Abstract
The drilling community generally believes that pipe rotation helps hole cleaning during both drilling and cementing. However, there has been a lack of reliable calculations to describe the effect and application in engineering and design and deployment. This paper discusses the effect of pipe rotation on velocity profile and pressure drop in concentric and eccentric annulus during the axial flow of non-Newtonian fluid. The calculations are applied to the design of hole cleaning during drilling and cementing.
In the absence of reliable calculations one can only guess the impact of pipe rotation on hole cleaning. This work gives an engineer the tool to design for improved hole cleaning and hence save time and money during well construction and production.
Pipe rotation is all the more important in an eccentric annulus to remove the drill cuttings and the gelled drilling fluid from the narrow annulus. This is because in an eccentric annulus, in the absence of pipe rotation, the fluid flows preferentially through the wider annulus. The pipe rotation speed (i.e., the RPM) required to move the gelled drilling fluid and the drill cuttings in various annulus configurations and eccentricities are presented. The results discussed in this paper can be applied for effective hole cleaning during drilling and cementing, which should save nonproductive time (NPT) during drilling and cementing and also reduce remedial and intervention costs during well production.
