Numerical simulation and analysis of geothermal rock mass heat flow coupling based on fracture roughness characterization method

doi:10.11949/0438-1157.20221552

Abstract

Abstract:

With the transformation of energy structure, geothermal energy like dry hot rock has been rapidly developed. As the complex composite of the internal structure of the geothermal rock, as well as the changeable transfusion and heat transfer process, further discussion is needed as to how to establish a more accurate representation model and conduct multi-physical fields coupling analysis aiming at the distribution characteristics of rock fracture. Based on the description method of joint roughness coefficient (JRC), the representative elementary volume (REV) was introduced into the JRC size selection and it was applied into the geothermal rock physical model. The coupling analysis was conducted on the temperature field of geothermal rock and transfusion field by adopting numerical simulation method. It was found that the distribution of temperature field near the fracture was basically consistent with the fracture's morphology, showing a fluctuation law of the temperature field of bedrock with the change of the fracture morphology. There was a negative correlation between fluid injection speed and temperature on the time when the system reached steady state; both lower injection speed and higher injection temperature could effectively prolong the production life of the system; in addition, through the analysis of the outlet normal heat flux, it was concluded that the optimal injection velocity in this paper.

Key words: geothermal, JRC, representative elementary volume, heat transferr, transport processes, numerical simulation

摘要：

随着能源结构转型，干热岩等地热岩体得到了快速发展。地热岩体内部结构组成复杂，渗流与传热过程多变，如何针对岩体裂隙分布特征，建立更加精准的描述表征模型并进行多物理场耦合分析，有待深入探讨。基于裂隙粗糙性表征（joint roughness coefficient，JRC）描述方法，将表征单元体（representative elementary volume，REV）引入到JRC尺寸选取中，并将其应用于地热岩体物理模型中，采用数值模拟方法，对地热岩体温度场与渗流场进行了耦合分析。研究发现，裂隙附近温度场分布与裂隙的形态基本一致，表现出一种基岩温度场随着裂隙形态变化的波动性规律；流体注入速度和温度对系统运行达到稳态的时间影响呈负相关性；较低的注入速度和较高的注入温度都可以有效延长系统生产寿命，此外，通过对出口法向热通量的分析得出最佳注入流速。

关键词: 地热, JRC, 表征单元体, 传热, 传递过程, 数值模拟

CLC Number:

TK 529

Zhiguo WANG, Meng XUE, Yushuang DONG, Tianzhen ZHANG, Xiaokai QIN, Qiang HAN. Numerical simulation and analysis of geothermal rock mass heat flow coupling based on fracture roughness characterization method[J]. CIESC Journal, 2023, 74(S1): 223-234.

王志国, 薛孟, 董芋双, 张田震, 秦晓凯, 韩强. 基于裂隙粗糙性表征方法的地热岩体热流耦合数值模拟与分析[J]. 化工学报, 2023, 74(S1): 223-234.

Figures/Tables 17

Fig.1 Schematic diagram of crack roughness characterization based on JRC

Fig.2 Representation diagram of JRC value varying with feature size based on REV scale

Fig.3 The typical roughness curves of JRC (8—10, 10—12) selected based on RVE digitized

Fig.4 Physical model and two-dimensional conceptual model of hot and dry rock based on JRC characterization at REV scale

Table 1 Physical parameters of fractured rock mass

介质

密度ρ/(kg/m³)

热导率λ/

(W/(m·K))

比热容C/

(J/(kg·K))

动力黏度

μ/(Pa·s)

Fig.5 Finite element model grid

Fig.6 Verification of simulation results

Fig.7 Cloud image of model temperature distribution field (vin=0.04 m/s)

Fig.8 Model temperature contour map (vin=0.04 m/s)

Fig.9 The average temperature of outlet fluid changes with time at different flow rates

Fig.10 Time variation diagram of average temperature at outlet with different roughness

Fig.11 System life as a function of fluid injection rate

Fig.12 Figure of average rock mass temperature and fluid outlet temperature change in steady state

Fig.13 Change of outlet normal heat flux under different injection velocity in steady state

Fig.14 Time variation of average horizontal temperature at crack outlet at different injection temperatures

Fig.15 System life as a function of fluid injection temperature

Fig.16 Comparison between average rock mass temperature and average fluid outlet temperature in steady state

References 37

1	黄璜, 刘然, 李茜, 等. 地热能多级利用技术综述[J]. 热力发电, 2021, 50(9): 1-10.
	Huang H, Liu R, Li Q, et al. Overview on multi-level utilization techniques of geothermal energy[J]. Thermal Power Generation, 2021, 50(9): 1-10.
2	黄文博, 曹文炅, 李庭樑, 等. 干热岩热能重力热管采热系统数值模拟研究与经济性分析[J]. 化工学报, 2021, 72(3): 1302-1313.
	Huang W B, Cao W J, Li T L, et al. Numerical study and economic analysis of gravity heat pipe hot dry rock geothermal system[J]. CIESC Journal, 2021, 72(3): 1302-1313.
3	王贵玲, 刘彦广, 朱喜, 等. 中国地热资源现状及发展趋势[J]. 地学前缘, 2020, 27(1): 1-9.
	Wang G L, Liu Y G, Zhu X, et al. The status and development trend of geothermal resources in China[J]. Earth Science Frontiers, 2020, 27(1): 1-9.
4	刘润川, 任战利, 叶汉青, 等. 地热资源潜力评价: 以鄂尔多斯盆地部分地级市和重点层位为例[J]. 地质通报, 2021, 40(4): 565-576.
	Liu R C, Ren Z L, Ye H Q, et al. Potential evaluation of geothermal resources: exemplifying some municipalities and key strata in Ordos Basin as a study case[J]. Geological Bulletin of China, 2021, 40(4): 565-576.
5	何淼, 龚武镇, 许明标, 等. 干热岩开发技术研究现状与展望分析[J]. 可再生能源, 2021, 39(11): 1447-1454.
	He M, Gong W Z, Xu M B, et al. Research status and prospect analysis of hot dry rock development technology[J]. Renewable Energy Resources, 2021, 39(11): 1447-1454.
6	陆川, 王贵玲. 干热岩研究现状与展望[J]. 科技导报, 2015, 33(19): 13-21.
	Lu C, Wang G L. Current status and prospect of hot dry rock research[J]. Science ＆ Technology Review, 2015, 33(19): 13-21.
7	肖鹏, 窦斌, 田红, 等. 开采海洋区域干热岩的可行性探讨[J]. 海洋地质前沿, 2018, 34(8): 55-60.
	Xiao P, Dou B, Tian H, et al. Feasibility of exploitation of submarine hot dry rock in offshore area[J]. Marine Geology Frontiers, 2018, 34(8): 55-60.
8	杨冶, 姜志海, 岳建华, 等. 干热岩勘探过程中地球物理方法技术应用探讨[J]. 地球物理学进展, 2019, 34(4): 1556-1567.
	Yang Y, Jiang Z H, Yue J H, et al. Discussion on application of geophysical methods in hot dry rock (HDR) exploration[J]. Progress in Geophysics, 2019, 34(4): 1556-1567.
9	Grant M A, Bixley P F. Geothermal Reservoir Engineering[M]. 2nd ed. Burlington, MA: Academic Press, 2011.
10	蔺文静, 刘志明, 马峰, 等. 我国陆区干热岩资源潜力估算[J]. 地球学报, 2012, 33(5): 807-811.
	Lin W J, Liu Z M, Ma F, et al. An estimation of HDR resources in China's mainland[J]. Acta Geoscientica Sinica, 2012, 33(5): 807-811.
11	Xu T, Hu Z, Li S, et al. Enhanced geothermal system: international progresses and research status of China[J]. Acta Geologica Sinica, 2018, 92(9): 1936-1947.
12	肖鹏, 闫飞飞, 窦斌, 等. 增强型地热系统水平井平行多裂隙换热过程数值模拟[J]. 可再生能源, 2019, 37(7): 1091-1099.
	Xiao P, Yan F F, Dou B, et al. Numerical simulation on the heat transfer process of parallel multi-fractures in enhanced geothermal system horizontal well[J]. Renewable Energy Resources, 2019, 37(7): 1091-1099.
13	甘浩男, 王贵玲, 蔺文静, 等. 增强型地热系统环境地质影响现状研究与对策建议[J]. 地质力学学报, 2020, 26(2): 211-220.
	Gan H N, Wang G L, Lin W J, et al. Research on the status quo of environmental geology impact of enhanced geothermal system and countermeasures[J]. Journal of Geomechanics, 2020, 26(2): 211-220.
14	翟海珍, 苏正, 凌璐璐, 等. 平行多裂隙模型中换热单元体对EGS釆热的影响[J]. 地球物理学进展, 2016, 31(3): 1399-1405.
	Zhai H Z, Su Z, Ling L L, et al. Impact of heat transfer unit on EGS heat extraction in the multi-parallel fracture model[J]. Progress in Geophysics, 2016, 31(3): 1399-1405.
15	张万鹏. 用近接型相似微小地震对判明干热岩热储层主要裂隙方位的研究[D]. 焦作: 河南理工大学, 2012.
	Zhang W P. The azimuth determination research of the main fractures in hot dry rock reservoir by proximity similar microseismic doublets[D]. Jiaozuo: Henan Polytechnic University, 2012.
16	Glassley W E. Geothermal Energy: Renewable Energy and the Environment[M]. 2nd ed. Boca Raton: CRC Press, 2014.
17	Barton N. Review of a new shear-strength criterion for rock joints[J]. Engineering Geology, 1973, 7(4): 287-332.
18	Barton N, Choubey V. The shear strength of rock joints in theory and practice[J]. Rock Mechanics, 1977, 10(1): 1-54.
19	Cruden D M. International society for rock mechanics commission on standardization of laboratory and field tests[J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1978, 15(6): 319-368.
20	Tse R, Cruden D M. Estimating joint roughness coefficients[J]. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 1979, 16(5): 303-307.
21	Yang Z Y, Lo S C, Di C C. Reassessing the joint roughness coefficient (JRC) estimation using Z₂ [J]. Rock Mechanics and Rock Engineering, 2001, 34(3): 243-251.
22	Zhang G C, Karakus M, Tang H M, et al. A new method estimating the 2D joint roughness cofficient for discontinuity surfaces in rock masses[J]. International Journal of Rock Mechanics and Mining Sciences, 2014, 72: 191-198.
23	王如宾, 柴军瑞. 单裂隙水流作用下岩体稳定温度场理论模型与有限元数值模拟[J]. 水利水电技术, 2006, 37(9): 17-19.
	Wang R B, Chai J R. Theoretical model of rock mass steady temperature field under single fissure flow and numerical simulation with finite element method[J]. Water Resources and Hydropower Engineering, 2006, 37(9): 17-19.
24	孙致学, 徐轶, 吕抒桓, 等. 增强型地热系统热流固耦合模型及数值模拟[J]. 中国石油大学学报(自然科学版), 2016, 40(6): 109-117.
	Sun Z X, Xu Y, Lv S H, et al. A thermo-hydro-mechanical coupling model for numerical simulation of enhanced geothermal systems[J]. Journal of China University of Petroleum (Edition of Natural Science), 2016, 40(6): 109-117.
25	张驰. 干热岩单裂隙渗流—传热实验与数值模拟研究[D]. 长春: 吉林大学, 2017.
	Zhang C. Experiment and numerical study of seepage heat transfer in a single fracture of hot dry rock[D]. Changchun: Jilin University, 2017.
26	Ma Y Q, Zhang Y J, Hu Z J, et al. Numerical investigation of heat transfer performance of water flowing through a reservoir with two intersecting fractures[J]. Renewable Energy, 2020, 153: 93-107.
27	Lu W Y, He C C. Numerical simulation on the simultaneous stress interference of parallel multiple hydraulic fractures[J]. Energy Exploration & Exploitation, 2021, 39(4): 1143-1161.
28	Huang Y B, Zhang Y J, Yu Z W, et al. Experimental investigation of seepage and heat transfer in rough fractures for enhanced geothermal systems[J]. Renewable Energy, 2019, 135: 846-855.
29	Auradou H. Influence of wall roughness on the geometrical, mechanical and transport properties of single fractures[J]. Journal of Physics D: Applied Physics, 2009, 42(21): 214015.
30	高雪峰, 张延军, 黄奕斌, 等. 花岗岩粗糙单裂隙对流换热特性的数值模拟[J]. 岩土力学, 2020, 41(5): 1761-1769.
	Gao X F, Zhang Y J, Huang Y B, et al. Numerical simulation of the convective heat transfer characteristics of a rough single fracture in granite[J]. Rock and Soil Mechanics, 2020, 41(5): 1761-1769.
31	甘磊, 马洪影, 沈振中. 下凹形态裂隙面粗糙程度表征及立方定律修正系数拟合[J]. 水利学报, 2021, 52(4): 420-431.
	Gan L, MAH Y, Shen Z Z. Roughness characterization of concave fracture surface and coefficient fitting of modified cubic law[J]. Journal of Hydraulic Engineering, 2021, 52(4): 420-431.
32	杜时贵, 郭霄. 岩体结构面粗糙度系数JRC的研究现状[J]. 水文地质工程地质, 2003, 30(S1): 30-33.
	Du S G, Guo X. Recent development of the joint roughness coefficient (JRC)[J]. Hydrogeology and Engineering Geology, 2003, 30(S1): 30-33.
33	李锐, 肖维民. 基于Barton标准剖面线精细数字化处理的岩石节理JRC计算新公式研究[J]. 岩石力学与工程学报, 2018, 37(S1): 3515-3522.
	Li R, Xiao W M. Study on a new equation for calculating JRC based on fine digitization of standard profiles proposed by Barton[J]. Chinese Journal of Rock Mechanics and Engineering, 2018, 37(S1): 3515-3522.
34	杨凯, 林木景, 王晨龙, 等. 岩石节理轮廓线的数字表征方法影响研究[J]. 太原理工大学学报, 2021, 52(5): 797-802.
	Yang K, Lin M J, Wang C L, et al. Research on the influence of digital characterization of rock joint contour[J]. Journal of Taiyuan University of Technology, 2021, 52(5): 797-802.
35	王志国, 冯艳, 杨文哲, 等. 基于REV的孔隙型多孔介质导热分析模型[J]. 化工学报, 2020, 71(S2): 118-126.
	Wang Z G, Feng Y, Yang W Z, et al. Thermal conductivity analysis model of porous media based on REV[J]. CIESC Journal, 2020, 71(S2): 118-126.
36	康健, 赵明鹏, 赵阳升, 等. 随机介质固热耦合模型与高温岩体地热开发人工储留层二次破裂数值模拟[J]. 岩石力学与工程学报, 2005, 24(6): 969-974.
	Kang J, Zhao M P, Zhao Y S, et al. Random non-homogeneous solid-heat coupled model and numerical simulations ofsecond fracturing for man-made-reserve stratum in hdr[J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(6): 969-974.
37	曾玉超, 苏正, 吴能友, 等. 增强型地热系统储层试验与性能特征研究进展[J]. 矿业研究与开发, 2012, 32(3): 22-27, 63.
	Zeng Y C, Su Z, Wu N Y, et al. Advances in reservoir test and performance characteristics of enhanced geothermal system[J]. Mining Research and Development, 2012, 32(3): 22-27, 63.

[1]	Juhui CHEN, Tong SU, Dan LI, Liwei CHEN, Wensheng LYU, Fanqi MENG. Study on the heat transfer characteristics of microchannels under the action of fin-shaped spoilers [J]. CIESC Journal, 2024, 75(9): 3122-3132.
[2]	Shuyue LI, Huan WANG, Shaoqiang ZHOU, Zhihong MAO, Yongmin ZHANG, Junwu WANG, Xiuhua WU. Numerical simulation of hydrogen reduction of U₃O₈ in fluidized bed reactors using CPFD method [J]. CIESC Journal, 2024, 75(9): 3133-3151.
[3]	Shaojun DOU, Liang HAO. Mesoscale simulation of coupled gas charge transfer process in PEMFC catalyst layer [J]. CIESC Journal, 2024, 75(8): 3002-3010.
[4]	Xiaoyu QIAN, Xuan RUAN, Shuiqing LI. Structural reconstruction and levitation of dielectric particle layers in electric fields [J]. CIESC Journal, 2024, 75(8): 2756-2762.
[5]	Ziliang ZHU, Shuang WANG, Yu'ang JIANG, Mei LIN, Qiuwang WANG. Solid-liquid phase change algorithm with Euler-Lagrange iteration [J]. CIESC Journal, 2024, 75(8): 2763-2776.
[6]	Aiming DENG, Yurong HE, Tianqi TANG, Yanwei HU. Simulation of effect of draft plate on particle growth process in spray fluidized beds [J]. CIESC Journal, 2024, 75(8): 2787-2799.
[7]	Zhenghang LUO, Jingyu LI, Weixiong CHEN, Daotong CHONG, Junjie YAN. Numerical simulation of heat transfer characteristic and bubble force analysis of low flow rate vapor condensation under rolling motion [J]. CIESC Journal, 2024, 75(8): 2800-2811.
[8]	Hu JIN, Fan YANG, Mengyao DAI. The motion process of a droplet on a circular cylinder based on the lattice Boltzmann method [J]. CIESC Journal, 2024, 75(8): 2897-2908.
[9]	Lichang FANG, Zilong LI, Bo CHEN, Zheng SU, Lisi JIA, Zhibin WANG, Ying CHEN. Study on cooling characteristics of chip array based on microencapsulated phase change material slurry [J]. CIESC Journal, 2024, 75(7): 2455-2464.
[10]	Zhimin HAN, Jiang LI, Zeqi CHEN, Wei LIU, Zhiming XU. Particulate fouling characteristics of different longitudinal vortex generators in pulsating flow channel [J]. CIESC Journal, 2024, 75(7): 2486-2496.
[11]	Fei LU, Bona LU, Guangwen XU. Analysis of criteria for ideal flow patterns in gas-solid micro fluidized bed reaction analyzer [J]. CIESC Journal, 2024, 75(6): 2201-2213.
[12]	Bin HUANG, Shengjie FENG, Cheng FU, Wei ZHANG. Numerical study on spreading characteristics of droplet impact on single fiber [J]. CIESC Journal, 2024, 75(6): 2233-2242.
[13]	Jinshan WANG, Shixue WANG, Yu ZHU. Influence of cooling surface temperature difference on the high temperature proton-exchange membrane fuel cell performance [J]. CIESC Journal, 2024, 75(5): 2026-2035.
[14]	Yifei LI, Xinyu DONG, Weishu WANG, Lu LIU, Yifan ZHAO. Numerical study on heat transfer of dry ice sublimation spray cooling on the surface of micro-ribbed plate [J]. CIESC Journal, 2024, 75(5): 1830-1842.
[15]	Fan LIU, Yuantong ZHANG, Cheng TAO, Chengyu HU, Xiaoping YANG, Jinjia WEI. Performance of manifold microchannel liquid cooling [J]. CIESC Journal, 2024, 75(5): 1777-1786.