High Performance Water Reduced Cement Slurries Prepared With Low Cost Optimized Blend

Abstract

IntroductionA cement sluny is a suspension of solid particles in m1 aqueous solution. Sluny properties depend on many variables: the amount and nature of the solids, including cement the additives used, the amount and the type of water, the temperature and the pressure.For a given solid blend, the water-to-solid ratio detennines the slurry density. In the new approach to cementing described in tltis paper, differently to what is done traditionally, a blend has to be chosen as the first step in the system selection. Here the blend choice is a process which implies the identification of the materials providing the specific gravity required and the detem1ination of the optimal ratios between these different components.Blend quality is an essential parameter which plays a role, directly or indirectly, in all slurry properties. Once the blend has been optimized, slurry design is petfonned as usual, that is, thicketting time, rheology, fluid loss and stability are set at the proper levels, according to well conditions, by adding the proper amount of retarder, dispersant and fluid loss control agent, however this iteration process is much quicker and requires much lower additive concentration with optimized blends.

Long-Term High-Temperature Laboratory Cement Data Aid in the Selection of Optimized Cements

“…[1][2][3][4][5] Long-term testing for high temperature exposure on these cements has now been completed in order to determine their durability at 300 0 F. Previous literature shows positive results for physical properties for cements with HCS. The results reported were for relatively short-term testing.…”

New Cement System Replaces Mechanical Whipstock Plug

“…However, by replacing the Class G cement with a blend of particles with distinctly different and optimized particle-size distributions, 4 it is now possible to produce "pumpable" slurries with a PVF around 58-60% (Fig 1). The higher PVF means there is a more efficient use of the water in the slurry.…”

“…The compressive strength development of these slurries has also been shown to be more tolerant to contamination by the wellbore fluids. 4 Temperature also plays an important part in the rate of compressive strength development. Any attempts to increase the rate of strength development after the successful placement of the plug can correspond to direct savings in rig time.…”