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Development of a Three Layer Model for Simulating Transient Behavior Cutting Transport in Extended-reach Well

Akhshik, Siamak | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48004 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Behzad, Mehdi
  7. Abstract:
  8. A major concern in directional well drilling is the transport mechanism of cuttings by drilling fluid. This thesis describes the effect of angular velocity and postbuckled vibrations of drillstring on cuttings transport in a directional well drilling. The analysis proceeds in two stages. First, a finite element model is used to predict the dynamic behavior of postbuckled drillstring inside a directional well. Second, a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach to simulate the cuttings transport considering the dynamic collision process. In the combined computational fluid dynamics and discrete element method (CFD-DEM), the fluid phase is treated as a continuum phase described by the local averaged Navier-Stokes equations on a computational cell scale, while the particles are modeled as a discrete phase, solved by Newton’s laws of motion through the calculated flow field. The model takes into account the collisions of cutting-cutting, cutting-drill pipe and cutting-wall. The Herschel–Bulkley model is used to describe the rheological behavior of the non-Newtonian drilling fluid. The results revealed that the drill pipe rotation and oscillation decrease the cuttings volume concentrations. In addition, it is concluded that although the drill pipe rotation has a small effect on cutting transport, in combination with drill pipe oscillation, it helps to prevent a bed of cuttings being formed
  9. Keywords:
  10. Directional Wells ; Cutting Transport ; Post-Buckling Behavior ; Drilling ; Computational Fluid Dynamic-Discrete Element Method (CFD-DEM) ; Drill Pipe Rotation

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