On the mitigating environmental aspects of a vertical well in underground coal gasification method

  • Mohammadreza Shahbazi
  • Mehdi NajafiEmail author
  • Mohammad Fatehi Marji
Original Article


Underground coal gasification (UCG) is an energy production pathway in underground coal deposits with the potential advantage of decreasing the greenhouse gas emissions during the energy extraction process. The environmental benefits of UCG are mainly due to eliminating (i) conventional mining operations, (ii) the presence of coal miners in the underground, (iii) coal washing and fines disposal, and (iv) coal stockpiling and coal transportation activities. Furthermore, UCG has a capacity of great potential to provide a clean coal energy source by the implementing carbon capture and storage techniques as part of the energy extraction process. In this method, coal seams in the underground were converted into syngas including hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) gasses with an advanced thermochemical process. UCG operation effected significant geomechanical changes to the overburden strata. In this process, the vertical well (especially the production well) was mainly affected by the mechanical stresses and the thermal stress, induced by the high syngas temperature. This high temperature changed the mechanical, thermal, and physical properties of the coal seam and its surrounding rocks (the host rocks), finally causing instability of the vertical well, while leading to serious production and environmental problems. One of these environmental issues is the possibility of syngas leakage in to the environment, resulting in water pollution and acidification. In addition, the released syngas could trigger global warming and air pollution. This research evaluated environmental aspects of UCG vertical well (production well) based on the stability analysis. Therefore, a flow sheet form was developed for three-dimensional thermomechanical numerical modeling of an UCG vertical well by explicit Lagrangian finite difference method. In this model, a criterion was established based on normalized yielded zone area to assess the stability conditions. The methodology was able to capture all factors that influence the instability of UCG well while selecting suitable mud pressure and lining system during the well drilling process. Hence, when wellbore integrity issues arose during drilling, the mitigation strategies were applied to rectify these problems. The results demonstrated that the vertical well should be drilled at a constant mud pressure of 9 MPa (megapascal), thus causing minimum environmental problems. The thermomechanical modeling provided an opportunity to assess the potential environmental impacts and identify reliable global climate change mitigation strategies.


Underground coal gasification (UCG) Vertical production well Greenhouse gas emissions Environmental aspects 


  1. Akbarzadeh H, Chalaturnyk RJ (2013) Coupled fluid-thermal-mechanical analyses of a deep underground coal gasification cavity. J Archit Civil Eng Quest J 1(1):01–14CrossRefGoogle Scholar
  2. Akbarzadeh H, Chalaturnyk RJ (2016) Sequentially coupled flow-geomechanical modeling of underground coal gasification for a three-dimensional problem. Mitig Adapt Strateg Glob Chang 21(4):577–594CrossRefGoogle Scholar
  3. Anon (2005) Basic design of Tabas coal mine project, report-mining. Vol 1 of 5Google Scholar
  4. Brown KM (2012) In situ coal gasification: an emerging technology. Proc Am Soc Min Reclamat 2012:51–70CrossRefGoogle Scholar
  5. Burton E, Friedmann J, Upadhye R (2006) Best practices in underground coal gasification, Draft. US DOE contract no W-7405-Eng-48. Lawrence Livermore National Laboratory, LivermoreGoogle Scholar
  6. Couch GR (2009) Underground coal gasification. IEA Clean Coal Center, International Energy Agency, London ISBN 978-92-9029-471-9Google Scholar
  7. Daggupati S, Mandapati RN, Mahajani MS (2010) Laboratory studies on combustion cavity growth in lignite coal blocks in the context of underground coal gasification. Energy 35(6):2374–2386CrossRefGoogle Scholar
  8. Das B, Chatterjee R (2017) Wellbore stability analysis and prediction of minimum mud weight for few wells in Krishna-Godavari Basin, India. International Journal of Rock Mechanics and Mining sciences, Dept. of Applied Geophysics, Indian School of Mines, Dhanbad. CrossRefGoogle Scholar
  9. Elahi SM (2016) Geomechanical modeling of underground coal gasification (Doctoral dissertation, University of Calgary)Google Scholar
  10. Elyasi A, Goshtasbi K (2015) Numerical modeling of the stability of horizontal multidrain oil wells. China Ocean Eng 29(5):719–732CrossRefGoogle Scholar
  11. Fjar E, Holt RM, Raaen AM, Risnes R, Horsrud P (2008) Petroleum related rock mechanics. ElsevierGoogle Scholar
  12. Goodman RE (1989) Introduction to rock mechanics, vol 2. Wiley, New York, p 576Google Scholar
  13. Gregg DW (1977) Ground subsidence resulting from underground gasification of coal.UCRL-52255. Lawrence Livermore Laboratory, University of CaliforniaGoogle Scholar
  14. Gregg DW, Edgar TF (1978) Underground coal gasification. Chem Eng J 24(5):753–781Google Scholar
  15. Imran M, Kumar D, Kumar N, Qayyum A, Saeed A, Bhatti MS (2014) Environmental concerns of underground coal gasification. Renew Sust Energ Rev 31:600–610CrossRefGoogle Scholar
  16. Itasca (2012) User manual for FLAC3D, version.5.0. Itasca Consulting Group Inc, MinnesotaGoogle Scholar
  17. Jamshidi E, Amani M (2014) Numerical wellbore stability analysis using discrete element models. Pet Sci Technol 32(8):974–982CrossRefGoogle Scholar
  18. Khan MM, Mmbaga JP, Shirazi AS, Liu Q, Gupta R (2015) Modelling underground coal gasification—a review. Energies 8(11):12603–12668. CrossRefGoogle Scholar
  19. Laciak M, Kostúr K, Durdán M, Kačur J, Flegner P (2016) The analysis of the underground coal gasification in experimental equipment. Energy 114:332–343CrossRefGoogle Scholar
  20. Laouafa F, Farret R, Vidal-Gilbert S, Kazmierczak JB (2016) Overview and modeling of mechanical and thermomechanical impact of underground coal gasification exploitation. Mitig Adapt Strateg Glob Chang 21(4):547–576CrossRefGoogle Scholar
  21. Luo X, Tan Q, Luo C, Wang Z (2008) Microseismic monitoring of burn front in an underground coal gasification experiment. In The 42nd US Rock Mechanics Symposium (USRMS). American Rock Mechanics AssociationGoogle Scholar
  22. Luo Y, Coertzen M, Dumble S (2009) Comparison of UCG cavity growth with CFD model predictions. In 7th International Conference on CFD in the Minerals and Process Industries CRISO, Melbourne, AustraliaGoogle Scholar
  23. Marg N (2009) Environmental impact assessment for proposed underground coal gasification (UCG) pilot project at Vastan mine block, Surat in Gujarat. National Environmental Engineering Research InstituteGoogle Scholar
  24. McInnis J, Singh S, Huq I (2016) Mitigation and adaptation strategies for global change via the implementation of underground coal gasification. Mitig Adapt Strateg Glob Chang 21(4):479–486CrossRefGoogle Scholar
  25. McLellan PJ, Hawkes CD (2001) Borehole stability, sand production and microseismic monitoring. Innovations for Horizontal Wells, SPE/CIM Horizontal Well Conference, Calgary, AlbertaGoogle Scholar
  26. Mellors R, Yang X, White JA, Ramirez A, Wagoner J, Camp DW (2016) Advanced geophysical underground coal gasification monitoring. Mitig Adapt Strateg Glob Chang 21(4):487–500CrossRefGoogle Scholar
  27. Mohanto S, Singh K, Chakraborty T, Basu D (2014) Cyclic thermo-mechanical analysis of wellbore in underground compressed air energy storage cavern. Geotech Geol Eng 32(3):601–616. CrossRefGoogle Scholar
  28. Najafi M (2014) Thermo-mechanical modeling of panels dimensions in underground coal gasification method - PhD Thesis, Shahrood University of Technology, Iran. (In Persian)Google Scholar
  29. Najafi M, Jalali SM, KhaloKakaie R (2014) Thermal–mechanical–numerical analysis of stress distribution in the vicinity of underground coal gasification (UCG) panels. Int J Coal Geol 134:1–6CrossRefGoogle Scholar
  30. Nitao J, Buscheck T, Ezzedine S, Friedman S, Camp D (2010) An integrated 3-D UCG model for prediction cavity growth, production gas, and interaction with the host environment. 27th Annual International Pittsburgh Coal Conference, Istanbul, TurkeyGoogle Scholar
  31. Nitao JJ, Camp DW, Buscheck TA, White JA, Burton GC, Wagoner JL, Chen M (2011) Progress on a new integrated 3-D UCG simulator and its initial application. International Pittsburgh Coal ConferenceGoogle Scholar
  32. Otto C, Kempka T, Kapusta K, Stańczyk K (2016) Fault reactivation can generate hydraulic short circuits in underground coal gasification—new insights from regional-scale thermo-mechanical 3D modeling. Minerals 6(4):101CrossRefGoogle Scholar
  33. Perkins G, Sahajwalla V (2006) A numerical study of the effects of operating conditions and coal properties on cavity growth in underground coal gasification. Energy Fuel 20(2):596–608CrossRefGoogle Scholar
  34. Roddy DJ, Younger PL (2010) Underground coal gasification with CCS: a pathway to decarbonising industry. Energy Environ Sci 3(4):400–407CrossRefGoogle Scholar
  35. Sarraf A (2012) CFD simulation of underground coal gasification. MSc Thesis, Department of Chemical and Materials Engineering, University of AlbertaGoogle Scholar
  36. Sarraf A, Mmbaga J, Gupta P, Hayes RE (2011) Modeling cavity growth during underground coal gasification. COMSOL conferences in BostonGoogle Scholar
  37. Stańczyk K, Kapusta K, Wiatowski M, Świądrowski J, Smoliński A, Rogut J, Kotyrba A (2012) Experimental simulation of hard coal underground gasification for hydrogen production. Fuel 91(1):40–50CrossRefGoogle Scholar
  38. Synfuels SH (2012) Swan Hills in-situ coal gasification technology development final outcomes report. Alberta Innovates-Energy and Environment Solutions ReportGoogle Scholar
  39. Tan Q, Luo X, Li S (2008) Numerical modeling of thermal stress in a layered rock mass. In the 42nd US Rock Mechanics Symposium (USRMS). American Rock Mechanics AssociationGoogle Scholar
  40. Tian H (2013) Development of a thermo-mechanical model for rocks exposed to high temperatures during underground coal gasification. PhD thesis in RWTH Aachen University, PotsdamGoogle Scholar
  41. Vorobiev OY, Morris JP, Antoun TH, Friedmann S J (2008) Geomechanical simulations related to UCG activities. In International Pittsburgh Coal Conference, Pittsburgh, PAGoogle Scholar
  42. Wiatowski M, Kapusta K, Ludwik-Pardała M, Stańczyk K (2016) Ex-situ experimental simulation of hard coal underground gasification at elevated pressure. Fuel 184:401–408CrossRefGoogle Scholar
  43. Yang D, Sarhosis V, Sheng Y (2014) Thermal–mechanical modelling around the cavities of underground coal gasification. J Energy Inst 87(4):321–329CrossRefGoogle Scholar
  44. Zoback MD (2007) Reservoir geomechanics, First published. Cambridge University Press, United KingdomCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V., part of Springer Nature 2018

Authors and Affiliations

  • Mohammadreza Shahbazi
    • 1
  • Mehdi Najafi
    • 1
    Email author
  • Mohammad Fatehi Marji
    • 1
  1. 1.Department of Mining and Metallurgical EngineeringYazd UniversityYazdIran

Personalised recommendations