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BR Polymer flooding, known for enhancing heavy oil displacement, may encounter efficiency-limiting physical phenomena. This work assesses the impact of key factors like viscosity, shear rate, and adsorption in field applications using a model-based approach on the EPIC001 case, a real offshore Brazilian heavy oil reservoir. In simulation results, increasing the displacing fluid viscosity using apparent or zero-shear functions, oil production and economic returns show improvements over waterflooding. The shear rate effect slightly increases oil production and enhances injectivity loss due to shear-thinning in polymer flow. However, modeling it increases computation costs, as it extends simulation run time from minutes to days, making it impractical for intensive processes like production optimization. An analysis of the method’s effectiveness shows that it varies based on the adsorption level considered. At its highest value, even with a higher oil recovery factor, the economic return was lower than using waterflooding. Combining shear rate and adsorption has a minimal impact on field indicators when compared to adsorption alone. This work enhances the comprehension of physical phenomena and non-Newtonian behavior in tertiary polymer flooding on heavy oil reservoirs and its impact on the production forecast. It also highlights important considerations for modeling-based procedures.
Author: João Lucas Braga Da Silva
Investigation on the effects of concentration and paraffin type on the rheological behavior of model oils
The intrinsic characteristics of crude oils, combined with the pressure and low temperature of the seabed, can lead to flow assurance problems, compromising production. The low temperature causes a decrease in the wax solubility, eventually reaching the wax appearance temperature (WAT). Precipitated crystals can cause deposition on the tube walls and can affect production as they increase the pressure drop, decreasing flow during production. Depending on molecular weight, molecular structure and carbon number distribution, waxes can be called macrocrystalline and microcrystalline. Macrocrystalline wax mainly has a carbon number distribution of approximately C20 to C40 and has a linear molecular structure, so hydrocarbons tend to form large plates. Microcrystalline wax generally has chains with carbon numbers between C30 to C70 and its crystals tend to form smaller crystals. In the present work, the impact on gel strength was evaluated as a function of wax type (macrostructure and microstructure), wax concentration and applied shear rate. Understanding these impacts makes it possible to improve the models of wax deposition and, consequently,
the methods of preventing and mitigating the phenomenon.
Influence of the interface chemical composition and its impact on droplet coalescence of water-oil emulsions
This work aims to understand the phenomenon of coalescence as a function of chemical and rheological characteristics (elasticity and viscosity) of the interfacial film. In this context, the goal is to study the effect of the different physicochemical variables related to emulsion and its influence on the energy barrier that separates the droplets from the isolated state to coalescence. For this, a pendant drop tensiometer was used to determine the coalescence time between the oil droplet and the oil-water interface, using commercial surfactants to establish a correlation of how the physicochemical characteristics of the interfacial film will influence the coalescence time between the he oil droplet and the oil-water interface .The preliminary results show that the brine concentration and the ion types present in brine impact directly on the coalescence time, due to changes on interfacial film properties, promoting a barrier to coalescence, and modification on mechanism of interactions of these systems.
Development of a transparent pump prototype for flow visualization purposes
The presence of emulsions in centrifugal pumps has always been a top issue for oil and gas exploration companies. These oil-water mixtures cause financial losses along the production chain, as they often induce pumps to operate in an unstable and inefficient manner. As there is a clear dependence between the pump performance and the flow arrangement in the impellers, this current paper aims to broaden the understanding on the behavior of emulsions inside the stage of a centrifugal pump. Thus, the paper describes the design and fabrication of a new transparent pump prototype for visualization purposes focused on academic studies. The new prototype is completely transparent, so it enables visual access and light entrance from the front and sides. Besides, the new pump is able to operate with twophase flows, since the dispersed phase can be injected directly into the impeller channels, through the shaft. Some tests were then conducted with this new prototype. They provided successful results which are presented and discussed here. Therefore, the new transparent prototype is an innovative alternative to help engineers and researchers investigate twophase flows in rotating and stationary pump parts.
Thermal and morphological evaluation of wax crystals: effect of solvent and wax concentration
Petroleum is a complex mixture of hydrocarbons varying from saturate, resins, asphaltenes and aromatics. Wax, also known as paraffin, normally refers to the range of n-alkanes in the crude oil with carbon numbers higher than 18. The waxes present in crude oils are divided into two categories: macrocrystalline wax, tends to form large plate-like crystals and, microcrystalline, tends to form solids with a lower degree of crystallinity. It has not been possible to establish a pattern that links the tendency of type of solvent and type of paraffin, due to the complexity of the wax crystal morphology. The objective of this research is to study the thermal properties of macro and microcrystalline paraffin under solubilization of several solvents through experimental techniques of DSC (Differential Scanning Calorimetry) and CPM (Cross Polarized Microscopy). The interaction of each type of n-paraffin in different solvents causes distinct influences on the crystal morphology and, consequently, influences on their thermal behavior. This study is relevant since elucidating this behavior helps to optimize deposition models and thus, define more effective mitigation resources in the problem of wax deposition.
Study of the influence of commercial emulsion breaker on the water/ oil interfacial properties
The aim of this research project is to study how commercial emulsion breakers affect the interfacial properties of water/ oil systems. For that, the studies will be focused on the properties of the interface such as interfacial tension, dilational and shear viscoelastic behavior. The characteristics of the interfacial film will be analyzed along with the results from kinetic studies of phase separation with emulsion breakers. The tension and rheological studies of the interface will be performed by using a Spinning drop Tensiometer (Dataphysics SVT-20N) and an interfacial rheology accessory for a rotational rheometer (Haake, Mars III). Each rheological system aims to getting different properties of the interface. The dilational technique provides information about the response of the system when the interfacial area is changed, i.e., the kinetics in which the system acts to bring the interface back to the equilibrium condition. On the other side, in the shear technique the interfacial area is kept constant and the mechanical properties of the interface are probed. Emulsion breakers can act by affecting the viscoelastic properties of the interfacial film built up of crude oil components with surface active properties, such as asphaltenes, resins and naphtenic acids. Thus, the focus of this research proposal is to investigate how emulsion breakers acts on the formation and establishment of the interfacial film and the relationship between the film physic-chemical properties and the efficiency of the emulsion breaker, looking for a microscopic understanding of the phase separation phenomenon of water/ oil emulsions induced by emulsion breakers. (AU)
Using an electrical submersible pump mechanical vibration and a Fourier convolution neural network to estimate the water cut in two-phase liquid-liquid flows
In oil exploitation, water in the production is common and increases with the field life. For oil production to be economically feasible, artificial lifting techniques may be required. In this context, electrical submersible pumps have been widely used to provide energy to the fluid for decades. Despite the recent development on ESP vibration signal usage, most studies use the vibration signal for fault diagnosis algorithm development. On the other hand, the water cut is essential to obtain several volumetric variables, such as the flow rate of each phase, the effective viscosity, and the pressure drop. This study aims to obtain an artificial neural network that correlates the ESP mechanical vibrations with the water-liquid ratio of an oil-water two-phase flow. The artificial neural network uses a Fourier convolution neural network architecture, where the convolutions are performed in the frequency domain rather than the time domain. The experimental data obtained resulted in a non-uniform dataset on different spatial projection, which significantly affected the data-driven technique performance. Then, by filtering out spaced experimental points and using only the samples inside the sample convex hull, it was possible to successfully obtain a regression between the ESP vibration spectrum and the water cut. The results showed that data filtering and selection were crucial for the artificial neural network performance.
A Droplet-Based Image Velocimetry Technique for the Measurement of Liquid Velocity Fields in Two-Phase Water-Oil Dispersion Flows
The present work describes a measurement technique to estimate the continuous liquid velocity fields in twophase water-oil dispersion flows. A transparent pump prototype made of acrylic was firstly developed and installed to enable the use of flow visualization and optical measurement techniques. Then, in the experiments, water droplets were injected into the impeller channels of the centrifugal pump, where a mineral oil with a viscosity of µo = 18.0 cP was used as the continuous phase. The two-phase water-oil dispersion flow was then filmed with a high-speed camera, and the water droplets were black-dyed for a better contrast with the white background. When injecting the water drops, breakage events were frequently observed due to turbulence and shear effects, resulting in the birth of small droplets with a size in the range from 100 µm to 500 µm. The occurrence of small water droplets in combination with the viscous continuous oil phase meant that those droplets could be assumed as tracer particles from the continuous phase. Therefore, by computing the
small water droplet velocities, it is possible to estimate the velocity field of the continuous oil phase within an acceptable error margin. This is the main idea of the technique presented in this work, which does not require the addition of intrusive tracer particles, and thus can be seen as a cheap and simple alternative to PIV in two-phase dispersions with continuous viscous phases. After a series of image processing steps, the small water droplets in the range from 100 µm to 500 µm are identified, and the PTV technique computes their instantaneous velocity. In order to assess the method capabilities, the PTV ensemble-averaged liquid flow rate is compared against experimental values from a Coriolis flowmeter installed in the experimental setup. The technique is then applied to study the flow within a pump impeller, resulting in similar flow patterns found in the literature for studies using LDV and PIV studies.
Development and assessment of a particle tracking velocimetry (PTV) measurement technique for the experimental investigation of oil drops behaviour in dispersed oil–water two-phase flow within a centrifugal pump impeller
The objective of the current work is to present the development of a Particle Tracking Velocimetry (PTV) algorithm for the analysis of oil drops behaviour in two-phase oil–water dispersions within a centrifugal pump impeller. The drop tracking was realized through high-speed camera images in a transparent pump prototype, which enabled the visualization of oil drops dispersed in water in all the impeller channels. The PTV algorithm is based on deep-learning techniques for image processing. The drops are detected by a combined U-Net and Convolutional Neural Network (CNN) method, with the former generating a binary image and the latter detecting valid oil drop contours. After detection, the Labelled Object Velocimetry (LOV) is adopted to calculate the instantaneous oil drop velocity. A synthetic image generator based on a Generative Adversarial Network (GAN) is then developed to assess the results from the U-Net, CNN, and LOV models. Additional validation studies are performed using the results from Perissinotto et al. (2019a). The results reveal that the presented deep-learning PTV algorithm is robust and provides consistent and reliable data for the dispersed oil phase in two-phase oil–water flows.