Effect of field viscometer dial readings on the estimation of drilling fluid frictional pressure loss using Herschel–Bulkley model

Abstract

The main objective of this study is to investigate how uncertainties in dial readings would affect the frictional pressure loss estimation of the flow of drilling fluid in drill pipe. In this study, a new calculation procedure for determination of frictional pressure loss using the Herschel–Bulkley model is presented and verified with experimental data. A Monte Carlo simulation study is conducted to investigate the sensitivity of each dial reading on the estimation of frictional pressure drop for different circulation velocities. The results show that for the low yield fluids, 1o dial reading error introduces more than 6% error to the frictional pressure gradient prediction, especially at low flow velocity. While the errors in dial readings result in much smaller error in pressure gradient estimation for fluids with high yield stress, typically less than 5%. In addition, the readings at lower rotational speeds, i.e., 3 and 6 RPM, have a significant effect on the estimation of the frictional pressure loss, especially for low flow velocity and low yield stress fluids. More importantly, the uncertainty in dial readings has less effect on the frictional pressure drop estimation at moderately high flow velocity. This research also emphasizes the importance of rheological model parameter estimation using all available dial readings with the assistance of computational tools to better capture the rheological response of drilling fluids for better hydraulic calculation.