Studying the physico-chemical properties of commercially available oil-well cement additives using calorimetry

Cement additives are typically used to modify the behavior of oil-well cement and to control its fluidity under well conditions. In this study, the retardation effect on cement hydration is investigated for a commercially available lignosulfonate and an NSF condensate at seven different concentrations. Additive solutions at 0.1% and 0.2% each by weight of cement (bwoc) with a ratio of (1:1) are also studied. The retardation of cement hydration process is monitored via isothermal calorimetry. Rheological studies are conducted to study the plasticizing effect induced by these additives. The mechanisms accompanying this process are better understood by studying the morphology of cement/additives systems using environmental scanning electron microscopy. The results show clearly that NSF has a retardation effect on cement hydration reflected on crystal growth. In addition, rheological measurements show that sodium lignosulfonate is more effective than NSF. The rheological effect alters with different cement/additive systems. This article provides recommendations for applying the most effective additive dosages in drilling and well-completion operations as well as enhancing the well-cementing quality.