Advanced Hole Cleaning in Horizontal Wells: Experimental Investigation Supported by a Downhole Clamp-On Tool

Abstract

Up to 80% of stuck pipe events are hole cleaning related in the case of high-angle wells. Therefore, significant attention should be given to understanding hole cleaning as it is crucial to restricting stuck pipe-related non-productive time (NPT). In order to optimize hole cleaning efficiency, the fundamental objective of the proposed paper is to experimentally investigate cuttings transport supported by a downhole clamp-on tool. This work approaches existing challenges by designing and building a custom flow loop that recreates the drilling environment of horizontal wells. The study provides additional steps and new ideas in developing a reliable experimental setup for a proper hole cleaning investigation. Accordingly, the process includes comprehensive dimensional analysis, detailed design, and building a desired experimental flow loop setup. A unique mechanical design allows pipe rotation while achieving a closed-loop system. A clamp-on tool assists in agitating the cuttings to reduce accumulation at the bottom of the borehole. Experimental performance with various cuttings compares scenarios with and without pipe rotation. Among the key factors influencing cuttings transport in horizontal wells are drill pipe rotation (RPM), flow rate (Q), mud rheology, cuttings size, flow regime, and penetration rate (ROP). This research focuses on the mechanical removal of solid cuttings. Experimental work emphasizes cuttings' behavior showing different patterns for their movement in deviated wells by utilizing image processing. Drillstring rotation proves to be a crucial factor for efficient hole cleaning. The specific shape and dimensions of the clamp- on tool affect the efficiency of the hole cleaning process and impact the distance covered by the agitated cuttings downstream of the tool. The concept of the tool depends on blades that agitate cuttings as it rotates. Optimum tool design considers the physical properties of the fluid and the cuttings. The results show that as the tool agitates cuttings and moves them into the higher velocity region, the cuttings advance with the flow, which improves cuttings transport and reduces bedding formation. Assuming low flow rates, tool application increased average particle velocity within the tool more than four times (372%) and twice after the tool. In addition, differential pressure (Δp) shows a significant decrease while the tool operates, indicating improvement in hole cleaning. Lab-scaled flow loop development aims to simulate drilling conditions with drillpipe rotation and different downhole clamp-on tool geometries. The results show different flow patterns from experimental observations of liquid-particles flow in the horizontal wellbore, assisted by the proposed downhole clamp- on tool. The innovative tool design is a promising step in reducing hole cleaning issues with mechanical- assisted tools.