Influencing factors of thermal conductivity of cementing materials for geothermal wells

ZHANG Hao1,2 XU Shuanhai2 YANG Yu1,2 HAN Yongliang2 ZHANG Weidong2 LI Yongqiang1,2

(1.China Coal Research Institute, Beijing 100013)
(2.Xi’an Research Institute Co., Ltd., China Coal Technology and Engineering Group Corp., Xi’an, Shaanxi Province, China 710077)

【Abstract】The thermal conductivity of cementing materials is one of the factors that affect the heat removal effect of geothermal wells. To improve the thermal conductivity of cementing materials for geothermal wells, we conducted orthogonal tests to study the thermal conductivity of cementing materials based on the AHP-CRITIC hybrid weighting method and range analysis. The results show that the thermal conductivity of cementing materials can be improved by adding natural flake graphite, iron powder and quartz sand. The content of graphite and the water-to-solid ratio are the primary and secondary factors that affect the comprehensive properties of cementing materials. With the increase in graphite content, thermal conductivity, 48 h compressive strength and fluidity decreased. The results show that the optimal mix ratio of high-thermal-conductivity cementing materials is as follows: Water-to-solid ratio is 0.44; the amount of graphite, iron powder and quartz sand accounted for 7.5%, 3%, and 2% of the cement mass, respectively; its thermal conductivity can reach 1.87 W/(m·K), which is about 70% higher than conventional cementing materials. It can provide reference for efficient development and utilization of geothermal energy.

【Keywords】 geothermal energy; cementing material; thermal conductivity; orthogonal test; AHP-CRITIC hybrid weighting method; range analysis;

【DOI】

【Funds】 Science and Technology Innovation Fund Key Project of Tiandi Science and Technology Co., Ltd. (2018TDZD017) Science and Technology Innovation Fund of Xi’an Research Institute of CCTEG (2018XAYZD13)

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    References

    [1] WANG Kai, YUAN Bin, JI Guomin, et al. A comprehensive review of geothermal energy extraction, and utilization in oilfields [J]. Journal of Petroleum Science and Engineering, 2018, 168: 465–477.

    [2] DUO Ji. Drilling dry hot rock to promote geothermal power generation [J]. Science & Technology Review, 2015, 33 (19): 1 (in Chinese).

    [3] China Geologic Survey, et al. China geothermal energy development report [R]. Beijing: China Petrochemical Press, 2018 (in Chinese).

    [4] WANG Guiling, ZHANG Wei, LIANG Jiyun, et al. Evaluation of geothermal resources potential in China [J]. Acta Geoscientica Sinica, 2017, 38 (4): 449–459 (in Chinese).

    [5] ZHANG Mingchang. Cementing technology [M]. Beijing: China Petrochemical Press, 2016.

    [6] YANG Shiming, TAO Wenquan. Heat transfer [M]. Beijing: Higher Education Press, 2006 (in Chinese).

    [7] KOHL T, SALTON M, RYBACH L. Data analysis of the deep borehole heat exchanger plant Weissbad (Switzerland) [C]. //Proceedings World Geothermal Congress. Kyushu, Japan: ResearchGate, 2000: 3459–3464.

    [8] LI Ruixia, WANG Gaosheng, SONG Xianzhi, et al. Numerical analysis of the effect of cement sheath on the heat extraction performance of coaxial borehole heat exchangers geothermal system [J]. Building Science, 2018, 34 (4): 36–40 (in Chinese).

    [9] LIU Chongjian, HUANG Baizong, XU Tongtai, et al. Theory and application of cementing for oil & gas well [M]. Beijing: Petroleum Industry Press, 2001 (in Chinese).

    [10] QI Fengzhong, LIU Shuoqiong, SHEN Jiyun. Suggestion onCNPC cementing technological development [J]. Oil Forum, 2017, 36 (1): 26–31 (in Chinese).

    [11] DING Shidong, TAO Qian, MALanrong. Progress, outlook, and the development directions at Sinopec in cementing technology progress [J]. Petroleum Drilling Techniques, 2019, 47 (3): 41–49 (in Chinese).

    [12] WANG Chufeng, WANG Ruihe, YANG Huanqiang, et al. Cementing technology of foam cement slurry for coalbed methane well and its application [J]. Coal Geology & Exploration, 2016, 44 (2): 116–120 (in Chinese).

    [13] CHEN Chun, QIAN Chunxiang, CHEN Huisu, et al. Model study of thermal conductivity of cement based thermal insulation materials [J]. Journal of Building Materials, 2009, 12 (3): 348–351 (in Chinese).

    [14] ZHANG Weiping, TONG Fei, XING Yishan, et al. An investigation of thermal conductivity of cement-based composites with multi-scale micromechanical method [J]. Journal of Building Materials, 2015, 18 (2): 183–189 (in Chinese).

    [15] ZHAO Yu. Mesosopic numerical simulation and engineering application of high thermal conductivity concrete [D]. Xi’an: Chang’an University, 2017 (in Chinese).

    [16] ZHOU Shiming, LI Gensheng, WANG Qichun. Research and preparation of ultra-heavy slurry [J]. Petroleum Exploration and Development, 2013, 40 (1): 107–110 (in Chinese).

    [17] YUAN Shen. Research on high density cement slurry system [D]. Qingdao: China University of Petroleum (East China), 2013 (in Chinese).

    [18] LIU Jingyan, ZHANG Ke, WANG Guihua. Comparative study on data standardization methods in comprehensive evaluation [J]. Digital Technology & Application, 2018, 36 (6): 84–85 (in Chinese).

This Article

ISSN:1001-1986

CN: 61-1155/P

Vol 48, No. 02, Pages 195-201

April 2020

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Article Outline

Abstract

  • 1 Test program
  • 2 Test results and discussion
  • 3 Conclusions
  • References