Investigation of consolidation/thermal insulation property and mechanism of casing cement in the heat-insulating section of geothermal production well

ABSTRACT

In the process of geothermal exploitation, heat loss often occurs in the heat-insulating section of the production well, resulting in a decrease in heat extraction efficiency. However, there have been few studies on thermal insulation cement for geothermal well, lacking complete engineering application properties evaluation. In view of this, a new type of thermal insulation composite cement was successfully developed by incorporating thermal insulation filler (Hollow glass beads, HGB), heat stabilizing material (SiO₂) and additives. The engineering application properties were evaluated using standardized methods, and the results demonstrated excellent rheology and stability of the cement slurry. The 14d compressive strength of the cement stone reached 21.24 MPa, and the thermal conductivity remained stable at 0.1535 W/(m·K). Finally, the consolidation/thermal insulation mechanism of the material was investigated. Analysis showed that the secondary hydration of SiO₂ could generate more C-S-H, and additives could regulate the hydration reaction of slurry. The excellent thermal insulation property of material was derived from interface lattice scattering, the low thermal conductivity of HGB, and the gas heat-conduction recession within HGB. The study results provide a new idea to solve the problem of heat loss of geothermal production well from the perspective of material development.

KEYWORDS:

• Geothermal exploitation
• thermal insulation cement
• thermal conductivity
• consolidation/Thermal insulation property
• thermal insulation mechanism

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This paper has been supported by the National Natural Science of China (Grant No. 42072339 and U19A2097), the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Grant No. SKLGP2022Z006) and Everest Technology Research Proposal of Chengdu University of Technology (Grant No. 80000-2020ZF11411).

Notes on contributors

Yujie Li

Yujie Li, a master of geological engineering at Chengdu University of Technology.

Sheng Wang

Sheng Wang, the professor of Geological Engineering, Doctoral Supervisor, Chengdu University of Technology.

Xin He

Xin He, a master of geological engineering in Chengdu University of Technology.

Jie Xiang

Jie Xiang, a master of geological engineering in Chengdu University of Technology.