Tertiary gelation of oilwell cement

The aim of this research was the investigation of the origin of the oilwell cement slurry gelation problem which can appear during well-cementing oper ations. In this study, the relations between the development of consistency of cement slurry, the hydration process and surface growth in the paste we re studied for several commercial oilwell cements. The effect of gypsum con tent on the consistency of cement slurry was evaluated. In order to relate the hydration process and the consistency development, the hydration of cem ents was followed by thermogravimetric analysis (TGA), X-ray diffraction an d by proton NMR spectroscopy. A comparison between the results obtained and some published data is presented. (C) 2000 Elsevier Science Ltd. All right s reserved.