Study of High Temperature Silicate Cement Slurry

Conventional silicate cements at elevated temperatures have a series of problems, such as poor stability, declining of compressive strengthof set cement and cracking of set cement etc. To address these problems, studies have been conducted on the selection of materials for modification of cement, optimization of the mechanical properties of set cement and the overall properties od modified silicate cement slurry. It was concluded that, at elevated temperatures, addition of highly active minerals (such as volcanic ash) into cement can ensure the sound development of the compressive strength of set cement. Crystal whiskers/fibers selected play an important role in the "brittleness reduction and toughness enhancement" of set cement, ensuring that set cement does not crack when curing at elevated temperatures and its elastic modulus is controlled to less than 9.0 GPa. Using high performance filter loss reducers, retarders and high temperature stabilizers suitable for the cement, the cement slurry will have good overall properties, i.e., low filter loss, good high temperature stability, thickening time that is controllable and short transit time etc. This study is of importance to safe cementing of deep and ultra-deep wells with high job quality.