Experimental study of cuttings transport with non-newtonian fluid in aninclined well using visualization and ert techniques

Hole cleaning is a concern in directional or horizontal well drilling operation where drill cuttings tend tosettle in the lower annulus section. A lab-scale experiments were performed with different non-Newtonianfluids in a 6.16-meter-long, 4.5-inch × 2.5-inch transparent annulus test section to investigate cuttingstransport behaviour. This experimental study focused on understanding the cuttings transport mechanism inthe annulus section with high-speed imaging technology. The movement of cuttings in the inclined annularsection was captured with a high-speed camera at 2000 frames per second. Also, cuttings bed movementpatterns at different fluid velocity and inner pipe rotation were captured with a DSLR video camera. Theelectrical resistance tomography (ERT) system was used to quantify the cuttings volume fraction in theannulus. Different solid bed height and cuttings movement were observed based on fluid rheology, fluidvelocity and inner pipe rotation. The mechanistic three layers cuttings transport model was visualized withthe experimental procedure. This study showed that solid bed height is significantly reduced with an increasein the inner pipe rotation. This study also identified that cutting bed thickness largely depends on fluidrheology and wellbore inclination. The image from the high-speed camera identified a downward trend ofsome rolling particles in the annulus due to gravitational force at a low mud velocity. Visual observationfrom high-speed camera identified a helical motion of solid particles when drill pipe is in contact withsolid particles and rotating at higher RPM. Different cuttings movement patterns such as: Rolling, sliding,suspension, helical movement, downward movement were identified from the visualization of a high-speedcamera.