Performance of polyethylene and polypropylene beads towards drill cuttings transportation in horizontal wellbore

摘要

Drilled cuttings removal is critical in drilling operations, especially in horizontal wells. These cuttings are postulated to be among the possible causes of many costly complications, such as mechanical pipe sticking, bore hole instability, drag and torque. This study proposes a new approach that uses polymer beads as a mud additive to improve cutting transportation. In this study, the effect of the concentration of polyethylene (PE) and polypropylene (PP) polymer beads on cuttings transport efficiency (CTE) in water-based mud in a horizontal wellbore was investigated. Experiments were conducted in a lab-scale flow loop equipped with a 13-ft (3.96 m) test section consisting of a concentric annulus acrylic outer casing (2 in. ID) and a static inner PVC drill string (0.79 in. OD). A total of 150 tests were conducted using 10 ppg water based mud (WBM) with 1%-5% by vol. Concentrations of polymer beads (PE and PP) were added at a range of 8-9.5 cp. Six different sizes of drilled cuttings ranging from 0.5 to 4.0mm were used as samples to determine the CTE at a constant 0.69 m/s average annular fluid velocity. The results revealed that CTE increased with the increase of polymer bead concentrations and that PP is better compared to PE overall due to its low density. The highest CTE was recorded at a 5% concentration of water-based mud polypropylene (WBMPP), which is approximately 96% for cutting sizes of 0.50mm-0.99 mm.