Assessment of Unconventional Natural Gas Resources

Document Type : Review Article


Department of Polymer Engineering, Faculty of Engineering, Lorestan University, Khorramabad, Iran



In the 21st century, the petrochemical industry has experienced a significant increase in oil and gas consumption due to the growing global population and energy demand. Among nonrenewable resources, natural gas stands out as the cleanest option, making it an essential resource for the energy industry in comparison to other hydrocarbons. Unconventional gas, including shale gas, tight gas, coalbed methane, and gas hydrate, has emerged as a substantial hydrocarbon resource. This study aims to explore the environmental impacts, geological features, obstacles, and technical challenges associated with the exploitation of unconventional gas reservoirs, encompassing aspects such as energy demand, consumption and production, water pollution, greenhouse gas emissions, and reservoir geology properties. The paper also reviews the various approaches to developing unconventional gas in different countries, with a particular focus on the United States. The findings indicate that the feasible development of unconventional gas is indeed possible in different countries. However, the future outlook for this resource will heavily rely on several factors, including addressing environmental concerns, investment in renewable energy, and the state of global gas markets.


Main Subjects

Article Title [Persian]

ارزیابی مخازن گاز طبیعی غیرمتعارف

Author [Persian]

  • صادق صحرائی

استادیار گروه مهندسی پلیمر،دانشکده فنی مهندسی، دانشگاه لرستان، خرم آباد، ایران

Abstract [Persian]

در قرن بیست و یکم، حجم بزرگی از نفت و گاز در صنعت پتروشیمی مصرف می‌شود که با در نظر گرفتن جمعیت رو به رشد تقاضای انرژی جهانی رو به افزایش است. گاز طبیعی، پاک‌ترین منابع غیرقابل تجدید است که در مقایسه با دیگر هیدروکربن‌ها، به‌عنوان یک منبع انرژی مهم در نظر گرفته می‌شود. به‌طورکلی با توجه به حجم بزرگی از شیل گازی، ماسه‌ای متراکم گازی و بسترهای زغالی  و هیدرات گازی، مخازن گاز غیرمتداول به‌عنوان یک منبع عظیم هیدروکربن شناخته شده است. دامنه این مطالعه شامل تأثیرات زیست‌محیطی، ویژگی‌های زمین‌شناسی، موانع و چالش‌های فنی استخراج از مخازن غیرمتعارف  از جمله تقاضای انرژی، مصرف و تولید انرژی، آلودگی آب، انتشار گاز گلخانه‌ای و ویژگی‌های زمین‌شناسی مخزن است. این مقاله به بررسی روش‌های نوظهور در توسعه گاز غیرمتعارف در کشورهای مختلف با تمرکز بر ایالات‌متحده می‌پردازد. نتایج نشان می‌دهند که امکان توسعه گازی  غیرمتعارف در کشورهای مختلف وجود دارد، اما آینده آن به مسائل زیست‌محیطی، سرمایه‌گذاری در انرژی‌های تجدیدپذیر و بازارهای جهانی گاز بستگی دارد.

Keywords [Persian]

  • گاز غیرمتعارف
  • شیل گازی
  • ماسه‌ای متراکم گازی
  • بسترهای زغالی متان
  • هیدرات گازی
Adgate, J. L., Goldstein, B. D., & McKenzie, L. M. (2014). Potential public health hazards, exposures and health effects from unconventional natural gas development. Environmental science & technology, 48(15), 8307-8320.
Aguilera, R. F., Ripple, R. D., & Aguilera, R. (2014). Link between endowments, economics and environment in conventional and unconventional gas reservoirs. Fuel, 126, 224-238.
Amann-Hildenbrand, A., Ghanizadeh, A., & Krooss, B. M. (2012). Transport properties of unconventional gas systems. Marine and Petroleum Geology, 31(1), 90-99.
Aminian, K., & Rodvelt, G. (2014). Evaluation of coalbed methane reservoirs Coal Bed Methane (pp. 63-91): Elsevier.
Apergis, N., Mustafa, G., & Dastidar, S. G. (2021). An analysis of the impact of unconventional oil and gas activities on public health: New evidence across Oklahoma counties. Energy Economics, 97, 105223.
Barati, R., & Liang, J. T. (2014). A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells. Journal of Applied Polymer Science, 131(16).
Bavoh, C. B., Lal, B., & Keong, L. K. (2020). Introduction to gas hydrates. In Chemical Additives for Gas Hydrates (pp. 1-25). Springer, Cham.
Bizhani, M., Ardakani, O. H., Hawthorne, S. B., Cesar, J., Kurz, B., & Percival, J. B. (2022). CO2-Enhanced Oil Recovery Mechanism in Canadian Bakken Shale. Minerals, 12(6), 779.
Bocora, J. (2012). Global prospects for the development of unconventional gas. Procedia-Social and Behavioral Sciences, 65, 436-442.
Brown, S. P., & Yücel, M. K. (2013). The shale gas and tight oil boom: Us states’ economic gains and vulnerabilities. Council on Foreign Relations.
Buchanan, B. P., Auerbach, D. A., McManamay, R. A., Taylor, J. M., Flecker, A. S., Archibald, J. A., . . . Walter, M. T. (2017). Environmental flows in the context of unconventional natural gas development in the Marcellus Shale. Ecological Applications, 27(1), 37-55.
Caineng, Z., Zhang, G., Zhi, Y., Shizhen, T., Lianhua, H., Rukai, Z., . . . Zhiping, W. (2013). Concepts, characteristics, potential and technology of unconventional hydrocarbons: On unconventional petroleum geology. Petroleum Exploration and Development, 40(4), 413-428.
Capuano, L. (2018). International energy outlook 2018 (IEO2018). US Energy Information Administration (EIA): Washington, DC, USA, 2018, 21.
Chengzao, J. (2017). Breakthrough and significance of unconventional oil and gas to classical petroleum geology theory. Petroleum Exploration and Development, 44(1), 1-10.
Chengzao, J. I. A., Xiongqi, P. A. N. G., & Yan, S. O. N. G. (2021). The mechanism of unconventional hydrocarbon formation: Hydrocarbon self-sealing and intermolecular forces. Petroleum Exploration and Development, 48(3), 507-526.
Chengzao, J., Zheng, M., & Zhang, Y. (2012). Unconventional hydrocarbon resources in China and the prospect of exploration and development. Petroleum Exploration and Development, 39(2), 139-146.
Chong, Z. R., Yang, S. H. B., Babu, P., Linga, P., & Li, X.-S. (2016). Review of natural gas hydrates as an energy resource: Prospects and challenges. Applied Energy, 162, 1633-1652.
Chong, Z. R., Yin, Z., Zhao, J., & Linga, P. (2017). Recovering natural gas from gas hydrates using horizontal wellbore. Energy Procedia, 143, 780-785.
Conrad, C. L., Yin, Y. B., Hanna, T., Atkinson, A. J., Alvarez, P. J., Tekavec, T. N., ... & Wong, M. S. (2020). Fit-for-purpose treatment goals for produced waters in shale oil and gas fields. Water Research, 173, 115467.
Conti, J., Holtberg, P., Diefenderfer, J., LaRose, A., Turnure, J. T., & Westfall, L. (2016). International energy outlook 2016 with projections to 2040.
Cooper, J., Stamford, L., & Azapagic, A. (2016). Shale gas: a review of the economic, environmental, and social sustainability. Energy Technology, 4(7), 772-792.
Cronshaw, I., & Grafton, R. Q. (2016). Economic benefits, external costs and the regulation of unconventional gas in the United States. Energy Policy, 98, 180-186.
Dadwal, S. R. (2012). Can Unconventional Gas Be a Game-Changer for India? Strategic Analysis, 36(2), 247-259.
Delgado, M. S., Guilfoos, T., & Boslett, A. (2016). The cost of unconventional gas extraction: A hedonic analysis. Resource and Energy Economics, 46, 1-22.
Deziel, N. C., Clark, C. J., Casey, J. A., Bell, M. L., Plata, D. L., & Saiers, J. E. (2022). Assessing Exposure to Unconventional Oil and Gas Development: Strengths, Challenges, and Implications for Epidemiologic Research. Current Environmental Health Reports, 1-15.
Fangzheng, J. I. A. O. (2019). Re-recognition of “unconventional” in unconventional oil and gas. Petroleum Exploration and Development, 46(5), 847-855.
Fernando, F. N., & Stika, J. A. (2021). Exploration of unconventional oil and gas (UOAG) development on farmland: Findings from the bakken shale of north dakota. The Extractive Industries and Society, 8(1), 400-412.
Gabitto, J. F., & Tsouris, C. (2010). Physical properties of gas hydrates: A review. Journal of Thermodynamics, 2010.
Global, BP. (2017). BP statistical review of world energy June 2017.
Hancock, S., Boswell, R., & Collett, T. (2019). Development of Deepwater Natural Gas Hydrates. In Offshore Technology Conference. Offshore Technology Conference.
Holz, F., Richter, P. M., & Egging, R. (2015). A global perspective on the future of natural gas: Resources, trade, and climate constraints: Oxford University Press.
Hongjun, W., Feng, M., Xiaoguang, T., Zuodong, L., Zhang, X., Zhenzhen, W., . . . Liuyan, Y. (2016). Assessment of global unconventional oil and gas resources. Petroleum Exploration and Development, 43(6), 925-940.
Howarth, R. W., Santoro, R., & Ingraffea, A. (2011). Methane and the greenhouse-gas footprint of natural gas from shale formations. Climatic change, 106(4), 679.
Hu, T., Pang, X., Wang, X., Pang, H., Tang, L., Pan, Z., . . . Pang, Y. (2017). Source rock characteristics of Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin, northwest China, and its significance on tight oil source and occurrence. Geological Journal, 52(4), 624-645.
Hultman, N., Rebois, D., Scholten, M., & Ramig, C. (2011). The greenhouse impact of unconventional gas for electricity generation. Environmental Research Letters, 6(4), 044008.
Islam, M. M., & Hasanuzzaman, M. (2020). Introduction to energy and sustainable development. In Energy for sustainable development (pp. 1-18). Academic Press.
Jackson, R., Gorody, A., Mayer, B., Roy, J., Ryan, M., & Van Stempvoort, D. (2013). Groundwater protection and unconventional gas extraction: The critical need for field-based hydrogeological research. Groundwater, 51(4), 488-510.
Janda, K., & Kondratenko, I. (2018). An Overwiew of Economic Impacts of Shale Gas on EU Energy Security, MPRA Paper No. 83945, University Library of Munich, Germany.
Jia, Ailin, et al. “Predictions on natural gas development trend in China for the next fifteen years.” Journal of Natural Gas Geoscience (2021).
Jia, C. Z., Pang, X. Q., & Song, Y. (2023). Whole petroleum system and ordered distribution pattern of conventional and unconventional oil and gas reservoirs. Petroleum Science, 20(1), 1-19.
Jia, Q., Liu, D., Cai, Y., Fang, X., & Li, L. (2021). Petrophysics characteristics of coalbed methane reservoir: A comprehensive review. Frontiers of Earth Science, 15(2), 202-223.
Jianchao, H., Zhiwei, W., & Pingkuo, L. (2018). Current states of coalbed methane and its sustainability perspectives in China. International Journal of Energy Research.
Jiang, Z.-X., Li, Z., Li, F., Pang, X.-Q., Yang, W., Liu, L.-F., & Jiang, F.-J. (2015). Tight sandstone gas accumulation mechanism and development models. Petroleum Science, 12(4), 587-605.
Jin, Z., Zhang, J., & Tang, X. (2022). Unconventional natural gas accumulation system. Natural Gas Industry B, 9(1), 9-19.
Joshi, D., Prajapati, P., Sharma, P., & Sharma, A. (2022). Past, present and future of Coal Bed Methane (CBM): a review with special focus on the Indian scenario. International Journal of Coal Preparation and Utilization, 1-26.
Kamali, M. R., & Rezaee, M. R. (2012). Identification and evaluation of unconventional hydrocarbon reserves: examples from Zagros and Central Iran Basins. Journal of Petroleum Science and Technology, 2(1), 27-36.
Kamari, A., Li, L., & Sheng, J. J. (2018). Effects of rock pore sizes on the PVT properties of oil and gas-condensates in shale and tight reservoirs. Petroleum, 4(2), 148-157.
Karthikeyan, G., Kumar, A., Shrivastava, A., & Srivastava, M. (2018). Overpressure estimation and productivity analysis for a Marcellus Shale gas reservoir, southwest Pennsylvania: A case study. The Leading Edge, 37(5), 344-349.
Khan, H. J., Spielman-Sun, E., Jew, A. D., Bargar, J., Kovscek, A., & Druhan, J. L. (2021). A critical review of the physicochemical impacts of water chemistry on shale in hydraulic fracturing systems. Environmental science & technology, 55(3), 1377-1394.
Kirat, Y. (2021). The US shale gas revolution: An opportunity for the US manufacturing sector?. International Economics, 167, 59-77.
Koh, C. A., & Sloan, E. D. (2007). Natural gas hydrates: Recent advances and challenges in energy and environmental applications. AIChE journal, 53(7), 1636-1643.
Kotsakis, A. (2012). The regulation of the technical, environmental and health aspects of current exploratory shale gas extraction in the United Kingdom: initial lessons for the future of European Union energy policy. Review of European Community & International Environmental Law, 21(3), 282-290.
Le, M. T. (2017). Unconventional gas development in Vietnam: opportunities and challenges. The Journal of World Energy Law & Business, 10(1), 14-29.
Liang, C., Jiang, Z., Zhang, C., Guo, L., Yang, Y., & Li, J. (2014). The shale characteristics and shale gas exploration prospects of the Lower Silurian Longmaxi shale, Sichuan Basin, South China. Journal of Natural Gas Science and Engineering, 21, 636-648.
Mahmood, M. F., Ahmad, Z., & Ehsan, M. (2018). Total organic carbon content and total porosity estimation in unconventional resource play using integrated approach through seismic inversion and well logs analysis within the Talhar Shale, Pakistan. Journal of Natural Gas Science and Engineering, 52, 13-24.
Mao, Z., Cheng, L., Liu, D., Li, T., Zhao, J., & Yang, Q. (2022). Nanomaterials and technology applications for hydraulic fracturing of unconventional oil and gas reservoirs: A state-of-the-art review of recent advances and perspectives. ACS omega, 7(34), 29543-29570.
Marsden, H., Basu, S., Striolo, A., & MacGregor, M. (2022). Advances of nanotechnologies for hydraulic fracturing of coal seam gas reservoirs: Potential applications and some limitations in Australia. International Journal of Coal Science & Technology, 9(1), 27.
McGlade, C., Speirs, J., & Sorrell, S. (2013). Unconventional gas-a review of regional and global resource estimates. Energy, 55, 571-584.
McKenzie, L. M., Witter, R. Z., Newman, L. S., & Adgate, J. L. (2012). Human health risk assessment of air emissions from development of unconventional natural gas resources. Science of the Total Environment, 424, 79-87.
McLaughlin, M. C., Borch, T., & Blotevogel, J. (2016). Spills of hydraulic fracturing chemicals on agricultural topsoil: biodegradation, sorption, and co-contaminant interactions. Environmental science & technology, 50(11), 6071-6078.
Mei, Y., Liu, W., Wang, J., & Bentley, Y. (2022). Shale gas development and regional economic growth: Evidence from Fuling, China. Energy, 239, 122254.
Miao, Y., Li, X., Zhou, Y., Wu, K., Chang, Y., Xiao, Z., ... & Lin, W. (2018). A dynamic predictive permeability model in coal reservoirs: Effects of shrinkage behavior caused by water desorption. Journal of Petroleum Science and Engineering, 168, 533-541.
Milkov, A. V., Faiz, M., & Etiope, G. (2020). Geochemistry of shale gases from around the world: Composition, origins, isotope reversals and rollovers, and implications for the exploration of shale plays. Organic Geochemistry, 143, 103997.
Mohamed, T., & Mehana, M. (2020). Coalbed methane characterization and modeling: review and outlook. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 1-23.
Nelson, P. H. (2009). Pore-throat sizes in sandstones, tight sandstones, and shales. AAPG bulletin, 93(3), 329-340.
Nia, S. F., Dasani, D., Tsotsis, T. T., & Jessen, K. (2016). An integrated approach for the characterization of shales and other unconventional resource materials. Industrial & Engineering Chemistry Research, 55(12), 3718-3728.
Omara, M., Sullivan, M. R., Li, X., Subramanian, R., Robinson, A. L., & Presto, A. A. (2016). Methane emissions from conventional and unconventional natural gas production sites in the Marcellus Shale Basin. Environmental science & technology, 50(4), 2099-2107.
Orak, N. H., Reeder, M., & Pekney, N. J. (2021). Identifying and quantifying source contributions of air quality contaminants during unconventional shale gas extraction. Atmospheric Chemistry and Physics, 21(6), 4729-4739.
Patterson, L. A., Konschnik, K. E., Wiseman, H., Fargione, J., Maloney, K. O., Kiesecker, J., . . . Trainor, A. (2017). Unconventional oil and gas spills: Risks, mitigation priorities, and state reporting requirements. Environmental science & technology, 51(5), 2563-2573.
Reins, L. (2014). In search of the legal basis for environmental and energy regulation at the EU level: The case of unconventional gas extraction. Review of European, Comparative & International Environmental Law, 23(1), 125-133.
Rutter, E., Mecklenburgh, J., & Bashir, Y. (2022). Matrix gas flow through “impermeable” rocks-shales and tight sandstone. Solid Earth, 13(3), 725-743.
Sahraei, S., Daliri, A., Asgari, M. (2022). Renewable energy book: Noor Publication.
Satter, A., & Iqbal, G. M. (2015). Reservoir engineering: the fundamentals, simulation, and management of conventional and unconventional recoveries. Gulf Professional Publishing.
Scanlon, B. R., Reedy, R. C., & Nicot, J.-P. (2014). Comparison of water use for hydraulic fracturing for unconventional oil and gas versus conventional oil. Environmental science & technology, 48(20), 12386-12393.
Schneising, O., Burrows, J. P., Dickerson, R. R., Buchwitz, M., Reuter, M., & Bovensmann, H. (2014). Remote sensing of fugitive methane emissions from oil and gas production in North American tight geologic formations. Earth’s Future, 2(10), 548-558.
Shirazi, M., Ghasemi, A., & Šimurina, J. (2022). The impact of the North American shale gas technology on the US’energy security: the case of natural gas. International Journal of Sustainable Energy, 41(7), 810-831.
Soeder, D. J. (2018). The successful development of gas and oil resources from shales in North America. Journal of Petroleum Science and Engineering, 163, 399-420.
Solarin, S. A., & Bello, M. O. (2020). The impact of shale gas development on the US economy: Evidence from a quantile autoregressive distributed lag model. Energy, 205, 118004.
Song, Y., Li, Z., Jiang, L., & Hong, F. (2015). The concept and the accumulation characteristics of unconventional hydrocarbon resources. Petroleum Science, 12(4), 563-572.
Stringfellow, W. T., Domen, J. K., Camarillo, M. K., Sandelin, W. L., & Borglin, S. (2014). Physical, chemical, and biological characteristics of compounds used in hydraulic fracturing. Journal of hazardous materials, 275, 37-54.
Su, X., Li, F., Su, L., & Wang, Q. (2020). The experimental study on integrated hydraulic fracturing of coal measures gas reservoirs. Fuel, 270, 117527.
Tan, P., Jin, Y., Hou, B., Yuan, L., & Xiong, Z. (2019). Experimental investigation of hydraulic fracturing for multi-type unconventional gas co-exploitation in Ordos basin. Arabian Journal for Science and Engineering, 44(12), 10503-10511.
Tian, J., Liu, J., Elsworth, D., Leong, Y. K., Li, W., & Zeng, J. (2022). Shale gas production from reservoirs with hierarchical multiscale structural heterogeneities. Journal of Petroleum Science and Engineering, 208, 109380.
Tong, X., Zhang, G., Wang, Z., Wen, Z., Tian, Z., Wang, H., . . . Wu, Y. (2018). Distribution and potential of global oil and gas resources. Petroleum exploration and development, 45(4), 779-789.
Vengosh, A., Jackson, R. B., Warner, N., Darrah, T. H., & Kondash, A. (2014). A critical review of the risks to water resources from unconventional shale gas development and hydraulic fracturing in the United States. Environmental science & technology, 48(15), 8334-8348.
Vengosh, A., Mitch, W. A., & McKenzie, L. M. (2017). Environmental and human impacts of unconventional energy development: ACS Publications.
Vinson, D. S., Blair, N. E., Martini, A. M., Larter, S., Orem, W. H., & McIntosh, J. C. (2017). Microbial methane from in situ biodegradation of coal and shale: a review and reevaluation of hydrogen and carbon isotope signatures. Chemical Geology, 453, 128-145.
Wallmann, K., & Schicks, J. M. (2020). Gas hydrates as an unconventional hydrocarbon resource. Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate, 651-666.
Wang, Q., Wang, R., Sun, J., Sun, J., Lu, C., Lv, K., ... & Qu, Y. (2021). Effect of Drilling Fluid Invasion on Natural Gas Hydrate Near-Well Reservoirs Drilling in a Horizontal Well. Energies, 14(21), 7075.
Wang, Y., Zhu, Y., Liu, Y., & Chen, S. (2018). Reservoir characteristics of coal-shale sedimentary sequence in coal-bearing strata and their implications for the accumulation of unconventional gas. Journal of Geophysics and Engineering, 15(2), 411.
Willems, D. J., Kumar, A., & Nugegoda, D. (2022). The acute toxicity of salinity in onshore unconventional gas waters to freshwater invertebrates in receiving environments: A systematic review. Environmental Toxicology and Chemistry, 41(12), 2928-2949.
Willems, D. J., Kumar, A., & Nugegoda, D. (2023). Mixture Toxicity of Three Unconventional Gas Fracking Chemicals, Barium, O-Cresol, and Sodium Chloride, to the Freshwater Shrimp Paratya australiensis. Environmental Toxicology and Chemistry, 42(2), 481-494.
Yap, N. T. (2016). Unconventional shale gas development: challenges for environmental policy and EA practice. Impact Assessment and Project Appraisal, 34(2), 97-109.
Yin, T., Liu, D., Cai, Y., Zhou, Y., & Yao, Y. (2017). Size distribution and fractal characteristics of coal pores through nuclear magnetic resonance cryoporometry. Energy & Fuels, 31(8), 7746-7757.
Yoon, S. H., Joe, Y. J., Koh, C. S., Woo, J. H., & Lee, H. S. (2018). Sedimentary processes and depositional environments of the gas-bearing Horn River shale in British Columbia, Canada. Geosciences Journal, 22(1), 33-46.
Yu, Y., ZHANG, X. W., Liu, J. W., Lee, Y., & Li, X. (2021). Natural gas hydrate resources and hydrate technologies: a review and analysis of the associated energy and global warming challenges. Energy & Environmental Science.
Zhang, W., Liang, J., Wei, J., Su, P., Lin, L., & Huang, W. (2019). Origin of natural gases and associated gas hydrates in the Shenhu area, northern South China Sea: Results from the China gas hydrate drilling expeditions. Journal of Asian Earth Sciences, 183, 103953.
Zou, C., Yang, Z., He, D., Wei, Y., Li, J., Jia, A., . . . Li, J. (2018). Theory, technology and prospects of conventional and unconventional natural gas. Petroleum Exploration and Development-Elsevier, 45(4), 604-618.
Zou, C., Qiu, Z., Zhang, J., Li, Z., Wei, H., Liu, B., ... & Li, Y. (2022). Unconventional petroleum sedimentology: A key to understanding unconventional hydrocarbon accumulation. Engineering.