EXPERIMENTAL AND MODELING STUDIES ON HOLE CLEANING OF HORIZONTAL WELLS WITH FIBROUS FLUIDS

Abstract

The drilling of horizontal and highly deviated wells has become essential for maximizing reservoir contact and improving hydrocarbon recovery. However, effective hole cleaning remains one of the most critical challenges due to limited hydrodynamic assistance, leading to cuttings bed formation and associated problems such as increased torque, drag, stuck pipe, and non-productive time. Conventional drilling fluids often fail to maintain adequate solids transport under these conditions. Recent studies suggest that fibrous fluids can enhance suspension and transport characteristics, but their mechanisms and modeling remain poorly understood. This research evaluates the effectiveness of fibrous fluids in improving hole cleaning in horizontal wells using experimental and modeling approaches. A customized horizontal flow loop was developed to replicate wellbore conditions. Polymer-based drilling fluids were tested by measuring equilibrium bed height and pressure loss under varying flow rates, pipe rotation speeds, and fiber concentrations. Results demonstrated that the addition of long synthetic fibers significantly enhanced cuttings transport efficiency, particularly in low-viscosity fluids at high flow rates. Short fibers, however, provided minimal benefits. Pipe rotation exhibited a strong synergistic effect with fibrous fluids by promoting disturbance and resuspension of settled cuttings beds. The resuspension improved transport efficiency, especially under laminar flow regimes where turbulence is absent.