The influence of ash from fluidized-bed combustion of lignite on rheological properties of cement slurries.
Krzysztof Skrzypaszek, Stanisław Stryczek, Rafał Wiśniowski
Vol. 31, no. 3 (2014), s. 403-411, 
Cementing jobs are a very important element of drilling technology considering the completion of a given field. The selection of an appropriate recipe for sealing slurry is a challenge for the cementing services and research units. Both fresh and set slurry should meet a number of technological requirements. Various chemical, physical and mechanical properties of the ground and rock mass media to a different degree influence the technological parameters of the injected fluid. The sealing slurries have to meet certain criteria if the high efficiency of works is to be provided. The first of them is the criterion of physicochemical congruence with the environment. The second condition stems from the criterion of pumping the slurry. It is realized by selecting an appropriate rheological model and rheological parameters of the sealing slurry. The third requirement is connected with the need of providing suitable strength and durability of hardened sealing slurries as a result of the physicochemical processes. The fourth condition should account for the economy and ecology factors. The selection of recipes for sealing slurries should not be accidental or an output of unfniished laboratory tests. The correct sealing and reinforcing of the rock mass are prerequisites of further engineering works performed in the wellbore. The results of laboratory experiments on the concentration of ash from the fluidized-bed combustion of lignites on rheological parameters of fresh sealing slurries based on drilling cement class G (HSR) Dyckerhoff (API Class G HSR - Black Label) for various water/cement ratios are presented in this paper.