Overview of enhanced geothermal system (EGS) based on excavation in China

doi:10.13745/j.esf.2020.1.20

Abstract

Abstract:

Geothermal energy is a permanent, renewable, inexhaustible and clean energy stored in regosol, fluid and magmatic bodies in the Earth’s crust. Its exploitation and utilization, mainly hot dry rock (HDR), may become a meaningful way to solve the future energy crisis. The enhanced geothermal system (EGS) is the primary method used in the exploitation of HDR up till the present time. Because of the complexity of geological environment and dependency of hydraulic measures on natural fissures, most of EGS projects have many technical shortcomings, such as insufficient thermal storage volume and heat transfer area, low working fluid flow rate, low terminal temperature and induced earthquake risk, making large-scale commercialization of DHR unachievable. The prospects of the enhanced geothermal system based on excavation technology (EGS-E) inspired us to find breakthroughs overcoming the technical difficulties and limitations of EGS. In this paper, we discussed EGS-E in great detail on its operation fundamentals, engineering principles and technical advantages based on a conceptual model. By adopting mining technologies, such as excavation, blasting and caving, EGS-E can significantly overcome geological environmental restrictions on thermal storage quality to form a unique fracturing system of geothermal reservoir as well as a special thermal energy exchange system. It has the advantages of building up customized thermal storage, forming sufficient heat transfer areas, maintaining stable working fluid flow rate and temperature, and reducing earthquake risks, thus provides a brand-new scheme for the commercialization of HDR geothermal energy.

Key words: geothermal energy, hot dry rock, deep geothermal exploitation, enhanced geothermal system

CLC Number:

P314.2

KANG Fangchao, TANG Chun’an. Overview of enhanced geothermal system (EGS) based on excavation in China[J]. Earth Science Frontiers, 2020, 27(1): 185-193.

Figures/Tables 8

Fig.1 Distribution range of different types of dry hot rock. Adapted from [1].

Fig.2 A conceptual two-well EGS in dry hot rock exploitation. Adapted from [12].

Table 1 Limiting values of EGS related factors satisfying power generation capacity[3]

影响因素	限定值
流体生产率	50~100 L/s
井口流体温度	150~200 ℃
有效热交换面积	>2×10⁶ m²
热储体积	>2×10⁸ m³
流体阻力	<0.1 MPa/(kg·s^-1)
水量损失	<10%

Fig.3 A schematic diagram of EGS-E engineering model

Fig.4 A schematic diagram of EGS-E fracturing engineering

Fig.5 Enlarged slice map of EGS-E fracturing engineering profile

Fig.6 Enlarged slice map of EGS-E thermal storage engineering profile

Fig.7 Flow chart of EGS-E thermal energy extraction

References 55

[1]	李德威, 王焰新. 干热岩地热能研究与开发的若干重大问题[J]. 地球科学: 中国地质大学学报, 2015, 40(11):1858-1869.
[2]	KRUGER P, OTTE C E. Geothermal energy: resources, production, stimulation[M]. Palo Alto: Stanford University Press, 1973: 637-639.
[3]	RYBACH L. Geothermal energy: sustainability and the environment[J]. Geothermics, 2003, 32(4/5/6):463-470. DOI URL
[4]	BROWN D W, DUCHANE D V, HEIKEN G, et al. Mining the Earth’s heat: hot dry rock geothermal energy[M]. Heidelberg, Berlin: Springer-Verlag, 2012: 136-145.
[5]	胡剑, 苏正, 吴能友, 等. 增强型地热系统热流耦合水岩温度场分析[J]. 地球物理学进展, 2014, 29(3):1391-1398.
[6]	廖志杰, 万天丰, 张振国. 增强型地热系统:潜力大、开发难[J]. 地学前缘, 2015, 22(1):335-344.
[7]	WHETTEN J T, DENNIS B R, DREESEN D S, et al. The US Hot Dry Rock project[J]. Geothermics, 1987, 16(4):331-339. DOI URL
[8]	GOLDEMBERG J. World energy assessment: energy and the challenge of sustainability[M]. New York: United Nations Development Programme, 2000: 24-26.
[9]	王贵玲, 张薇, 梁继运, 等. 中国地热资源潜力评价[J]. 地球学报, 2017, 38(4):449-459.
[10]	FENG Y, CHEN X, XU X F. Current status and potentials of enhanced geothermal system in China: a review[J]. Renewable and Sustainable Energy Reviews, 2014, 33:214-223. DOI URL
[11]	汪集旸, 胡圣标, 庞忠和, 等. 中国大陆干热岩地热资源潜力评估[J]. 科技导报, 2012, 30(32):25-31.
[12]	MIT. The future of geothermal energy: impact of enhanced geothermal systems (EGS) on the United States in the 21st Century[M]. Cambridge, MA: MIT Press, 2006: 9-11.
[13]	SASAKI S, KAIEDA H. Determination of stress state from focal mechanisms of microseismic events induced during hydraulic injection at Hijiori HDR site[J]. Pure and Applied Geophysics, 2002, 159:489-516. DOI URL
[14]	BERTANI R. Geothermal power generation in the world 2010-2014 update report[J]. Geothermics, 2016, 60:31-43. DOI URL
[15]	BREEDE K, DZEBISASHVILI K, LIU X, et al. A systematic review of enhanced (or engineered) geothermal systems: past, present and future[J]. Geothermal Energy, 2013, 1(1):4. DOI URL
[16]	BARIA R, BAUMGÄRTNER J, RUMMEL F, et al. HDR/HWR reservoirs: concepts, understanding and creation[J]. Geothermics, 1999, 28(4/5):533-552. DOI URL
[17]	PARKER R. The Rosemanowes HDR project 1983-1991[J]. Geothermics, 1999, 28(4/5):603-615. DOI URL
[18]	KWIATEK G, BOHNHOFF M, DRESEN G, et al. Microseismicity induced during fluid-injection: a case study from the geothermal site at Groß Schönebeck, North German Basin[J]. Acta Geophysica, 2010, 58(6):995-1020. DOI URL
[19]	CUENOT N, CHARLÉTY J, DORBATH L, et al. Faulting mechanisms and stress regime at the European HDR site of Soultz-sous-Forêts, France[J]. Geothermics, 2006, 35(5/6):561-575. DOI URL
[20]	KURIYAGAWA M, TENMA N. Development of hot dry rock technology at the Hijiori test site[J]. Geothermics, 1999, 28(4/5):627-636. DOI URL
[21]	BACHMANN C E, WIEMER S, WOESSNER J, et al. Statistical analysis of the induced Basel 2006 earthquake sequence: introducing a probability-based monitoring approach for Enhanced Geothermal Systems[J]. Geophysical Journal International, 2011, 186(2):793-807. DOI URL
[22]	KIM K H, REE J H, KIM Y, et al. Assessing whether the 2017 Mw 5.4 Pohang earthquake in South Korea was an induced event[J]. Science, 2018, 360:1007-1009. DOI URL
[23]	GRIGOLI F, CESCA S, RINALDI A P, et al. The November 2017 Mw 5.5 Pohang earthquake: a possible case of induced seismicity in South Korea[J]. Science, 2018, 360:1003-1006. DOI URL
[24]	SCHILL E, GENTER A, CUENOT N, et al. Hydraulic performance history at the Soultz EGS reservoirs from stimulation and long-term circulation tests[J]. Geothermics, 2017, 70:110-124. DOI URL
[25]	薛建球, 甘斌, 李百祥, 等. 青海共和—贵德盆地增强型地热系统 (干热岩) 地质-地球物理特征[J]. 物探与化探, 2013, 37(1):35-41.
[26]	严维德, 王焰新, 高学忠, 等. 共和盆地地热能分布特征与聚集机制分析[J]. 西北地质, 2013, 46(4):223-230.
[27]	蔺文静, 王凤元, 甘浩男, 等. 福建漳州干热岩资源选址与开发前景分析[J]. 科技导报, 2015, 33(19):28-34.
[28]	王波. 首口干热岩超深探采井在郑州开钻[J]. 能源研究与信息, 2016, 32(2):70.
[29]	张前, 吴小洁, 谢顺胜, 等. 综合物探方法在海南陵水地区干热岩资源勘查中的应用[J]. 工程地球物理学报, 2015, 12(4):477-483.
[30]	王贵玲, 蔺文静. 干热岩开发的破冰之秘[J]. 国土资源科普与文化, 2018(1):22-27.
[31]	JUNG R, . EGS: goodbye or back to the future[M/OL]//Effective and sustainable hydraulic fracturing, 2013:95-121 [2019-06-01]. https://doi.org/10.5772/56458
[32]	TOMAC I, SAUTER M. A review on challenges in the assessment of geomechanical rock performance for deep geothermal reservoir development[J]. Renewable and Sustainable Energy Reviews, 2018, 82(3):3972-3980. DOI URL
[33]	黄荣撙. 水力压裂裂缝的起裂和扩展[J]. 石油勘探与开发, 1982, 9(5):62-74.
[34]	刘建军, 冯夏庭, 裴桂红. 水力压裂三维数学模型研究[J]. 岩石力学与工程学报, 2003, 22(12):2042-2046.
[35]	张东晓, 杨婷云. 页岩气开发综述[J]. 石油学报, 2013, 34(4):792-801.
[36]	冯彦军, 康红普. 水力压裂起裂与扩展分析[J]. 岩石力学与工程学报, 2013(增刊2):3169-3179.
[37]	OLASOLO P, JUAREZ M C, MORALES M P, et al. Enhanced geothermal systems (EGS): a review[J]. Renewable and Sustainable Energy Reviews, 2016, 56:133-144. DOI URL
[38]	唐春安, 赵坚, 王思敬. 基于开挖技术的增强型地热系统:EGS-E概念模型[J]. 岩石力学与工程动态, 2018(1):49-53.
[39]	TANG M, LI H, TANG C A. Study on preliminarily estimating performance of elementary deep underground engineering structures in future large-scale heat mining projects[J]. Geofluids, 2019(4):1-10.
[40]	ZHAO J, TANG C A, WANG S J. Excavation based enhanced geothermal system (EGS-E): introduction to a new concept[J]. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2020, 6:6. DOI URL
[41]	刘健, 刘泽功, 高魁, 等. 不同装药模式爆破载荷作用下煤层裂隙扩展特征试验研究[J]. 岩石力学与工程学报, 2016, 35(4):735-742.
[42]	严成增, 孙冠华, 郑宏, 等. 爆炸气体驱动下岩体破裂的有限元-离散元模拟[J]. 岩土力学, 2015, 36(8):2419-2425.
[43]	高金石, 杨军, 张继春. 准静态压力作用下岩体爆破成缝方向与机理的研究[J]. 爆炸与冲击, 1990, 10(1):76-84.
[44]	来兴平, 崔峰, 曹建涛, 等. 特厚煤体爆破致裂机制及分区破坏的数值模拟[J]. 煤炭学报, 2014, 39(8):1642-1649.
[45]	李连崇, 唐春安, CAI M. 自然崩落法采矿矿岩崩落过程数值模拟研究[J]. 金属矿山, 2011(12):13-17.
[46]	SANYAL S K, MORROW J W, BUTLER S J, et al. Is EGS commercially feasible?[J]. Geothermal Resources Council Transactions, 2007, 31:313-322.
[47]	TENZER H. Development of hot dry rock technology[J]. Geo-Heat Center Quarterly Bulletin, 2001, 4(22):14-18.
[48]	WARNER N R, CHRISTIE C A, JACKSON R B, et al. Impacts of shale gas wastewater disposal on water quality in western Pennsylvania[J]. Environmental Science and Technology, 2013, 47(20):11849-11857. DOI URL
[49]	MYERS T. Potential contaminant pathways from hydraulically fractured shale to aquifers[J]. Groundwater, 2012, 50(6):872-882. DOI URL
[50]	谢和平, 高峰, 鞠杨, 等. 深地煤炭资源流态化开采理论与技术构想[J]. 煤炭学报, 2017, 42(3):547-556.
[51]	DURRHEIM R J, OGASAWARA H, NAKATANI M, et al. Observational studies in South African mines to mitigate seismic risks: challenges and achievements[J]. Rock Mechanics, 2017, 3:14.
[52]	何满潮. 深部软岩工程的研究进展与挑战[J]. 煤炭学报, 2014, 39(8):1409-1417.
[53]	谢和平, 高峰, 鞠杨, 等. 深地科学领域的若干颠覆性技术构想和研究方向[J]. 工程科学与技术, 2017(1):1-8.
[54]	习近平. 为建设世界科技强国而奋斗:在全国科技创新大会、两院院士大会、中国科协第九次全国代表大会上的讲话[J]. 中国应急管理, 2016(6):4-9.
[55]	CAI M F, BROWN E T. Challenges in the mining and utilization of deep mineral resources[J]. Engineering, 2017, 3(4):432-433. DOI URL