EN 
BR Methods for flow visualization have been decisive for the historical development of fluid mechanics. In recent years, technological advances in cameras, lasers, and other devices improved the accuracy and reliability of methods such as High-Speed Imaging (HSI) and Particle Image Velocimetry (PIV), which have become more efficient in visualizing complex transient flows. Thus, the study of centrifugal pumps now relies on experimental techniques that enable a quantitative characterization of single- and two-phase flows within impellers and diffusers. This is particularly important for oil production, which massively employs the so-called Electrical Submersible Pump (ESP), whose performance depends on the behavior of bubbles and drops inside its impellers. Visualization methods are frequently used to study gas-liquid flows in pumps; however, the visualization of liquid-liquid dispersions is complex and less common, with few publications available. Methods to characterize the motion of gas bubbles are often unsuitable for liquid drops, especially when these drops are arranged as emulsions. In this context, there is room to expand the use of visualization techniques to study liquid-liquid mixtures in pumps, in order to improve the comprehension of phenomena such as effective viscosity and phase inversion with focus on the proposition of mathematical models, for example. This is a main motivation for this paper, which presents a review of researches available in the literature on flow visualization in centrifugal pumps. A broad set of studies are reported to provide the reader with a complete summary of the main practices adopted and results achieved by scientists worldwide. The paper compares the methods, investigates their advantages and limitations, and suggests future studies that may complement the knowledge and fill the current gaps on the visualization of single-phase flows, gas-liquid, and liquid-liquid mixtures.
Tag: EPIC
Disciplina de Pós-Graduação em Captura, Uso e Armazenamento de Carbono
O EPIC, convida todos para a aula inaugural da disciplina que oferecerá no primeiro semestre de 2021. O tema desta primeira aula será “Energy scenario, diversification and transition to a low carbon society”, que será ministrada por Rannfrid Skjervold, da Equinor, e Asgeir Tomasgard, da NTNU.
Esta aula inaugural acontecerá dia 18/03/2021, às 9hs (BRT). Mais informações podem ser obtidas no banner abaixo.
Experimental investigation on the performance of Electrical Submersible Pump (ESP) operating with unstable water/oil emulsions
Electrical Submersible Pump (ESP) is one of the most commonly used artificial lift methods in petroleum production, due to its capacity to operate in several conditions with two or three-phase flows. When the ESP operates with emulsion flow, its performance is degraded, and operational instabilities occur. Therefore, this paper aims to carefully investigate phase inversion and to present, by the first time, the ffective viscosity of unstable mineral oil/water emulsions, both within the ESP. The first part of this work analyzes the phase inversion phenomenon for two oil types in three viscosities, five ESP rotational speeds, and three mixture flow rates. Logistic functions were fitted using the dimensionless head as a water cut function to determine the phase inversion within the ESP. The continuous phase inversion model, developed for emulsion pipe flow, did not present a satisfactory agreement to flow conditions tested. An indirect method to determine the emulsion effective viscosity within the ESP was proposed, which was obtained from the water/oil emulsion performance curves. The viscous performance data were used to determine the geometric coefficients of a dimensionless head empirical model for the tested ESP. Thus, the calculated values were compared with the effective viscosity obtained with oil and water emulsions, as well as the ESP performance, operating with emulsion and oil, which provides similar values for low rotational speeds. The different behavior of the effective viscosity between the pipeline flow and within the ESP was observed for water-in-oil emulsions and may be related to the high centrifugal field in the ESP.
Experimental analysis on the behavior of water drops dispersed in oil within a centrifugal pump impeller
This paper aims to investigate the behavior of water drops in an oil continuous medium inside a centrifugal pump impeller working at eight operational conditions (up to 1200 rpm and 2.8 m³/h) with two-phase liquid-liquid flows. Water-in-oil dispersions were produced with low water fractions around 1% in volume, thus the dispersed phase became arranged as water drops. Experiments for pump performance and flow visualization were conducted using a high-speed camera and a pump prototype with a transparent shell. Flow images revealed that the large water drops usually deform, elongate, and break up into smaller ones, especially at high pump rotations and oil flow rates, while small water drops tend to keep their spherical geometry without deformations and fragmentations. A sample of drops were tracked and their equivalent diameters, residence times, and velocities were calculated. The tracking indicated that the water drops travel random trajectories in the channels, generally undergoing a deceleration along their pathway. Furthermore, the residence times and the average velocities of water drops strongly depend on the flow conditions. For the conditions tested, the water drops presented equivalent diameters between 0.1 and 6.0 mm, average velocities from 0.4 to 1.7 m/s, and residence times between 30 and 152 ms. For a more complete analysis, the results achieved in this study are constantly compared with results available in literature regarding oil drops in oil-in-water dispersions.
Conference highlights EPIC's potential for innovation in the energy sector
On November 7, 2019, Unicamp's news outlet featured an article on the 1st EPIC Conference on its homepage.
The opening panel of the conference included FEM professor and EPIC director Antonio Carlos Bannwart; Luiz Nunes from Fapesp; Ruben Schulkes from Equinor; Alfredo Renault from the National Agency for Petroleum, Natural Gas, and Biofuels (ANP); and Unicamp's rector, Marcelo Knobel.
Scholars emphasized the importance of the partnership between academia and industry, which benefits both by producing highly qualified professionals, developing applied research, and creating opportunities for knowledge exchange between different sectors and countries.
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FAPESP and Equinor launch Petroleum Engineering Research Center at Unicamp
The launch of the Petroleum Engineering Research Center at Unicamp (EPIC) was featured on the Inova Unicamp website in February 20, 2019. The launching took place at FAPESP’s headquarters.
With a 10-year agreement, FAPESP and Equinor will each contribute around R$ 25 million over the first five years, with the same amount to be invested in the following five years. Another portion of the investment will come from Unicamp in the form of researcher and support staff salaries, infrastructure, and facilities.
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Opening of research center on sustainable oil use injects R$ 25 million into Unicamp
EPIC was featured on G1 on February 19, 2019. The article discusses how the center was established, the partner organizations (FAPESP, Equinor, and Unicamp), and the funding mechanisms. Additionally, it explores the collaboration between EPIC and CEPETRO and the scientific objectives of the center.
In an interview, Denis Schiozer, director of CEPETRO, stated: "We will seek to produce more oil in a more sustainable way and with innovative solutions for CO2 disposal, which can be used to increase oil production; and for a more sustainable use of the water produced along with oil," mentioning that the center will focus on oil reservoirs in the Campos Basin and the pre-salt layer.
Cepetro area, at Unicamp — Photo: Antonio Scarpinetti / Unicamp
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