Effect of thermally conductive filler on thermal conductivity of cementing materials in geothermal wells

Authors

YANG Yu, China Coal Research Institute, Beijing 100013, China; Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710078, China
XU Shuanhai, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710078, China
ZHANG Hao, China Coal Research Institute, Beijing 100013, China; Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710078, China
HAN Yongliang, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710078, China
ZHANG Weidong, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710078, China

Abstract

Adding heat-conducting filler to the cement of the geothermal well could significantly improve the thermal conductivity of the cement stone and enhance the heat extraction effect of the geothermal well. In this study, on the basis of summarizing the heat conduction path theory and concept of high packing density, the effects of different filler types, particle sizes and dosages on the thermal conductivity of cementing cement were investigated through experiments. The test results showed that graphite had the best effect on improving the thermal conductivity of cement stone compared to other types of filler; the larger the graphite particle size, the higher the thermal conductivity of cement stone. The mixing of graphite with different particle sizes had a better effect on improving the thermal conductivity of cement stone than graphite with a single particle size. The optimal mixing formula was: graphite particle size was 150 μm and 100 μm, and the mass ratio was 2：1. With the increase of graphite content, the thermal conductivity of cementing materials increased, and the fluidity and compressive strength of 48 h gradually decreased. According to the relevant cementing specifications, the graphite content in the cementing materials should be controlled at about 9%. The research will provide references for the preparation of high thermal conductivity cementing materials for geothermal wells.

Keywords

geothermal energy, thermally conductive filler, cementing materials, thermal conductivity, heat conduction path theory, compact packing theory

DOI

10.3969/j.issn.1001-1986.2020.05.022

Recommended Citation

YANG Yu, XU Shuanhai, ZHANG Hao, et al. (2020) "Effect of thermally conductive filler on thermal conductivity of cementing materials in geothermal wells," Coal Geology & Exploration: Vol. 48: Iss. 5, Article 23.
DOI: 10.3969/j.issn.1001-1986.2020.05.022
Available at: https://cge.researchcommons.org/journal/vol48/iss5/23

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