Lateral forces on spheres in turbulent uniform shear flow

The increasing global energy demand has pushed the oil industry towards developing more innovative and advanced methods of enhancing oil recovery even under unfavourable technical and environmental conditions. The severity of many operational problems affecting the drilling and production of oil and gas wells is worsened by inaccessibility; hence, remedial efforts must be implemented from afar. One of these problems is ensuring efficient removal of formation rock cuttings with a suitable fluid, whose rheology is often complicated. Furthermore, pressure losses along the annular geometry involved, and decreased Rates of Penetration (ROP) due to accumulated drill cuttings downhole, constitute significant portions of the total energy to be supplied. Thus, the application of sophisticated modelling techniques with credible elucidation of the phase distributions (solids, liquids and gas) and prevalent flow regimes becomes essential, if adequate and economic design of a drilling program is desired. The advent of Computational Fluid Dynamics (CFD) and the growth in the available computational power to support it have provided an unprecedented opportunity to simulate and understand complex real flows, especially when experimental methods become extremely demanding. The present study employs the tool of Computational Fluid Dynamics to simulate a two-phase solid-liquid flow in an annulus based on the analysis of cuttings concentration, pressure drop profiles, axial fluid, and solid velocities as a function of several drilling parameters: drill pipe eccentricity, inclination, drill pipe rotation, ROP and fluid rheology. Special emphasis is however, placed on the impact of changing hole eccentricity on cuttings transport efficiency. The suitability of the Eulerian-Eulerian (EE) multiphase tracking scheme in modelling systems of high volume fractions is fully utilised in this work. A non-Newtonian (power law) fluid model with well-described flow parameters is implemented, considering a uniform cuttings size distribution (3 mm). A commercial CFD software (ANSYS FLUENT TM 17.1) has been used; the descriptive and predictive potential of the CFD software has been confirmed on account of the reasonable agreement with previously published experimental data (a relative error of less than 11% is achieved), as illustrated by the corresponding sensitivity plots. This multi-parametric CFD analysis study of multiphase cutting transport during drilling applications has confirmed that fluid velocity, hole inclination and annular eccentricity are the most influential factors governing the cuttings transport efficiency.2

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“…Its applicability to spherical and slightly distorted particles make it more robust compared to the Moraga (1999) …”

Section: Particle Lift Modelmentioning

confidence: 99%

A multiparametric CFD analysis of multiphase annular flows for oil and gas drilling applications

Epelle

Gerogiorgis

2017

Computers & Chemical Engineering

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“…The quantitative description of the saturation processes of M and V requires incorporation of all relevant forces acting on the sediment particles in transport, namely drag, gravity, buoyancy, collision forces between particles in transport ("mid-fluid collisions") and friction due to collisions between particles and the bed. Indeed, Moraga et al [27] found experimentally that lift forces due to shear flow acting on a particle surrounded by fluid -which have often been assumed to be significant during transport (e.g. [2]) -are approximately an order of magnitude smaller than the drag force and can be, thus, neglected in our calculations.…”

Section: Flux Saturation In Sediment Transportmentioning

confidence: 99%

Analytical model for flux saturation in sediment transport

et al. 2014

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The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment and for a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out-of-equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and can thus be applied under different physical conditions.

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“…In the past, several constitutive models of the forces acting on a bubble have been derived from the experimental investigations on the motion of single (isolated) bubbles (Ishii and Zuber, 1979;Zun, 1980;Drew and Lahey, 1987;Auton, 1987;Antal et al, 1991;Tomiyama, 1998;Hosokawa et al, 2002) as well as from numerical studies (Lopez de Bertodano et al, 1994;Kataoka and Serizawa, 1997;Moraga et al, 1999;Okawa et al, 2002 among others). These models seem to be appropriate for a broad range of flow parameters.…”

Section: Introductionmentioning

confidence: 99%