Strength Development of 2CaO/SiO2-Silica Cement Under High-Temperature and High-Pressure Conditions

Abstract

Summary To cement deep oil wells and high-temperature geothermal wells, special cements with superior cementing properties, hardening characteristics, and durability under high-temperature and high-pressure conditions are required. Therefore, we have been accumulating technical data on a special cement consisting of 2CaO/SiO2 and silica. In this paper, strength development at 290 to 842°F [143 to 450°C] was investigated for the mixtures of three 2CaO/SiO2 modifications (γ, β, and α′) and quartz. Various analyses were carried out on hardened specimens, and the mechanism of hydrothermal reaction for these mixtures is discussed. Within the limits of this experiment, we conclude that the strength of 2CaO/SiO2-quartz mixtures depends on 2CaO/SiO2 modifications, curing temperature, and curing time, but the influences of curing pressure and increasing rate of temperature are relatively minor. Moreover, we assume that the difference of reaction rate of 2CaO/SiO2 and quartz, the type of hydration products, and the producing conditions will result in the difference of strength, depending on 2CaO/SiO2 modification.