Influence of mud cake solidification agents on thickening time of oil well cement and its solution

The research objectives were to investigate the influence of mud cake solidification agents (MCSAs) on thickening properties of oil well cement and its solution. The results of thickening time tests showed that MCSAs accelerated the oil well cement hydration remarkably by cutting down induction period. X-ray diffraction (XRD), gas chromatography and mass spectrometry (GC-MS), thermogravimetry and differential scanning calorimetry (TG-DSC) were applied in order to study the hydrates in the mixture of MCSAs and oil well cement slurry. The results showed that MCSAs promoted the hydration reaction of tricalcium silicate and dicalcium silicate, resulting rapid and massive calcium hydroxide formation at early hydration. Besides, the addition of MCSAs affects the transformation of calcium hydroxide to tobermorite under high temperature. Quantitative and qualitative analysis of silicate anions indicated that MCSAs promoted the formation of monomer. It can be inferred that the heterogeneous nucleation of calcium hydroxide and monomer on the surface of cement particles promoted by MCSAs is responsible for MCSAs on thickening properties of oil well cement. This paper also suggested that adding 1% calcium gluconate in MCSAs can solve this problem without weakening its performance.