Prediction of Laminar and Turbulent Friction Pressures of Cement Slurries in Pipes and Centered Annuli

Abstract

Abstract Friction pressures of different cement slurry formulations with properly characterized rheologyhave been measured in a wide variety of flow situations, including laminar (20 to 1000 s-1) and turbulent (2000 <Re< 10000) flow regimes. Tests were performed in pipe and concentric an- nular geometries, using a pilot-scale rig. In laminar flow, it was established in a previous publication that pipe flow friction losses of cement slurries can be reliably predicted from rotational viscometer measurements made inthe shear rate range of the actual pipe flow. In this paper it is shown that valuable predictionscan also be obtained for concentric annuli, at least when the radius ratio (inner/outer) is greater than 0.3, if the geometry is approximated by a rectangular slot. Pipe flow experimental data obtained in the turbulent flow regime are compared to several existing models. A modified Dodge and Metzner approach to the problem was found to give the best agreement with the measurements. For concentric annuli, a similar procedure is shown to be acceptable when used with the rectangular slot approximation. Reasonable agreement is found between model predictions and experimental results. For both flow regimes, the proposed method is no more complicated and is proved, for most field situations, to be much more accurate than the API procedure in predicting pressure drops.