Research on the hydration mechanism of oil base fine cement slurry

The hydration mechanism of selective water shutoff material - oilbase fine cement slurry was studied by use of these methods, such as TG, DSC, XRD, SEM, MIP and so on. The chemical combined water content in bond cement was measured by burning weight-loss method; Ca (OH)₂ content by glycerine test methods; and the hydration level of oilbase fine cement slurry was analyzed. The research results indicated that the hydration rate of the slurry was fast in early stage and Ca(OH)₂ was rapidly formed and accompanied with a large number of hydration products as CSH, etc., the compressive strength of hardened oilbase bond cement was mainly affected by water-to-cement ratio (W/C); its highest compressive strength might be reached when W/C=0.26; and its good hardening could be realized within a wide W/C range. There fore this slurry is an excel lent selective water shutoff material. The porosity in hardened oilbase bond cement is larger than that in waterbase bond cement which is the main cause of the former's lower compressive strength.