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EM PUBLICAÇÃO

EDIÇÕES

Boletim Técnico da Petrobras

Publicação:AGO /2011

Volume:54

Número:2

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Artigos
Expediente, Editorial e Sumário

A quarta edição do CFD OIL ocorreu na cidade do Rio de Janeiro nos dias 12 e 13 de junho de 2010, no Centro de Convenções do Windsor Florida Hotel, no Flamengo. O evento originou-se do 1º Workshop de CFD Aplicado à Indústria de Petróleo, realizado em março de 2003, também no Rio de Janeiro, com o objetivo de preencher uma lacuna existente no que se refere à divulgação da metodologia de Dinâmica dos Fluidos Computacional (CFD) aplicada à indústria de óleo e gás. O CFD OIL vem ganhando maior reconhecimento da comunidade científico-tecnológica a cada nova edição, e hoje já é considerado o mais importante evento de fluidodinâmica computacional aplicada à indústria de óleo e gás da América Latina. Organizado por Petróleo Brasileiro S.A. (Petrobras), Engineering Simulation and Scientific Software Ltda. (ESSS) e Laboratório de Simulação Numérica em Mecânica dos Fluidos e Transferência de Calor da Universidade Federal de Santa Catarina (Sinmec-EMC-UFSC), o CFD OIL tornou-se uma referência internacional na área de simulação computacional de escoamentos. Desde sua criação, o CFD OIL vem cumprindo com sucesso sua missão de reunir engenheiros, pesquisadores e desenvolvedores de códigos e metodologias numéricas na área de CFD com o objetivo de estimular a pesquisa e inovações que permitam maior eficiência no desenvolvimento de processos e equipamentos e ainda a previsão e solução de problemas (troubleshooting), otimização de processos existentes e melhoria de equipamentos de engenharia. Isso se dá por meio do compartilhamento de informações entre profissionais da indústria, de empresas de tecnologia e da academia, dedicados à busca de soluções para problemas que envolvem mecânica dos fluidos, transferência de calor e massa, e reações químicas em atividades de upstream, midstream e downstream.


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Multiphase flow solution in horizontal wells using a drift-flux model

This study presents a procedure to solve two-phase (gas and liquid) flows throughout an oil well with lateral mass inflow from the reservoir. The flow is considered isothermal and one-dimensional. Equations are discretized using a Finite Volume Method with a C++ (OOP) code implementation. This algorithm is intended to be used with a reservoir simulator to solve the coupled flow between the reservoir and well.


Autores: Arthur Besen Soprano, António Fábio Carvalho da Silva, Clovis R. Maliska

Palavras-chave

drift-flux, multiphase flow, horizontal wells

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CFD-DEM modeling of the gravel packing operation during horizontal well completions

Increasing oil exploration challenges require the development of new technologies to achieve higher efficiency in oil and gas extraction, for the lowest possible cost. Numerical simulations of processes facilitate solutions for several industry-faced problems, being able to achieve different virtual try-outs, which offer greater understanding to optimize the process in discussion. With the expressive computer capability development in the simulation field, computational fluid dynamics (CFD) has drawn most attention in recent years. This can computationally easily reproduce complex fluid flow phenomena such as turbulence, reactions, multiphase systems, etc. One of the gaps still taunting modern CFD codes is the incapacity to simulate, in detail, multiphase systems involving granular solids. These are common in many industrial processes, especially in the mining or oil and gas industry. The objective of this study is to develop a new methodology to numerically reproduce granular flows, sourcing a different tool to assist the calculation: the so called Discrete Element Method (DEM), used to perform particles transportation. The methodology adopted was to couple the CFD (Fluid Flow Calculation) and DEM (Particle Tracks Calculation). To assess and validate the proposed approach, the Gravel Packing process of horizontal wells was used as a simulation test. The gravel packing process is widely used by Petrobras to complete deepwater and ultra-deep water wells and a better comprehension could lead to more efficient and economical operations. The first obtained results proved that this approach is very promising, indicating it is possible to work numerically with the complex problem of high solid concentrations. The study’s main results show a validation of the alpha wave height obtained in numerical simulation based on experimental Petrobras data. The results supported the proposed approach suggesting the CFD-DEM coupling may, in the future, be used to aid the design operation of gravel packing in horizontal wells.


Autores: André Leibsohn Martins, João Vicente Martins de Magalhães, Jairo Z. Souza, João Américo Aguirre Oliveira Jr., Carlos Eduardo Fontes

Palavras-chave

Discrete Particle Simulation, Computational Fluid Dynamics, Multiphase Flow, Horizontal Gravel Packing

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Numerical simulation of a dummy well pumping module

A major challenge in oil production from offshore reservoirs is to keep the operation profitable during the field exploitation concession. Oil and gas production in deep and ultra deep water require the development of new production techniques, such as novel artificial elevation techniques. Currently, Petrobras is developing a new subsea pump module, equipped with na electrical submersible pump (ESP), known as MOBO applied to a multiphase mixture flow (oil, gas and/or water). The MOBO system architecture creates suitable flow conditions to assure pump operational continuity. This study simulated the pump flow behavior through computational fluid dynamics (CFD). Two MOBO geometries were built – with and without side holes in a shroud pipe that encases the ESP intake - to simulate an internal two-phase (water and air) flow. For numerical results validation, a comparison with previously acquired experimental results in the Petrobras Research Center (Cenpes), was performed and showed good agreement. The shroud pipe, strategically equipped with side holes, was able to expressively attenuate the phase discontinuities in the ESP intake region. This minimized gas discharge events and the associated lack of pump operational continuity. Numerical simulations with oil and gas, exhibiting similar characteristics to those found in the Campos Basin, also showed an absence of gas discharges within the tested conditions – by similarity laws corresponding to 3.034m3.d-1 of oil with 10% or 40% of free gas.


Autores: Luiz Carlos Tosta da Silva, Ricardo de Andrade Medronho

Palavras-chave

oil flow, pump module, submerged centrifugal pump, computational fluid dynamics

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Numerical simulation of a cyclone used as an inlet device of a gravitational separator

This study presents the numerical simulation of the flow inside a gravitational separator to evaluate the influence of each internal device in the separation efficiency. In this first stage, the cyclone – located at the vessel entrance, known as the primary separation – internal flow is investigated. The flow inside cyclones presents rather complex and challenging characteristics, such as: streamlines with high curvature, intense force fields, interaction between primary and secondary flows and anisotropic turbulence. A three-dimensional fluid dynamics study is resented of a gas-liquid two-phase flow in a cyclone. The two-phase flow was modeled using an Eulerian, isothermal approach. The main conclusion of these simulations is the phase separation inside the proposed initial design does not occur by centrifugal effect, as an internal rotating flow is not established, due to an ineffective inlet design. Based on the lack of this expected centrifugal field for a cyclone, it can be concluded that the device does not behave as such. As a result, the device efficiency is limited and possibly small droplets will be carried by the gas stream. Therefore, changes to the cyclone inlet geometry were proposed to better achieve the cyclone effect to increase the separation efficiency.


Autores: Carlos Alberto Capela Moraes, João Américo Aguirre Oliveira Junior, Lucilla Coelho de Almeida

Palavras-chave

cyclones, primary oil treatment, CFD

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CFD analysis for offshore systems: validation and applications

The Ocean Engineering group in the Petrobras Research Center develops and applies multidisciplinary simulation tools for several engineering problems mainly related to offshore systems. Recently, there have been many different cases where Computational Fluid Dynamics (CFD) has been successfully employed. This study presents a collection of cases where CFD simulations were validated against experimental data and directly used to facilitate solutions for practical problems. Case #01 calculated the maritime current loads on an FPSO and investigated the influence of appendices such as bilge keels and rudders on the near flow field. Similarly, Case #02 extends this procedure to the identification of wind loads. Case #03 calculates the hydrodynamic forces on a torpedo anchor during its installation. The simulation results coupled with a simplified dynamic model facilitates the directional stability of different torpedo models to be evaluated. A whole FPSO topside geometry is modeled in Case #04, which investigates the flow pattern near the FPSO Helideck. The simulation velocity and turbulence profiles were compared to wind tunnel measurements. These summarized cases show how CFD tools can be advantageously applied to solve many practical problems. All these simulations were performed using Ansys cfx®.


Autores: Daniel Fonseca de Carvalho e Silva, Paulo Roberto Pagot

Palavras-chave

CFD, offshore, aerodynamics, hydrodynamics, helideck, torpedo anchor

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2D simulation of leakage and damaged stability of oil carrier by MPS method

This study carried out numerical simulations of the coupled transient processes of the oil leakage or water flooding and analyzed the stability of a damaged crude oil carrier. The numerical approach based on Moving Particle Semi-Implicit (MPS) method was applied to assess the dynamics of a two dimensional reduced scaled model and the oil-water multiphase flow with free surface. The results were compared with the stability analysis software SSTab, which provided the final list angle, and showed good agreement. In addition to the oil leakage and water flooding dynamics, which provide important information such as time from the breakdown to final list, the study’s results also show the limits of the quasi-static approach.


Autores: Liang-Yee Cheng, Diogo Vieira Gomes, Kazuo Nishimoto

Palavras-chave

coupled analysis, oil leak, particle method, damaged stability, multiphase flow, MPS

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Numerical simulation of onshore separation processes – residence time optimization

Cylindrical tanks are commonly used in onshore facilities to process and treat oil and water streams. These tanks generate a gravitational separation and, when sedimentation velocity is reached, the residence time inside the tank is crucial to guarantee proper separation. The ideal geometry for a tank maximizes the effective residence time by providing the largest possible fluid path, along which sedimentation of the denser phase occurs. Large volume tanks can be used for this purpose. However, internal devices, which increase the effective residence time and decrease undesirable hydrodynamic effects, are a commonly used alternative, allowing a reduction in tank size. This study focuses on the application of computational fluid dynamics as a tool to analyze four geometries found in gravitational separation tanks to identify that which offers the highest residence time values.


Autores: Clarissa Bergman Fonte, João Américo Aguirre Oliveira Jr., Eduardo Stein Soares Dutra

Palavras-chave

numerical simulation, CFD, gravitational separation, tanks

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Applications of CFD in distillation, FCC and delayed coking technologies at Cenpes downstream basic engineering

The Oil and Gas Industry has several multiphase flow applications and the CFD technique is capable of bringing more accurate solutions for complex flow problems. Some cases require a deep understanding of the phenomena, for example, inter-phase heat and mass transfer and gas-particle interaction. Basic Engineering Process Teams (Coking, Distillation and FCC) have been using the CFD technique for more than seven years. The CFD cases played an important role in the improvement of these technologies. Some of them are discussed here: evaluation of inlet feed device, heat and mass transfer in empty sections, collector pans, cyclone dust hopper influence on the vortex core, coke drum effluent quench, inlet design and baffles in coke fractionators.


Autores: André Gonçalves Oliveira, Guilherme Pimentel da Silva, Karolline Ropelato, Washington Geraldelli

Palavras-chave

CFD, coking, quench, gas-solid, multiphase flow, separation, cyclone, fractionator

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Simulation of a three-phase three-dimensional reacting flow in an FCC industrial riser

This study used a three-dimensional and three-phase flow model to predict the dynamic behavior of a Fluid Catalytic Cracking (FCC) industrial reactor. It took into account heat transfer, feedstock vaporization and cracking reactions. The Eulerian/Eulerian-Lagrangian approach was used to simulate the dynamic three-phase flow inside the riser. The catalytic cracking reactions were predicted using the 4-lump model. A commercial CFD code (Fluent) was used to obtain the numerical data, and appropriate userdefined functions were implemented to model the heterogeneous kinetics and the catalyst deactivation. Results show nonuniform tendencies inside the reactor, emphasizing the importance of a sophisticated model in FCC process predictions.


Autores: Gabriela Cantarelli Lopes, Leonardo Machado da Rosa, Milton Mori, José Roberto Nunhez , Waldir Pedro Martignoni

Palavras-chave

numerical simulation, three-phase flow, FCC, vaporization, cracking reactions

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Computational simulation of natural convection in a square cavity containing a fluid with internal heat generation

Natural convection in cavities containing fluids with internal heat generation has been investigated in nuclear engineering in order to understand the heat transfer mechanisms in light water reactors (LWRs), after severe accidents with core melt- down. This paper reports computational simulation of natural convection in a square cavity containing a fluid with internal heat generation by using a commercial package of Computational Fluid Dynamics (CFD), Ansys CFX 12.0.The work aimed at analyzing the influence of fluid properties and the volumetric heat generation rate in the behavior of the flow regime and heat transfer, based on Prandtl (Pr) and Rayleigh (Ra) numbers. In a square cavity with isothermal vertical and adiabatic horizontal walls, steady laminar, transient laminar and turbulent regimes were identified, for Pr equal to 0.0321, 0.71 and 7.0. The identification of periodic and chaotic transient laminar flow was carried out by spectral analysis of instantaneous velocity and temperature. The critical Rayleigh number.at which transition from steady to transient laminar flow regime occurs was determined. Turbulent natural convection was studied by using Reynolds average Navier-Stokes (RANS) equations with SST model.


Autores: Camila Braga Vieira, Jian Su

Palavras-chave

natural convection, heat transfer, CFD, severe accident

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Computational Fluid Dynamics analysis for a combustion chamber in an industrial gas turbine

The accurate prediction of pollutant emissions from a gas turbine combustion chamber is a major concern when the equipment is subjected to long operational periods beyond its design point. Under such conditions, the flow field itself might also show big differences from the design point, leading, for instance, to undesirable hot spots or instabilities in the combustion process. A study of all possible operational conditions is economically unfeasible. Also a Direct Numerical Simulation (DNS) of industrial combustors is beyond the capacity of the foreseeable computational resources, therefore models must be used to analyze such issues. This study presents the results for an industrial gas turbine combustion chamber using Computational Fluid Dynamics (CFD). The model used contained an ad-hoc parameter for which a new formulation is proposed. The influence of this new formulation is examined both in terms of the flow field structure and the combustion stabilization mechanism.


Autores: Thiago Koichi Anzai, Carlo Eduardo Fontes, Karolline Ropelato, Luís Fernando Figueira da Silva, Luis Enrique Alva Huapaya

Palavras-chave

Combustion, Gas turbine, Computational Fluid Dynamics

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