Investigating Hole-Cleaning Fibers' Mechanism to Improve Carrying Cutting Capacity and Comparing Their Effectiveness with Common Polymeric Pills

Abstract

Abstract In drilling oil and gas wells, hole cleaning in deviated wells is more challenging in comparison with vertical wells due to boycott effect or eccentricity of drill pipe. Poor hole cleaning can result in problems such as borehole pack-off or excessive ECD. In these circumstances, increasing drill pipe rotation & flow rate and simultaneously using polymeric sweeps are common treatments to remove cuttings from the borehole, but these sweeps are incompetence in removing bulky high-density cuttings or metallic debris in milling operations. Also, in the condition of zero or low flow-rates, settling of particles in polymeric pills are high. In this paper, a specialized fibrous-type material (Fiber-1) for investigating hole cleaning effect of fibrous sweeps was used. The effectiveness of Fiber-1 in comparison with common polymeric pills (such as Xanthan gum and polyanionic cellulose) in different concentrations (1 to 3 lb/bbl) was investigated using rheological or cutting settlement tests. Mentioned tests were applied in synthetic well condition (2 hours rolling in 200°F). Hole cleaning fibers' main mechanism is forming a fiber network in the fluid that prevents cuttings to easily settle. The other mechanism that was observed in laboratory results, was an increment in rheological parameters such as Low Shear Viscosity (LSRV) and Yield Point (YP) that have a direct influence in cutting carrying capacity which this one is hardly mentioned in previous research works. For instance, results showed yield point was increased 25% when 2 lb/bbl Fiber-1 material was added to a common Xanthan gum pill. Also, readings in RPM 3 and RPM 6 (120°F) were increased by 17% and 18% respectively when 3 lb/bbl Fiber-1 material were added to common Xanthan gum pill. Also, the optimum concentration for having the maximum YP and LSRV (without getting any flocculation or settlement issues) was 2 lb/bbl. The invasion time for settling a metallic cutting in a pill containing 2 lb/bbl Fiber-1 was about ten times more than settling time in the common Xanthan gum pill. The main discussed issue in this paper is finding significant mechanisms of hole cleaning fibers and their merits in comparison with polymeric high-viscosity pills. Also, Fiber-1 as an environmentally friendly specialized fiber for reducing hole cleaning problems in challenging deviated holes were studied and was optimized for using in field applications.