High temperature cement compositions for use downhole

摘要

In a process to design high temperature cement slurries, temperature stable mineral phases (such as anorthite and wairakite) are selected that will form at the downhole temperature of the well. Aluminium modifiers and silica oxides are added to the dry cement so that the elemental composition of the blend corresponds to the mineral phases selected. The control of the particle size distribution and the relative amount of those minerals allow their addition at high concentration while leaving the slurry easily mixable and pumpable. The kinetics that affect how quickly the thermodynamic equilibrium of the targeted mineral phases formation is reached, can be influenced by adjusting the crystallinity and the particle sizes of the different solids.