In the present paper, a dynamical signal analysis of oil-water dispersion is presented. The focus is on phase inversion physics and the associated dynamical features of collected signals from an acoustic receptor placed within a flow setup where phase inversion where triggered when needed. The acoustic fields associated with the mixing system showed clear differences between oil continuous and water continuous media, phase inversion could be clearly identified from the acquired sensor signals. The dynamical analysis of the experimental data showed characteristic frequency transitions as well as specific attractors. The analysis tools could be used in field application to monitor oil-water flows for flow assurance purposes.
Fluid flow invasion is governed by the characteristics of the pore structure in the porous media. The flow is restricted due to the increase of net stresses near borehole after drilling. Understanding the fluid flow at the pore scale becomes an important aspect of successful operations such as matrix acidizing or fluid formation treatment. The aim of this work is to demonstrate the ability of using Lattice-Boltzmann formulations to solve the complex fluid flow system in the porous medium as compared to a Darcy type of flow analysis using geomechanical approaches. The simulations were performed at the same physical scale. The reduction of pore size at the vicinity of the borehole is approximated using different geometrical domains to mimic the fluid invasion process as a result of change in net stresses.
The present paper is concerned with an experimental study of the acoustic signature of phase inversion in an oil-water mixture system. The system studied was used to correlate the process of phase inversion with the acoustic field generated during the two fluid mixing. The experimental results revealed that the relation between the acoustic fields produced by a water continuous dispersion and the phase inversion has a clear and different signature from an oil-continuous system using a batch mixing system. This dynamical characteristic of the phase inversion phenomenon could be of use in practical systems to detect phase inversion when it occurs based on the acoustic field measured in the subject process.
In this paper we focus on electrical-submersible-pump (ESP) failure caused by scale buildup. Weak fluctuations recorded in the motor current signals several weeks before a failure indicate a change in the motor load. Advanced signal analysis of the motor current data reveals the presence of a dynamic characteristic in the ESP signal during rapid scale buildup in the pump stages. On the basis of the raw data from the motor current draw, a dynamic cascade can be identified in the current marked with the superimposition of several characteristic frequencies added over time that develop into a chaotic trend. Our analysis was conducted with different signal-processing tools, such as Fourier transform, wavelet transform, and chaotic attractors, which described the nature of the scale signature in the current logs. This analysis was the first step toward developing a real-time diagnostic tool for predicting ESP failures.
The present study is devoted to the flow peoperties of a vortex shedding system behind a bluff body that has a crescent cross-section, facing downstream of the flow. The investigation is conducted numerically using a lattice Boltzmann method. As a benchmark validation, the studied system was compared to the system of vortices formed behind the classical case of a circular cylinder for the same flow configuration and dynamic conditions, while varying the Reynolds number. The flow simulations have revealed that the crescent body affected substantially the shedding mechanism with remarkable differences when compared to the classical cylindrical case. There was a clear decrease in the shedding frequency with the crescent body that is beneficial when using this system as a metering tool.
The vortex shedding flow system had, and still has, a lot of interest from researchers in fluid dynamics due to its many applications for flow metering purposes, for studies of vortical flows or as a benchmark case for numerical methods (Tuann and Olson, 1978; Loc, 1980; Coutanceau & Defaye, 1991; Lakshmipathy, 2004; Reich et al., 2005). The Von-Karman vortex system, known as vortex shedding, occurs when a flow passes around a bluff body, classically cylindrical. To investigate different aspects of the vortex shedding, bluff bodies with different shapes were studied both experimentally and numerically.
The flow behind a circular cylinder is classicaly supposed symmetric at low Reynolds numbers in the range of 70 to 100. When Reynolds number increases, the flow begins separating just at the downstream edge of the cylinder and forms an alternating system of vortices with a constant shedding frequency. This phenomenon has been used as means to measure flow rates with a high accuracy due to its low cost and low maintenance, and being not sensitive to physical properties of the fluid flows measured. Therefore, this metering method has been used in several industries to measure flow rates of liquids, gases and steam flows over a large interval of Reynolds numbers. From the fundamental point of view, this flow system was investigated numerically by many authors. One of first authors was Payne (1958) who studied this flow system for Reynolds numbers below 100 and characterized in details the shedding system in this flow rates range.
Electrical submersible pumps (ESPs) are subject to several failure modes that are well documented in the industry. Startup conditions have seen a lot of improvement over the past decade, with new generations of the variable speed drive (VSD) and controllers avoiding harmful frequencies to the system. Subsequently, ramping protocols are important to achieve safe and optimal pump operation. The present paper discusses the requirements to achieve a smooth and reliable startup of ESPs based on dynamical considerations. The analysis evaluates both mechanical and electrical constraints and their implications on a safe ramping procedure. It was found that a combination of different loads on the pump shaft can result in unwanted dynamical loads that could compromise the pump's operational reliability. It is shown that startup protocols close to the natural motor resistance are beneficial for a smooth and reliable rampup without compromising the system's stability.
This paper presents the methodology of correcting the erroneous reading of the venturi meters for measuring the gas rate when high amounts of liquids, including condensate and water, are being produced from the gas wells. The proposed system takes advantage of existing infrastructure in proximity of the venturi meters and is designed to be retrofitted to the existing meters to knock out the liquid before the meter and recombines it after. This method eliminates the need for an additional flow line to carry out the liquid or a compressor to reinject the separated liquid back into the pressurized gas line.
The present work is concerned with a numerical investigation of a hybrid flow metering system that relies on a combination of bluff bodies and orifice plates to minimize process noise effects and have better accuracy measurements. The system is designed for liquid flows comprising different water and oil compositions in a flowline. In the flow simulations, the mesoscopic approach used based on lattice Boltzmann formulations has revealed the existence of a flow instabilities that generate a fluctuation mechanism with a characteristic frequency proportional to the flow rate and that has high amplitude and lower band value compared to conventional vortex shedding meters.
Vortex shedding behind circular cylinders is a well-known phenomenon that generates a succession of vortices known as the Von Karman street. In a commercial vortex shedding meter, different bluff body configurations and flow settings are used. The Von Karman street is a description of alternating vortices that form under certain dynamic conditions behind shaped obstacles and has been studied in both fundamental and applied aspects. The shedding frequency of the vortices is directly proportional to the flow rate, and by measuring the shedding frequency, accurate determination of the flow rate with proper calibration can be achieved. The Von Karman flow instability is defined over a certain range of Reynolds number and has been studied for structure reliability to remove any mechanical stress on specific designs (Venugopal et al. 2011; Mittal and Raghuvanshi 2001; Pier 2002). In flow measurements, there are several industrial vortex meters based on vortex shedding in gas, steam, or liquid flows. In theory, the frequency is non-sensitive to the physical properties of the fluid such as density, viscosity, temperature, pressure, and conductivity within a range of Reynolds numbers. A vortex-shedding meter is usually calibrated once for measuring steam, gas, or liquids, which applies over the specified volumetric flow velocity ranges. One of major problems faced by vortex shedding meters in process lines is the noise generated from pumps, compressors, steam traps, valves, etc., that may affect the meter to readings resulting in an over estimate of the frequency values. This will result in wrong readings in the flow rates especially when measuring gas streams. To mitigate process noise effect, filtering circuitries are usually used and, as a result, the dynamic range of the meter decreases. In the study of the vortex shedding mechanism, computational flow modeling was used extensively. In the last decade, Lattice Boltzmann mesoscopic formulations have shown considerable advantages compared to the Navier-Stokes formulations for their simplicity and being able to model fluid flows over a large flow application. The present paper discusses a flow measurement simulation of an oil-water mixture through an orifice plate using a mesoscopic flow formulation. In the simulations, the two-phase mixture is considered homogenous. The results show the effect of the orifice plate geometry on the flow profiles and the flow parameters such as pressure and measurement efficiency.
The simulated flow system comprises a circular pipe in which a cylindrical bluff body is inserted in the middle. Behind the bluff body an orifice plate is placed at a distance equivalent to the diameter of the cylindrical body as shown in Fig. 1.
The flow system is assumed to be axisymmetric and 2D representation of the system is investigated numerically to study the flow structure behind the combination cylinder/orifice.