Preparation, properties and hydration process of low temperature nano-composite cement slurry

Abstract

Abstract In the process of drilling gas hydrate in permafrost regions, the performance of cement slurry in low temperature is crucial to the control of wall protecting and leakage plugging in a borehole. In this research, the preparation, properties and hydration process of nano-composite cement (NC) in low temperature were comprehensively investigated by a combined method of theoretical analysis and experimental approach. In terms of the “synergistic hydration” effect induced by the compounding of ordinary Portland cement with sulphoaluminate cement, NC which aimed at stabilizing borehole in gas hydrate drilling in low temperature, it introduced sets of compositions of water reducing agent (JSS), early strength agent (LC), antifreeze agent (CC) and nano materials (SiO2) to examine its physical properties, such as rheology, fluidity, pumpability, setting time and compressive strength by lab tests. An integrated analysis of hydration exotherm, X-ray diffraction and scanning electron microscopy was used to pattern the low temperature hydration process of NC, and then it concluded a low temperature hydration process model to NC. The research results provide a scientific basis for promoting the application research of NC in low temperature, and provide a new solution for wall protecting and leakage plugging in the drilling of natural gas hydrate in permafrost regions.