Physical properties of G-class cement for geothermal well cementing in South Korea. (August 2015)

• Record Type: Journal Article
• Authors: Won, Jongmuk; Lee, Dongseop; Na, Kyunguk; Lee, In-Mo; Choi, Hangseok
• Is Part Of: Renewable energy. Volume 80(2015)
• Page Start: 123
• Page End: 131
• Publication Date: 2015-08
• Subjects: Geothermal well cementing -- G-class cement -- Groutability -- Uniaxial compressive strength -- Thermal conductivity -- Free fluid content; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2015.01.067
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: The cement material adopted for a new geothermal well project in South Korea is specialized as the G-class cement, which is commonly used in the oil-well industry, and regulated by the API (American Petroleum Institute). In order to maintain the optimal generating performance of geothermal wells, physical properties of the cementing material should be satisfactory. In this paper, the significant material properties (i.e., groutability, uniaxial compressive strength, thermal conductivity, bleeding potential, phenolphthalein indication) of the G-class cement were experimentally examined, with consideration of various water–cement (w/c) ratios as mix proportion. Important findings through the experiments are as follows; (1) Groutability of the G-class cement increases with the addition of a small amount of retarder. (2) There would be a structural problem when the w/c ratio is kept extremely high in order to obtain acceptable groutability. (3) Thermal conductivity of the G-class cement is small enough to prevent heat loss during circulating up hot steam or water from the deep underground to the ground surface. (4) The G-class cement used for geothermal-well cementing causes no bleeding problem. (5) The phenolphthalein indicator is applicable to distinguishing the G-class cement from the drilling mud. Highlights: Groutability of G-class cement increases with addition of a small amount of retarder. The optimum retarder–cement ratio is recommended between 0.01 and 0.015. The water–cement ratios of 0.55, 0.6, 0.7, and 0.8 will not cause structural problems. Thermal conductivity of G-class cement decreases with the water–cement ratio. The G-class cement for geothermal-well causes no bleeding problem.