Multiphase flows commonly occur in the production and transportation of oil, natural gas and water. In this type of flow, the phases can flow in different spatial configurations disposed inside the pipe, so called multiphase flow patterns. The identification of flow patterns and the determination of the pressure drop along the pipe lines for different volumetric flows are important parameters for management and control of production. In this sense, this work proposes to numerically investigate the non-isothermal multiphase flow of a stream of ultraviscous heavy oils containing water and natural gas in submerged risers (catenary) via numerical simulation (ANSYS CFX 11.0). Results of the pressure, volumetric fractions and temperature distributions are presented and analyzed. Numerical results show that the heat transfer was more pronounced when using the largest volume fraction of gas phases.

The onshore and offshore production of oil and natural gas is characterized by the multiphase flow in ducts and pipes, which are interconnected by various equipments such as wellhead, pumps, compressors, processing platforms, among others. The transport of oil and oil products is essential to the viability of the sector, but is susceptible to failures, that can cause great environmental damage. Considering this necessity of the transportation sector of oil and derivatives, leakage in pipelines with curved connections, are the object of study for various researchers. In this sense, this work contributes to the study of three-phase flow (oil-water-gas) in a curved pipe (90°) using Computational Fluid Dynamics. The physical domain is constituted by two tubes of 4 meters trenched by a 90° curve, with the poring whole in the curvated accessory. The mathematical model is based on a particle model, where the oil is considered as a continuous phase and the water and gas as a particulate phase. The SST (Shear Stress Transport) turbulence model was adopted. All simulations were carried out using the Ansys CFX® 12.1 commercial code. Results of the pressure, velocity and volumetric fraction of the phases are presented and discussed.

The oil industry has sought to minimize the environmental impact from mining activities and oil transportation. The oil transportation by pipeline is subject to failures and leaks that cause financial losses and environmental damage, often irreparable. In this sense, the aim of this study is to evaluate the influence of the leak diameter in the behavior of the two-phase flow (oil and water) in a pipe. A transient and incompressible multiphase flow mathematical model based on the particle model was used here. Oil is the dispersed phase while water is the continuous phase. To model the turbulence effect it was used the standard k-ε model. All simulations were carried out using the Ansys CFX® commercial code. Results of the pressure, velocity and volumetric fraction of the phases are presented and discussed. The results confirm the difficulty to detect leakage with small diameters.

RESUMO -O transporte de petróleo e seus derivados é realizado, na maioria das situações, por meio de dutos interligando os poços de produção em terra, plataformas, refinarias, terminais marítimos e os centros de estocagem. Grandes investimentos têm sido realizados no desenvolvimento de tecnologias para o transporte de fluidos em dutos, visando o aumento do nível de segurança e eficiência de operação Apesar de ser considerado o meio mais econômico de transporte quando comparado às vias ferroviária, marítima e rodoviária, a operação com dutos está sujeita a falhas, ocasionadas pela ação dos agentes presentes na natureza que podem propiciar a deterioração de parte da tubulação, caso não sejam tomadas ações preventivas, tornando as instalações susceptíveis a acidentes operacionais. Sendo assim, o vazamento de um fluido ao meio externo figura como um dos problemas mais sérios na indústria de petróleo, acarretando prejuízos ecológicos e financeiros. O vazamento pode apresentar diversas manifestações de sinais característicos, variação da queda de pressão na posição do vazamento, entre outros parâmetros. As técnicas de detecção de vazamentos disponíveis vão desde a observação visual até a modelagem matemática através de técnicas computacionais. Neste sentido, o presente trabalho propõe investigar numericamente o escoamento bifásico, de uma corrente de óleo, contendo água, em oleodutos com conexões curvadas na presença de vazamentos. Todas as simulações foram realizadas utilizando o pacote comercial Ansys CFX adotando o modelo de partícula para descrever o escoamento bifásico óleo-água e adotando o modelo de turbulência SST em regime transiente. Os resultados das simulações demonstraram que a velocidade de entrada da mistura multifásica exerce influência sobre a queda de pressão no duto na presença do vazamento, onde percebeu-se a existência de uma relação direta entre o aumento da velocidade e a queda de pressão no duto devido ao vazamento.

Oil transport is used mainly by pipeline networks to transport oil from refineries and distributions points to the consumers. This is the main way to transport oils especially in areas of difficult access, ensuring efficiency, lowest cost and safety. In the chemical and petroleum industry it is possible to observe the presence of leak in the pipes, which has stimulated the development of reliable techniques for the rapid and accurate detection of leaks along the pipe in order to eliminate or minimize loss and environmental damage. In this context, this study aims to evaluate the effect of the numerical presence of leakage of two-phase flow (oil-water) pipe connections using the commercial software ANSYS CFX. The results from the fields of pressure, velocity and volume fraction are presented and assessed for illustrating the effect of the presence of the leak in the dynamic flow in the pipe with a curved connection.