BR 
EN Centrifugal pumps are present in the daily life of human beings. They are essential to several industrial processes that transport single- and multi-phase flows with the presence of water, gases, and emulsions, for example. When pumping low-viscous liquids, the flow behavior in impellers and diffusers may affect the centrifugal pump performance. For these flows, complex structures promote instabilities and inefficiencies that may represent a waste of energetic and financial resources. In this context, this paper aims at characterizing single-phase water flows in one complete stage of a centrifugal pump to improve our understanding of the relationship between flow behavior and pump performance. For that, a transparent pump prototype was designed, manufactured and installed in a test facility, and experiments using particle image velocimetry (PIV) were conducted at different conditions. The acquired images were then processed to obtain instantaneous flow fields, from which the flow characteristics were determined. Our results indicate that the flow morphology depends on the rotational speed of the impeller and water flow rate: (i) the flow is uniform when the pump works at the best efficiency point (BEP), with streamlines aligned with the blades, and low vorticity and turbulence in the impeller; (ii) the velocity field becomes complex as the pump begins to operate at off-design conditions, away from BEP. In this case, velocity fluctuations and energy losses due to turbulence increase to higher numbers. Those results bring new insights into the problem, helping validate numerical simulations, propose mathematical models, and improve the design of new impellers.
Autor: João Lucas Braga Da Silva
Optimization of design variables and control rules in field development under uncertainty: A case of intelligent wells and CO2 water alternating gas injection
This paper focuses on life-cycle optimization of oil field development plan under uncertainty. The optimization problem included a wide range of design variables and control rules related to wells and platform in a realistic benchmark case (UNISIM–II–D) with a known ground truth reservoir model, UNISIM–II–R, that resembles Brazilian pre-salt fractured carbonate reservoirs in their early development stage. The design variables were the number and location of wells, the fluid processing capacity of the platform, and the location of internal control valves (ICVs), whereas the control rules were the setting of ICVs, production and injection rates, and the duration of the water-alternating-gas (WAG-CO2) cycle. An iterative sequential optimization framework was developed to deal with the massive search space and complex parameterization. The optimization further took into consideration the subsurface, operational and economic uncertainties, and used iterative discrete Latin hypercube method as the search algorithm. The robust optimization was carried out on a subset of representative models derived from the reduction of a large ensemble of data-assimilated models. As a low-fidelity representation of the compositional fluid model, a black-oil model was used to reduce simulation runtime. To validate our optimization framework, we applied the optimal development strategy to the ensemble of compositional simulation models, as well as the ground truth model. The true model’s responses were within the ranges predicted by the compositional ensemble, confirming the optimization framework’s reliability. The general methodology developed in this study, as well as our findings, can be used to optimize other similar real-world complex and high-risk field development projects, and are especially useful in closed-loop field development and management practices.
Binary well placement optimization using a decomposition-based multi-objective evolutionary algorithm with diversity preservation
In binary multi-objective well placement optimization, multiple conflicting objective functions must be optimized simultaneously in reservoir simulation models containing discrete decision variables. Although multi-objective algorithms have been developed or adapted to tackle this scenario, such as the derivative-free evolutionary algorithms, these methods are known to generate a high number of duplicated strategies in discrete problems. Duplicated strategies negatively impact the optimization process since they: (i) degrade the efficiency of recombination operators in evolutionary algorithms; (ii) slow the convergence speed as they require more iterations to find a well-distributed set of strategies; and (iii) perform unnecessary re-evaluations of previously seen strategies through reservoir simulation. To perform multi-objective well placement optimization while avoiding duplicated strategies, this paper investigates the application of a newly proposed algorithm named MOEA/D-NFTS, with a modified diversity preservation mechanism that incorporates prior knowledge of the problem, on a multi-objective well placement optimization problem. The proposed methodology is evaluated on the UNISIM-II-D benchmark case, a synthetic carbonate black-oil simulation model in a well placement optimization problem using a binary strategy representation, indicating the presence or absence of a given candidate well position in the final strategy. The objective functions are the maximization of the Net Present Value, the maximization of the Cumulative Oil Production, and the minimization of Cumulative Water Production. The modified MOEA/D-NFTS performance is compared with a baseline algorithm without diversity preservation, and the evidence shows that the MOEA/D-NFTS produces statistically significant superior results, and is suitable for binary multi-objective well placement optimization.
Prototyping visualizations as a support for selecting representative models of petroleum reservoirs
by Miguel Angelo Mena Póvoa, Samuel Oliveira Da Silva, Celmar Guimarães da Silva, presented at CGVCVIP 2023, June 2023.
Abstract
Petroleum engineers usually create a set of hundreds of models of a given oil reservoir under analysis to represent its uncertainties. Assisted optimization approaches may help engineers to select a subset of these models (a.k.a. representative models, or RMs for short), which is used in computational flow simulations in replacement of the original set, aiming to reduce the total simulation runtime without changing the quality of these results. Despite the power of visualization techniques to help people to understand multidimensional datasets like the ones provided in this scenario, we noted a few efforts that use these techniques to help petroleum engineers to assist the selection of RMs. In this context, our research aims to test the hypothesis that it is possible to improve how interactive visualization resources are currently used to aid decision-making regarding the selection of RMs, mainly in the presence of multiple sets of RMs or multiple variables (obtained from running model simulations). This work presents our first steps towards this goal: (a) literature review and (b) definition of visualization prototypes that aim to help the analysis of RMs regarding the values of the variables provided by simulation outputs, and the risk curves associated with these variables. As preliminary results, we present our proposed interactive visualizations and briefly point out the design rationale behind these prototypes.
Experimental Investigation Of The Shear Effect On Oil-Water Emulsion Flow In Pipelines
by Natan Augusto Vieira Bulgarelli, , Jorge Luiz Biazussi, William Monte Verde, Antonio Carlos
Bannwart, Marcelo Souza de Castro, presented at HTFF 2022, August 2022.
Abstract
Emulsion flows have been a severe flow assurance issue, mainly in mature oil fields. Its formation occurs due to shear on oil-water flows caused by artificial lift methods, such as Electrical Submersible Pumps (ESP), and/or valves. The shear rate has an important role in emulsion flow behavior related to its relative viscosity and phase inversion. Therefore, this work presented an experimental investigation of the shear effect on three emulsion systems flowing in a pipeline. The shear element used was a combination of an 8-stage ESP and a glob valve. The emulsion systems analyzed were unstable emulsion and stable emulsion with and without a demulsifier. The experimental investigation was carried out for two ESP rotational speeds, 2400 and 3500 rpm, and one total volumetric flow rate, varying the water cut. From this study, it was observed that phase inversion occurred with increasing shear. Moreover, the effective viscosity was the same regardless of the surfactant presence for the three emulsion systems tested.
Flow Visualization In The Impeller And Diffuser Of A Centrifugal Pump Using Time-Resolved Particle Image Velocimetry
by Rodolfo M. Perissinotto, William D.P. Fonseca, Rafael F.L. Cerqueira, William Monte Verde, Jorge L. Biazussi, Erick M. Franklin, Antonio C. Bannwart, Marcelo S. Castro, presented at HTFF 2022, August 2022.
Abstract
The present paper describes an experimental study on the flow dynamics within a centrifugal pump impeller. A transparent pump prototype made of acrylic parts was firstly developed for flow visualization purposes. Then, single-phase flow experiments were conducted in different impeller rotational speeds and water flow rates. A time-resolved particle image velocimetry (TR-PIV) system was used as the flow visualization method. As a result, velocity fields were obtained in the whole impeller. They reveal that the flow behaviour is dependent on the pump operational condition. When the pump works at the best efficiency point (BEP), the flow is uniform and the streamlines follow the blade curvature. However, when the machine works at off-design conditions, the flow becomes complex, with the presence of turbulent structures which cause a reduction in the pump performance. This type of result may be useful to validate numerical simulations and support the proposition of new mathematical models, new impeller geometries, among other applications.
Visualization Of Oil-Water Emulsion Formation In A Centrifugal Pump Stage
by Rodolfo Marcilli Perissinotto, Rafael Franklin Lazaro de Cerqueira, William Monte Verde, Jorge Luiz Biazussi, Antonio Carlos Bannwart, Marcelo Souza de Castro, presented at TPS 2022, 2022.
Abstract
Electrical submersible pumps are assembled in oil wells to act as artificial lift methods. When water is present in the reservoir, oil-water emulsions are formed in the pump. These two-phase mixtures affect the performance and promote instabilities that lead the machine to operate inefficiently and fail prematurely. Therefore, this paper aims to investigate the formation of emulsions and behavior of mineral oil drops in a transparent centrifugal pump through a flow visualization approach. Shut-off, best efficiency point, and open-flow condi tions are investigated at three impeller rotational speeds with high-speed imaging and particle image velocimetry. As the oil fraction increases, large drops accumulate in the impeller channels, while some escape to the volute and circulate until the water flow carries them out of the pump stage. Regions with vortices and water recirculation explain the accumulation of oil drops in the impeller and reduced pump performance at low water flow rates. Intense velocity fluctuations at the impeller and impeller-volute boundary indicate the main causes for oil drop rotation, deformation, and fragmentation at high water flow rates. The new findings can be used to improve models and numerical simulations for pumps operating with multiphase flows and help the creation of new pump designs.
Evaluation of the effect of wax concentration in crude oils on the dimensionless temperature plateau
by Letícia Bizarre, Ivanei F. Pinheiro, Charlie van der Geest, Vanessa C. B. Guersoni, Aline Melchuna, presented at SPE FATC 2022, November 2022.
Abstract
One of the main challenges regarding crude oil production under low temperatures in deep seas concerns
the wax deposition in pipelines. This issue presents a high level of complexity and the governing mechanism
is still under investigation. Considering the deposition phenomenon and seeking to improve the knowledge
about the governing mechanism and the main variables influencing the final behavior, the present work
analyzes how different oil compositions and mixtures, under different flow conditions, impact the deposit wax
thickness. It also compares the dimensionless temperature for different wax concentrations, which allows to
evaluate the behavior of the temperature gradient, and verifies the behavior of the plateau under different
Reynolds numbers. Finally, the mechanism proposed in this work is compared with the behavior proposed by
the main governance mechanisms discussed in the literature in the last decades.
Experimental Investigation on Velocity Fields, Vorticity, and Turbulence within the Stage of an Electrical Submersible Pump (ESP)
by Rodolfo M. Perissinotto, William D.P. Fonseca, Rafael F.L. Cerqueira, William Monte Verde, Jorge L. Biazussi, Erick M. Franklin, Antonio C. Bannwart, Marcelo S. Castro, presented at SPE FATC 2022, November 2022.
Abstract
This paper presents an experimental study on the flow dynamics within an Electrical Submersible Pump (ESP) stage. An ESP prototype with transparent impeller and diffuser was designed and manufactured to allow flow visualization, which was achieved by using a Time-Resolved Particle Image Velocimetry (TR-PIV) system. Single-phase water flow tests were conducted in various flow rates corresponding to percentages of the Best Efficiency Point (BEP). The average velocity fields, vorticity contours, and turbulent kinetic energy values obtained in the whole impeller reveal that the flow behaviour is very dependent on the ESP operational condition. Energy losses due to turbulence are lower when the pump works at the BEP. But when the device operates at off-design conditions, the flow becomes complex, with high vorticity and turbulence which cause a reduction in the performance. This type of investigation may be useful to validate numerical simulations, support the proposition of mathematical models, or help create improved impeller designs.