Master of Science in Petroleum Engineering (MSPE)
Dispersion, deposition, and suspension of particulate materials in the carrier fluid play a significant role in the oil industry. Increasing the cuttings transport performance in deviated wells is difficult due to the rolling/sliding transport, and cuttings settling on the low side of the annulus. Insufficient cuttings transport may lead to some crucial problems such as pipe sticking, increasing in torque and drag, material damage and bed cementing quality. Increasing flow rates and improving mud properties may not be applicable for a proper hole cleaning because of the hydraulic and mechanical limitations. In such cases, additional pressure may be generated, and this causes formation fractures and drilling fluid losses. Under these circumstances, the other major contribution to cuttings transport is provided by drill-pipe rotation. In this study, the effect of drill-pipe rotation on cuttings transport behavior is investigated for eccentric horizontal wells. Whirling motion of drill-pipe is also analyzed. During drilling, drill-pipe is subjected to axial, lateral and torsional loads due to the dynamic vibrations. These loads cause that drill-pipe to lose its stability and generate snaking and/or whirling type of motion. Dynamic behavior of drill-pipe plays a significant role on cuttings transport and stationary bed removal. Turbulence modeling becomes very complicated when cuttings transport includes deposition and sliding effects. Advanced turbulence models are required to get accurate flow predictions while optimizing computational resources requirements. Unsteady SST k-ω turbulence model is applied due to its practicability and reliability in predicting cuttings transport behavior. Discrete phase is modeled with discrete element method (DEM) by including particle-particle and particle-fluid interactions with a commercial ANSYS FLUENTTM 15.0 CFD package using LSU high performance computing (HPC) resources. It is concluded that cuttings concentration significantly decreases with increasing flow rate. Drill-pipe rotation around its own axis causes cuttings swaying and distribute asymmetrically along the circumferential direction. Orbital motion of the drill-pipe contributes more to cuttings transport performance. Low whirling rotary leads to increase in annular pressure losses in low flow rates. In the turbulent flow regime, however, annular pressure losses increase with increasing whirling speed.
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Demiralp, Yasin, "Effects Of Drill-pipe Whirling Motion On Cuttings Transport Performance For Horizontal Drilling" (2014). LSU Master's Theses. 2238.