ABSTRACT
Spacer fluids were initially used in the well construction process to separate drilling mud and cement slurry, which are considered as two chemically incompatible fluids. Beside separating these two fluids, spacers should completely remove the drilling mud remaining from the casing pipe and formation rock surfaces to guarantee a high quality bond between the cement and adjacent surfaces. There are several practical methods in the oil and gas industry to evaluate the mud removal efficiency of the spacers. However, these methods are not capable of assessing the spacer efficiency in removing mud cake, which usually forms on the formation rock surface. Presence of even a thin mud layer on the rock surface can significantly decrease cement bond quality. In this work, a method is proposed to evaluate the mud cake removal efficiency of a high density spacer fluid.
