Showing papers on "Multiphase flow published in 2006"

Equations of state in a lattice Boltzmann model

Abstract: In this paper we consider the incorporation of various equations of state into the single-component multiphase lattice Boltzmann model. Several cubic equations of state, including the van der Waals, Redlich-Kwong, and Peng-Robinson, as well as a noncubic equation of state (Carnahan-Starling), are incorporated into the lattice Boltzmann model. The details of phase separation in these nonideal single-component systems are presented by comparing the numerical simulation results in terms of density ratios, spurious currents, and temperature ranges. A comparison with a real fluid system, i.e., the properties of saturated water and steam, is also presented.

Streamline-based simulation of carbon dioxide storage in a North Sea aquifer

Abstract: [1] We model carbon dioxide (CO2) storage into a deep North Sea aquifer using streamline-based simulation. We assume incompressible flow of liquid-like CO2 and aqueous phases. We simulate dissolution of CO2 and a rate-limited precipitation reaction. Advective transport and reactions are solved along streamlines, while dispersion and flow due to gravity segregation of the phases are solved on the underlying grid. Geological storage is modeled on a one million cell model. The distribution of CO2 after injection is dominated by advective transport due to multiphase flow, and CO2 moves preferentially through high-permeability channels. Without reaction the regional groundwater flow causes the CO2 to continue to migrate until it reaches residual saturation, where it continues, slowly, to dissolve. Precipitation leads to a decrease in porosity and permeability, while CO2 is stored in the solid phase. The storage efficiency is low, around 2%, because of aquifer heterogeneity.

RF sensor for multiphase flow measurement through an oil pipeline

Abstract: We have developed, in conjunction with Solartron ISA, an electromagnetic cavity resonator based sensor for multiphase flow measurement through an oil pipeline. This sensor is non-intrusive and transmits low power (10 mW) radio frequencies (RF) in the range of 100–350 MHz and detects the pipeline contents using resonant peaks captured instantaneously. The multiple resonances from each captured RF spectrum are analysed to determine the phase fractions in the pipeline. An industrial version of the sensor for a 102 mm (4 inch) diameter pipe has been constructed and results from this sensor are compared to those given by simulations performed using the electromagnetic high frequency structure simulator software package HFSS.

Experimental Analysis of Multiphase Flow in Metallic foam: Flow Laws, Heat Transfer and Convective Boiling

Abstract: Permeability and inertial coefficient are obtained using stationary pressure profile measurement in a channel filled with various metallic foams. Compressibility effects are studied. In single phase, heat transfer is X 100 with only a limited increase of pressure drop. Convective boiling regime showed significant heat transfer enhancement with very low-pressure drop. Global flow behavior across the test section is described by ID homogeneous model.

Comparison of Computational Results Obtained From a Homogeneous Cavitation Model With Experimental Investigations of Three Inducers

Abstract: The paper presents full 3D numerical simulations and experimental investigations of the cavitating flow through three axial inducers. These inducers are identified by the tip blade angle at the leading edge β 1T =8, 10, and 13 deg. The numerical and experimental investigations were carried out at the LEMFI laboratory (Laboratoire d'Energetique et de Mecanique de Fluides Interne) of the ENSAM-Paris center (Ecole rationale Superieure d'Arts et Metiers). A review of the cavitating regime modeling and the cavitation homogeneous model used for this paper's calculations is first presented. The numerical model is based on a combination of the multiphase flow equations with a truncated version of the Rayleigh-Plesset model predicting the complicated growth and collapse processes of bubbles. The mass transfers due to cavitation are source/sink terms in continuity equations of the liquid and vapor phases

An apparatus and method for measuring a parameter of a multiphase flow

Abstract: An apparatus is provided that determines a characteristic of a multiphase fluid, such as an aerated oil and water fluid, flowing within a pipe. The apparatus includes a fluid flow meter, a water cut meter, and a density meter, wherein the density meter determines the density of the fluid flow to determine the gas volume (or void) fraction of the multiphase fluid flow. The output signal of each of the meters is provided to a multiphase flow model to provide a plurality of multiphase parameters, such as phase fraction, volumetric flow, mass flow of each of the phases of the multiphase mixture, optimized for various flow conditions. Each of the meters may be secured to the outer surface of the pipe using various means, such a clamping means.

Annular Centrifugal Contactors—A Review

Abstract: The annular centrifugal contactors based on the Taylor-vortex flow have a great potential in chemical, nuclear, metallurgy and biotechnology industry. This equipment has been extensively studied during the past 80 years. However, most of the research has been focused on the flow instabilities. Relatively scanty information is available on the detailed quantitative flow pattern in single and multiphase flows, mixing and axial mixing, mass and heat transfer coefficients, drop and bubble size distribution, and so on. The published literature on these aspects has been critically analysed and presented in a coherent manner. Recommendations have been made for correlations which can be used for design purpose; lacunae in the available literature have been delineated and specific recommendations have been made for further work.

Dissipative particle dynamics with attractive and repulsive particle-particle interactions

Abstract: In molecular dynamics simulations, a combination of short-range repulsive and long-range attractive interactions allows the behavior of gases, liquids, solids, and multiphase systems to be simulated. We demonstrate that dissipative particle dynamics (DPD) simulations with similar pairwise particle-particle interactions can also be used to simulate the dynamics of multiphase fluids. In these simulations, the positive, short-range, repulsive part of the interaction potentials were represented by polynomial spline functions such as those used as smoothing functions in smoothed particle hydrodynamics, and the negative long-range part of the interaction has the same form but a different range and amplitude. If a single spline function corresponding to a purely repulsive interaction is used, the DPD fluid is a gas, and we show that the Poiseuille flow of this gas can be described accurately by the Navier-Stokes equation at low Reynolds numbers. In a two-component system in which the purely repulsive interactions between different components are substantially larger than the purely repulsive intracomponent interactions, separation into two gas phases occurs, in agreement with results obtained using DPD simulations with standard repulsive particle-particle interactions. Finally, we show that a combination of short-range repulsive interactions and long-range attractive interactions can be used to simulate the behavior of liquid drops surrounded by a gas. Similar models can be used to simulate a wide range of processes such as multiphase fluid flow through fractures and porous media with complex geometries and wetting behaviors.

A Comprehensive Procedure to Estimate Erosion in Elbows for Gas/Liquid/Sand Multiphase Flow

Abstract: A comprehensive procedure that combines mechanistic analysis and numerical simulation approaches is proposed to estimate the erosion in elbows for gas/liquid/sand particle multiphase flow systems. The erosion problem in multiphase flow is approximately transferred to one in single-phase flow by introducing the effective sand mass ratio and a representative single-phase flow to which a single-phase computational-fluid-dynamics-based erosion-prediction model can be applied. Erosion in elbows is calculated for various multiphase flow patterns and compared to experimental data in the literature. Reasonable agreement between the simulations and the literature data is observed. The proposed approach is an effective tool to estimate the erosion in multiphase flow.

Systems and Methods For Measuring Multiphase Flow in a Hydrocarbon Transporting Pipeline

Abstract: This disclosure relates in general to methods and systems for measuring multiphase flows in a pipeline using a combination of venturi, microwave and radiation techniques, where the pipeline is configured to transport hydrocarbons. More specifically, but not by way of limitation, certain embodiments of the present invention provide methods and systems in which low activity radiation sources may be used in combination with one or more microwave transmitter-receiver pairs and pressure differential sensors to measure the flow rates and fractions of phases in multiphase flows in a pipeline, such as may be encountered in producing hydrocarbon wells. Additionally, other embodiments of the present invention provide for the arrangement of one or more microwave transmitter-receiver pairs, one or more radiation source-detector pairs and/or one or more pressure sensor ports in the same cross-section of the throat of a venturi to measure multiphase flow in a hydrocarbon transporting pipeline.

Well Modeling in the Multiscale Finite Volume Method for Subsurface Flow Simulation

Abstract: A multiscale method for effective handling of wells (source/sink terms) in the simulation of multiphase flow and transport processes in heterogeneous porous media is developed. The approach extends the multiscale finite volume (MSFV) framework. Our multiscale well model allows for accurate reconstruction of the fine‐scale pressure and velocity fields in the vicinity of wells. Accurate and computationally efficient modeling of complex wells is a prerequisite for field applications, and the ability to model wells within the MSFV framework makes it possible to solve large‐scale heterogeneous problems of practical interest. Our approach consists of removal of the well singularity from the multiscale solution via a local change of variables and the computation of a smoothly varying background field instead. The well effects are computed using a separate basis function, which is superposed on the background solution to yield accurate representation of the flow field. The multiscale well treatment accounts for b...

Modelling of saturated sand flux

Abstract: We derive a saturated sand flux model based on the previous models of Sauermann et al (2001 Phys. Rev. E 64 0313005) and Sorensen (2004 Geomorphology 59 53) and determine its parameters, as a function of the grain and fluid properties, from a comparison with wind tunnel data. We also show that dunes simulated with the new sand transport model compare well with observations of Moroccan dunes.

Multiphase Processes in Porous Media

Abstract: Models for multiphase flow in porous media are widespread today and can be found in many places in science and engineering. More complex multiphase-multicomponent models that even allow phase changes to occur need sophisticated numerical algorithms. Research in this area has been very successful with a versatile result.

Simulations of Solid-Propellant Rockets: Effects of Aluminum Droplet Size Distribution

Abstract: Flow modeling and simulation of solid-propellant rockets from first principles is quite challenging with several physical problems, including complex evolving geometries, turbulence, and multiphase flow with a chemically reactive disperse phase. To this end, a flexible simulation framework has been developed, in which multiphase flow computations are performed that include three-way coupling between phases (mixture-droplet-smoke), conservative coupling approach, and full heat release for the burning mechanisms. Results obtained from computations with burning aluminum droplets generating aluminum-oxide smoke are described for a generic rocket geometry. The effects of injected droplet size distribution obtained with two models are investigated and show the sensitivity of these distributions to the chamber flow dynamics, primarily at the nozzle inlet. The residence time and burning droplet diameter are verified by comparison with simple analytical predictions.

Operator based multiscale method for compressible flow

Abstract: Multiscale methods have been developed for accurate and efficient numerical solution of flow problems in large-scale heterogeneous reservoirs. A scalable and extendible Operator Based Multiscale Method (OBMM) is described here. OBMM is cast as a general algebraic framework. It is natural and convenient to incorporate more physics in OBMM for multiscale computation. In OBMM, two operators are constructed: prolongation and restriction. The prolongation operator is constructed by assembling the multiscale basis functions. The specific form of the restriction operator depends on the coarse-scale discretization formulation (e.g., finitevolume or finite-element). The coarse-scale pressure equation is obtained algebraically by applying the prolongation and restriction operators to the fine-scale flow equations. Solving the coarse-scale equation results in a high quality coarse-scale pressure. The fine scale pressure can be reconstructed by applying the prolongation operator to the coarse-scale pressure. A conservative fine-scale velocity field is then reconstructed to solve the transport (saturation) equation. We describe the OBMM approach for multiscale modeling of compressible multiphase flow. We show that extension from incompressible to compressible flows is straightforward. No special treatment for compressibility is required. The efficiency of multiscale formulations over standard fine-scale methods is retained by OBMM. The accuracy of OBMM is demonstrated using several numerical examples including a challenging depletion problem in a strongly heterogeneous permeability field (SPE 10).

A Multiple-Continuum Approach For Modeling Multiphase Flow in Naturally Fractured Vuggy Petroleum Reservoirs

Abstract: Author(s): Wu, Y.-S.; Qin, Guan; Ewing, Richard E.; Efendiev, Yalchin; Kang, Zhijiang; Ren, Yulin | Abstract: The existence of vugs or cavities in naturally fractured reservoirs has long been observed. Even though these vugs can be largely attributed to reserves of oil, natural gas, and groundwater, few investigations of vuggy fractured reservoirs have been conducted. In this paper, a new multi-continuum conceptual model is developed, based on geological data and observations of core examples from carbonate formations in China, to investigate multiphase flow behavior in such vuggy fractured reservoirs. The conceptual model has been implemented into a three-dimensional, three-phase reservoir simulator with a generalized multi-continuum modeling approach. The conceptual model considers vuggy fractured rock as a triple-continuum medium, consisting of (1) highly permeable fractures, (2) low-permeability rock matrix, and (3) various-sized vugs. The matrix system may contain a large number of small or isolated cavities (of centimeters or millimeters in diameter), whereas vugs are larger cavities, with sizes from centimeters to meters in diameter, indirectly connected to fractures through small fractures or microfractures. Similar to the conventional double-porosity model, the fracture continuum is responsible for the occurrence of global flow, while vuggy and matrix continua, providing storage space, are locally connected to each other (and interacting with globally connecting fractures). For practical application of the multi-continuum concept in reservoir simulation, we propose a novel upscaling method for computing equivalent gridblock permeabilities of coarse blocks containing large isolated vugs, in which the local problems consisting of Darcy and Stokes flows are solved. In addition, we describe an efficient boundary condition for accurate computation of upscaled permeabilities. In the numerical implementation, a control-volume, integral finite-difference method is used for spatial discretization, and a first-order finite-difference scheme is adapted for temporal discretization of governing flow equations in each continuum. The resulting discrete nonlinear equations are solved fully implicitly by Newton iteration. The numerical scheme is verified and applied to simulate water-oil flow through the fractured vuggy reservoirs of Tahe Oil Field in China.

A method and apparatus for tomographic multiphase flow measurements

Abstract: A method for determining the flow rates of a fluid comprising a multi-component mixture of a gas and at least one liquid in a pipe, the method comprising the following steps: a) the multi-component mixture flow is conditioned to create a symmetrical annular gas concentration flow condition, b) the density distribution and/or dielectric constant distribution in said symmetrical flow within a cross-section of the pipe is determined, c) a function describing the radial distribution of density and/or radial distribution of dielectric constant is determined, d) the velocity of the multi-component mixture is determined, e) the temperature and pressure are obtained, and, f) based on the knowledge of densities and/or dielectric constants of the components of the fluid mixture, and the result from the above steps a-e, the volume and/or mass flow rates of the gas and liquid components of the fluid mixture are calculated. An apparatus for performing the method is also disclosed.