which has not been solved effectively. Based on this, different experiments including x-ray diffraction, scanning electron microscope, hydrate swelling test, rock mechanics test were conducted in order to understand the components and microcosmic structure of the hard brittle shale and its physicochemical characteristics comprehensively. In addition, the properties of the collapsing block from the borehole were analysed through comparison before and after soaked in water. The results showed that unlike soft shale, the content of water sensitivity mineral such as montmorillonite within hard brittle shale was low and swelling capability due to water absorption was consequently low, but internal micro-fractures were developed, so the main reasons of wellbore instability are possible not chemical factors, but that the crack propagation and strength weakened. In drilling engineering, effective countermeasures are mainly including two categories; one is improving drilling fluid properties such as sealing, rheological property, wettability to slow down the drilling fluid invasion into micro-cracks within hard brittle shale, and the other is increasing the strength and reducing the stress acting on the rock surrounding wellbore through increasing drilling mud column pressure, reducing disturbance and the impact of drilling tool, optimizing well trajectory and so on.


Hard brittle shale Physicochemical characteristics Wellbore instability 



The authors gratefully acknowledge the support of National Natural Science Foundation of China (Grant No. 51604225 and Grant No. 51604224).


  1. 1.
    Li W, Zou H, Wu C, Wang Y (2013) An analysis of shale gas development in view of engineering technologies. Acta Petrolei Sin 34(6):1218–1224Google Scholar
  2. 2.
    Jia C, Pang X (2015) Research processes and main development directions of deep hydrocarbon geological theories. Acta Petrolei Sin 36(12):1457–1469Google Scholar
  3. 3.
    Gough DIS, Bell JS (1982) Stress orientations from borehole wall fractures with examples from Colorado, East Texas, and Northern Canada. Can J Earth Sci 19:1358–1370CrossRefGoogle Scholar
  4. 4.
    Gennanovich LN, Roegiers JC, Dyskin AV (2006) A model for borehole breakouts in brittle rocks. In: Proceedings of international conference on systems biology, Stockholm, Sweden, May 2006. pp 1–7Google Scholar
  5. 5.
    Younessi A, Rasouli V (2010) A fracture sliding potential index for wellbore stability analysis. Int J Rock Mech Min Sci 47:927–939CrossRefGoogle Scholar
  6. 6.
    Liu Y, Bai J, Huang R, Zhou Y (1998) A study on stability of brittle shale wellbore. Acta Petrolei Sin 19(1):85–88Google Scholar
  7. 7.
    Santarelli FJ, Dardeau C, Zurdo C (1992) Drilling through highly fractured formations: a problem, a model, and a cure. In: SPE annual technical conference and exhibition, Washington, D.C., October 1992. pp 481–490Google Scholar
  8. 8.
    Van Oort E (2003) On the physical and chemical stability of shales. J Petrol Sci Eng 38:213–235CrossRefGoogle Scholar
  9. 9.
    Wen H, Chen M, Jin Y, Wang K, Xia Y, Dong J, Niu C (2014) A chemo-mechanical coupling model of deviated borehole stability in hard brittle shale. Pet Explor Dev 41(6):748–754CrossRefGoogle Scholar
  10. 10.
    Shi B, Xia B, Lin Y, Xu J (2012) CT imaging and mechanism analysis of crack development by hydration in hard-brittle shale formations. Acta Petrolei Sin 33(1):137–142CrossRefGoogle Scholar
  11. 11.
    Aadnoy BS, Chenevert ME (1987) Stability of highly inclined boreholes. SPE Drill Eng 2(4):364–374CrossRefGoogle Scholar
  12. 12.
    Aadnoy BS, Larson K (1989) Method for fracture-gradient prediction for vertical and inclined boreholes. SPE Drill Eng 4(2):99–103CrossRefGoogle Scholar
  13. 13.
    Zhu H, Deng J, Liu S, Yan W, Chen Z, Wen M, Peng C (2013) A prediction model for the hydraulic fracture initiation pressure in oriented perforation. Acta Petrolei Sin 34(3):556–562Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  • Kai Zhao
    • 1
    Email author
  • Huizhu Sun
    • 1
  • Liangbin Dou
    • 1
  • Jiyong Han
    • 1
  1. 1.College of Petroleum Engineering, Xi’an Shiyou UniversityXi’anChina

Personalised recommendations