The Effect of Drillpipe Rotation on Annular Frictional Pressure Loss

Abstract

Accurate predictions of annular frictional pressure losses (AFPL) are important for optimal hydraulic program design of both vertical and horizontal wells. In this study, the effects of drillpipe rotation on AFPL for laminar, helical flow of power law fluids are investigated through theoretical, study, flow models were developed for concentric and eccentric pipe configurations assuming that pipe rotates about its axis. A hybrid-analytical solution is developed for calculating AFPL in eccentric pipe configuration. Computer simulations indicate that the shear-thinning effect induced by pipe rotation results in reduction of AFPL in both concentric and eccentric pipe configurations. The pressure reduction is most significant for concentric pipe configurations. For conventional rotary drilling geometry and pipe rotary speeds, the reduction in AFPL is small. A number of laboratory experiments conducted on the full-scale TUDRP flow loop are generally in good agreement with the results of modeling. Available fileld data, however, consistently show an increase in AFPL. This behavior is explained by pipe lateral movement (swirling), which causes turbulence and eventually an increase in AFPL.

Frictional Pressure Loss Estimation of Non-Newtonian Fluids in Realistic Annulus With Pipe Rotation

“…Nouri and Whitelaw (5) stated that the rotation had similar effects on the Newtonian and non-Newtonian fluids, with a more uniform axial flow across the annulus and the maximum tangential velocities in the narrowest gap in both cases. Wei et al (6) carried out theoretical, experimental and field data studies of the effects of drillpipe rotation on annular frictional pressure loss for laminar, helical flow of power-law fluids. With drillpipe dynamic influence, the annular pressure loss is the combined result of shear-thinning effect and drillpipe dynamic effect.…”

On the orbital motion of a rotating inner cylinder in annular flow

“…This type of annular flow has been widely investigated for both Newtonian and power-law fluids when the inner cylinder is rotating at different angular velocities and eccentricities. Recent work in this field had been reported in References [1][2][3][4][5][6]. In all these studies the axis of the rotating inner cylinder is stationary with respect to the outer cylinder.…”

“…x-and y-component of the resultant force on the inner cylinder per unit length caused by shear stress, F Xs / ( R I ) 2 and…”

Numerical Modeling of Helical Flow of Pseudoplastic Fluids

“…This results in a biharmonic equation rendering the solution process to be inherently dif¢cult. A simplistic procedure was undertaken by Wei et al [10] involving power-law £uids in an eccentric annulus. They formulated a hybrid-analytical solution based on the concentric annulus solution for the eccentric case using a constant inner pipe radius and a variable radius for the outer pipe to account for the eccentricity.…”