Research On The System Of Low Temperature And Early Strength Cement

Deepwater cementing is confronting with many challenges, especially the operation under low temperature and low formation fracturing pressure. Hence, how to improve the comprehensive properties of cement slurry under deepwater low-temperature condition, and accelerate the evolution of the compressive strength of set cement, are of great importance for deepwater cementing.Aiming at the easy lost circulation in deepwater formation cementing and the slow development of early strength of set cement under low temperature, extensive literature review, theoretical analysis and derivation were conducted. Based on the fractal geometry theory, a fractal successive grading model for Particle group was established. The Particle size distributions for grading raw materials were analyzed by the Particle size laser test machine, and the fractal grading model was compared with the Andreasen equation to obtain the fractal dimension range for the closest Packing effect. In accordance with the requirements in deepwater cementing, a ternary lightweight cement slurry system with slurry density of 1.32g/cm3 was optimized and designed. Through considerable optimization tests, the optimal concentration of cement accelerator was obtained. Simplified combination tests were carried out to get the accelerator formulation, which can significantly promote the strength development and enhance the compressive strength of set cement under low temperature. Then synthetic experiments were conducted to produce a new solid accelerator. On the basis of the above-mentioned tests, the types and concentrations of other additives were experimentally screened, and an early-strength lightweight cement slurry system was ultimately obtained with favorable stability, low water loss, good rheological property for cement slurry and high early strength for set cement.