Comprehensive Cuttings-Transport Model Optimizes Drilling Operations for Hole Cleaning

Abstract

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper IADC/SPE 199587, “Modeling Cuttings Transport and Annular Packoff Using Local Fluid Velocities With the Effects of Drillstring Rotation and Eccentricity,” by Oney Erge, SPE, and Eric van Oort, SPE, The University of Texas at Austin, prepared for the 2020 IADC/SPE International Drilling Conference and Exhibition, Galveston, Texas, 3-5 March. The paper has not been peer reviewed. This paper discusses a new, comprehensive cuttings-transport model designed to enable safe and improved hole-cleaning operations. Local velocity profiles are calculated for a given fluid and compared against the local critical velocity for cuttings transport. Then, the location and the magnitude of annulus blockage are numerically assessed. After an annulus becomes partially blocked with cuttings deposited in a cuttings bed, continuity and momentum equations are solved for the blocked annulus to estimate the new local velocities. The annulus is divided into small sections, and the pressure profile is calculated with the progression of time. The results from this study agree with large-scale flow-loop experiments and field observations, showing that axial flow alone is not enough for effective hole cleaning in high-deviation and horizontal wells. The results also provide a way to predict packoff events during which the string can become stuck, the equivalent circulating density can spike, and lost circulation can occur.