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EM PUBLICAÇÃO

EDIÇÕES

Boletim Técnico da Petrobras

Publicação:DEZ /2012

Volume:55

Número:3

Artigos mais procurados

Artigos
Compositional thermo-physical model and rheological characterization of heavy oils coupled with ANSYS CFX

A non-Newtonian viscous model is used to correlate experimental data of shear-thinning rheological behavior of dead crude oils ranging from 13 to 21º API. In the proposed model (cross model) the low and high shear rate viscosities are functions of temperature and the shear-thinning region is represented with a power law. The variation of viscosity with pressure is taken into account through the oil density, and consequently, a compositional thermodynamic model is developed to calculate the volumetric properties. The rheological and thermo-physical models are then implemented in ANSYS CFX as Fortran routines to analyze the pipeline system at the discharge of a storage tank for a 21º API oil.


Autores: Adrián González-Villanueva, René Moisés Hernández-González, Humberto Hinojosa-Gómez

Palavras-chave

non-Newtonian behavior, Peng-Robinson equation of state, cross model

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Study and application of transient characteristics of fluid phenomena for downhole (oil and gas) pulsating devices using FLUENT ANSYS

A fluctuating fluid flow inthe wellbore can provide intangible benefits in well stimulation applications.  A pulsating device (PD) is a device with no moving parts that generates an oscillating jet of fluid at predesigned frequencies. Figure 1 shows the conceptual basis of a PD is the Coanda effect (Webbet al., 2006), which is the tendency of a fluid jet to be attracted to a nearby surface. Figure 2 illustrates the PD producing emissions of alternating bursts of fluid that create pulsating pressure waves within the wellbore and perforations (if present). As each burst is ejected, it forms a compressive wave within the wellbore fluid. As the wave passes through the formation and reflects back, it incurs a tensile loading on the skin damage. Continued cycling of these pressure waves causes the skin damage to reach its fatigue failure point. Scale is fatigued to failure then removed as a result of the fluidic oscillation, helping restore and enhance the permeability of the perforations in the near wellbore (NWB) area.  Another benefit for the PD is in optimizing the placement of treatment fluids into the NWB area, yielding better contact coverage and thus better treatment results.


Autores: Bharat Pawar, Koustubh Kumbhar, Timothy Hunter, Harit Naik

Palavras-chave

Coanda effect, perforations, wellbore, formation

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A comparative study of turbulence models for the computation of the detached flow over bluff bodies

This paper presents a comparison of Large Eddy Simulation - LES and Scale Adaptive Simulation - SAS versus the k-ω SST model, based on the URANS approach, for the computation of the detached flow around bluff bodies, which is a common case in flow computation over offshore structures.The flow around a square section obstacle, mounted on the floor of a wind tunnel, was used as a test problem.The results were compared with experimental PIV data provided by CFD Society of Canada Challenge 2012, for this problem (CFDSC, 2012). As was expected, the LES simulation resulted in the resolution of much finer turbulence structures than the SAS and URANS simulations, but it was perceived that all three techniques provided average quantities in good agreement with the experiments. Since the timestep and mesh requirements of the LES approach are more stringent, results indicate that for industrial applications the SAS technique is a good compromise between accuracy and computational costs.


Autores: Clovis Raimundo Maliska, Emilio Paladino, Bruno Alexandre Contessi, Régis Silvestre da Costa Ataides, Vinicius Girardi Silva

Palavras-chave

offshore structures, CFD, detached flow, turbulence modeling

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Numerical and experimental study of dynamic flow behavior in a laboratory-scale bubble column operating under homogeneous and heterogeneous regimes

Experimental and numerical techniques were applied to a bubble column where the gas-liquid flow behavior was evaluated. The physical experiments were performed in an Experimental Unit of Bubble Column (EU-BC), changing the superficial velocity of the gas phase (U) within the range of 0.05 and 0.10m s-1. The global gas holdup and average axial velocity of the liquid phase were measured using pressure probes and particle image velocimetry (PIV), respectively. These data were used to validate a numerical model of the bubble column. The experimental results show classical hydrodynamic behavior for the gas holdup and liquid velocity profile of the equipment. The numerical study was developed considering that the bubble column comprises three phases: liquid, "small" bubbles and "large" bubbles, and the Eulerian description was applied to each of these phases. The bubble phases interact with the liquid phase using drag and lift (only to “small”) forces, while "small" and "large" bubbles do not interact with one another. The drag coefficients applied for small and large bubbles were those used by Krishna et al. (1999). The simulation results showed good agreement with the experimental study for global holdup and mean axial liquid velocity.


Autores: Renato Soccol, Ana Carolina Galliani Piscke, Dirceu Noriler, Henry França Meier

Palavras-chave

bubble column, two-phase flow, experimental study, CFD, mathematical modeling

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CAE Simulation applied to oil and gas products and processes

Simulation is a key technique in Petroleum Engineering, since it can reduce the time, money and resources utilized. Most simulations must apply fast computing to emulate equipment use or, broadly speaking, a complete process. The developed or applied simulation software is able to integrate not only the projected system (piece of equipment or process) but also the non-project scenario such as out-of-specification application and troubleshooting. Engineering simulation projects in the Oil and Gas industry from upstream to downstream have been developed by ESSS, a Brazilian spin-off company dedicated to research problems and deploy solutions, bringing to its customers the best-in-class of engineering associated with a reduction of time, money and resources utilized. Sub-areas of the Oil and Gas business have their own technical approach and investment, thus very specific analysis that allows the use of simulation software: Well and Drilling Engineering, Multiphase Flow in Porous Media, Hydraulic Fracturing, Acid Stimulation, Water Injection, Welding, Downstream and Upstream Equipment for Combined Gas-Liquid-Solid Separation and Equipment with Fluid Structure Interaction. After twenty years of project development, ESSS has accomplished a reasonable task in providing more knowledge to this industry.


Autores: Leonardo Paes Rangel

Palavras-chave

petroleum engineering, software, simulations, CAE, CFD, FEA, EDA

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Modified porosity distributed resistance combined to Flamelet combustion model for numerical explosion modeling

The porosity concept has been previously applied in explosion simulations. However, it has also been considered in numerical solvers which rely on structured mesh. Several issues appear when using structured mesh in curved shaped
geometries (fairly common in chemical process areas). The current work is based on a novel modelling of the geometry relying on unstructured mesh and porosity distributed resistance approach. The modeling is implemented in a fully 3D Navier-Stokes compressible formulation. Combustion is treated using a laminar flamelet approach based on the Bray,
Moss and Libby (BML) formulation. Results agree satisfactorily with experiments and the modeling is found to be robust.


Autores: Savio Souza Venancio Vianna

Palavras-chave

turbulent combustion, explosion, unstructured mesh, porosity

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Development and validation of a morphology detection algorithm (AIAD) for horizontal two-phase flows

In order to improve the understanding of counter-current two-phase flows and to validate new physical models, CFD simulations of 1/3rd scale model of the hot leg of a German Konvoi Pressurized Water Reactor (PWR) with rectangular cross section was performed. Selected counter-current flow limitation (CCFL) experiments at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) were calculated with ANSYS CFX 14 using the multi-fluid Euler-Euler modeling approach. The transient calculations were carried out using a gas/liquid inhomogeneous multiphase flow model coupled with an SST turbulence model for each phase. In the simulation, the surface drag was approached by a new correlation inside the Algebraic Interfacial Area Density (AIAD) model.


Autores: Thomas Hoehne

Palavras-chave

computational fluid dynamics (CFD), counter-current flow limitation (CCFL), pressurized water reactor (PWR), hot leg, algebraic interfacial area density (AIAD)

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Vortex-induced vibration simulation in a freeoscillating cylinder

The flow around a circular cylinder was simulated using both laminar and turbulent modeling, depending on Reynolds number (laminar for the Re 200 case and turbulent for Re 10.000 case). The preliminary cases were run with a Reynolds number of 200, for the purpose of testing the methodology, the moving mesh methods and the parameters settings. For those cases, a laminar formulation was used and a two-dimensional mesh was built, in order to save time and computational resources. In the Re 10,000 cases, the LES turbulence model was used and a tri-dimensional mesh was applied. The cylinder is free to oscillate in the transverse direction and the Rigid Body motion equation is solved with external elastic and damping forces. Simulations were carried out for a small mass-damping parameter m*z=0.013, where m*=3.3 and z=0.0026.


Autores: Vinicius Girardi Silva

Palavras-chave

CFD, LES, Smagorinsky, vortex-induced vibration, VIV, bluff body, cylinder

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Interviews

In an oil field, throughout its productive life, it is common to produce oil, gas and water simultaneously together with other contaminants such as sand. This makes it necessary to use equipment to carry out the first processing of the mixture in a controlled manner. The objective is to separate the oil, gas and water so as to ensure compliance with the standards in force for subsequent transfer to terminals or refineries, or conditioned for reuse in the primary processing plant itself or for disposal.


Autores: Carlos Alberto Capela Moraes, Daniel Fonseca de Carvalho e Silva, Luís Fernando Figueira da Silva

Palavras-chave

interview

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