This work addresses the transportation of viscous crude oil as concentrated oil-in-water (O/W) emulsions flowing in a partially submerged onshore pipeline. The main goal of this study is to analyze the effects of inversion point of the water-in-oil emulsion in the pressure drop with the aid of Pipesim® software. Pressure drop is determined by applying the Dukler correlation (Taitel and Dukler, 1976) to represent dead oil viscosity as a function of temperature, and API density using the Hossain correlation (Hossain et al., 2005). The Brinkman model (Brinkman, 1952) is applied to calculate the viscosity of the emulsion, with the Brauner and Ullmann (2002) equation for the water cut off method (inversion point). The pipeline, of 3,600 m and 4 inches in diameter, transports the oil and consists of three sections. The first and third sections are above ground and are in contact with the external environment. The intermediate section is sitting on the river bed and is the critical part of the pipeline, once high heat losses are observed. The results of this 1D and non-isothermal problem show that water cuts of 5 and 6%, for low heat exchange and high heat exchange, respectively, make it possible to transport the oil, as an oil-in-water emulsion, through the entire extension of the pipeline. However, a water cut of 10% creates a high-pressure drop in the system, assuring the movement of the fluid in long sections without compromising the system operation. The use of isolation influences the temperature gradient but doesn’t have a high influence on pressure gradient compared to emulsions.

The extraction of oil results in problems such as the scale formation in the various stages of the production process. The scale reduces all or part of the flow conduits, increasing the pressure drop and reducing oil production. In this work the three dimensional, transient, turbulent, biphasic problem is solved by combining the Dense Discrete Phase Model (DDPM) and Discrete Element Method (DEM), to analyze the influence of certain parameters on the particle deposition, which represents the calcium carbonate scale formation, inside the wall of a horizontal pipeline at well conditions. The obtained results show that particle deposition is higher at lower Reynolds numbers. The results also show that the use of DEM model is more representative, but due to the high computational effort required, it application in complex geometries must be carefully evaluated.

Due to the concern about oil's extraction efficiency decline throughout the time, researchers have looked for alternatives to raise the displacement efficiency of trapped oil within micropores, which has a known complex geometry. The use of numerical simulation presents advantages since it is an economically viable technology with good precision. The current proposition analyzes numerically and with the aid of the Ansys Fluent software, the influence of wettability in microcavity geometry in the displacement of oil by water. Several cases with different radius curvatures of the geometry, contact angles and their influence in displacement efficiency of residual oil are evaluated. The results led to a more realistic analysis regarding the mobilization of trapped oil within the microcavities.

Surfactant flooding consists of the injection of a chemical added to water to reduce the interfacial tension of oil/water and alter the wettability of reservoir rock, producing larger quantities of residual oil. The aim of this study is to verify the sensitivity of oil recovery factor and oil breakthrough time to surfactants flooding parameters, such as surfactant concentration, initial water saturation, oil viscosity and injection rate. For this, we used the UTCHEM software, seeking to obtain a sensitivity analysis of these variables. Oil breakthrough time is the time at which the oil-water bank arrives at the producing well. From the obtained results it is noticed that for a lower initial water saturation, a higher recovery factor is generated. It has been demonstrated the existence of a critical water saturation, from which the oil breakthrough time begins to increase.

Steam injection is one of the more common techniques between thermal methods for heavy oil recovery. An injection pipe is used to transport the steam generated at the surface to the petroleum reservoir. The challenge in this process is minimize the heat transfer to the surroundings of the injector well. This work presents the three-dimensional simulation of the multiphase turbulent liquid-vapor flow along the wellbore domain composed by injection pipe, annular space, casing and formation. The response of the tubing insulation and formation temperature to steam injection at 80% of quality, injected at two different flow rates, is investigated with Ansys CFX software. It is clear the better performance of VIT (vacuum insulated tubing) technology. In addition, as greater the flow rate is, the higher the steam quality results. Finally, is proposed the existence of a critical tubing conductivity below which an opposite behavior of the quality is observed: low steam flow rate allows a high steam quality.

Oil recovery by water injection is a common method in petroleum industry. Although the macroscopic point of view monitoring the sweep efficiency is the usual approach, several phenomena could studied more effectively at the microscale. Capillary and viscous forces, together with geometry arrange of the medium, are responsible by the mobilization and trapping the oil. With the goal of studying the dynamic of the microscopic process and the influence of discretization algorithms, boundary condition, and time step, in this work it is used the software Ansys Fluent, with volume of fluid technique, to simulate the two-phase, transient, Newtonian and laminar flow. The 2D Cartesian domain is a system with circular constrictions representing a simplified porous media initially fully filled with oil where the periodic boundary condition is applied. At the microscale, oil films are retained around the grains walls and recirculation acts trapping the oil. This volume is slowly removed result of the continuous water injection. Two stages are well identified in this process. One with linear decrease whit time, which is in according with our analytical prediction until the water breakthrough, followed by the stabilization where the continue water injection has no effect in the oil displacement. Consequently, the oil recovery is not complete, a fraction of it will remains in the porous medium. In addition, it is possible to identify the numerical algorithms for this microscale immiscible liquid/liquid displacement problem, which presents the more coherent physical results.

In this work, water is injected to displace oil from a micro square cavity. Fluids are incompressible, Newtonian and immiscible. The governing equations of the two-phase, transient, laminar, isothermal flow problem are solved numerically using Ansys Fluent software coupled with volume of fluid technique and appropriated numerical parameters. The qualitative and quantitative results are obtained following the volumetric oil fraction along the spatial domain and time. The methodology proposed allows a correct description of the oil displacement process, demonstrating its complexity and dependence of physical parameters. Oil recovery factor is higher when interfacial tension is low and water is the wetting fluid.

Computational tools for simulation of multiphase flow in oil pipelines are of great importance for the determination of the technical feasibility of the production in oilfields. The present article presents the mathematical and numerical modeling of the oil biphasic flow in a partially submerged onshore pipeline. The biphasic behavior of the heavy oil of 13,2ºAPI is translated by the Dukler correlation. The oil’s viscosity is regarded as dependent on the temperature and on the API density of the oil by means of the Hossain correlation. The pipeline, of 3,600m and 4 inches (10.16cm) in diameter, transports the oil from a collecting station to a storage center and consists of three sections. The first and third sections are above ground and are in contact with the external environment. The intermediate section is sitting on the river bed and is the critical part of the pipeline, once high heat losses are observed. The influence on the type of pipe insulation in the pressure and temperature gradients was analyzed with the aid of commercial 1D software Pipesim®. The results, of this 1D and non-isothermal problem with prescribed outlet pressure, show that the use of isolation when appropriately designed in terms of material quality and thickness is of utmost importance to maintain the heat transfer at low levels, in order to ensure the movement of fluids in long sections without compromising the system operation.

One of the most important tasks in Petroleum Engineering is a reservoir characterization. A good knowledge of the properties of the reservoirs is essential for reliable production forecasts and the application of special methods of secondary recovery. A very useful tool for this purpose is the numerical simulation of oil reservoirs, which through the application of numerical methods allows for the solution of complex differential equations by nature. This paper deals with the computational modeling of foam injection in oil reservoirs using the Eclipse (R) software. The main objective of this research is to understand what the parameters that maximize the increase of the oil recovery factor retained in the pore space after using conventional methods are. Foam is injected from the surface into a reservoir of 8.400 feet deep containing oil viscosity which is dependent on the pressure, this oil is conducted to the surface through a production well. Both wells are completed over the entire thickness of the formation of interest. Equations that express the detailed model and the foam are discretized together with the governing equations of the fluid flow. Comparisons at different foam concentration are shown for light, intermediate and heavy oils. Results show that there is a direct correlation between the concentration of the displacing fluid foam and the oil recovery factor. Note also that a critical concentration c* foam is evidenced with direct influence on the efficiency of the process. (C) 2013 CIMNE (Universitat Politecnica de Catalunya). Published by Elsevier Espana, S.L.U. All rights reserved.

The sucker rod pump is an artificial lift method frequently applied in onshore petroleum wells. This system can be described using a numerical simulation based on the behavior of a rod string. In the past, the elastic behavior of the rod string made it difficult to model the system. However, since the 1960s and with the advent of digital computers, it has been modeled numerically. The rod string behaves like a slender bar, and thus, the propagation of elastic waves along the bar can be represented by a one-dimensional equation. Gibbs (1963) presented a mathematical model based on the wave equation, which is described on the basis of the analysis of forces on the rod string and is incorporated into a boundary value problem involving partial differential equations. The use of the finite difference method allows for a numerical solution by the discretization of the wave equation developed in the mathematical formulation with appropriate boundary and initial conditions. This work presents a methodology for implementing an academic computer code that allows simulation of the upstroke and downstroke motion of the rod string described by the wave equation under ideal operating conditions, assuming a harmonic motion of the rod at one end and downhole pump at the other end. The goal of this study is to generate the downhole dynamometer card, an important and consolidated tool that controls the pump system by diagnosing operational conditions of the downhole pump.

Oil and gas can be found inside porous rocks or reservoirs. The path of the fluid flow is subjected to tortuosities, obstructions and abrupt changes in direction. This often happens in a micro-scale, whereby competition between capillary and viscous forces mainly governs the fluid flow. In order to increase the recovery factor or sustain the reservoir pressure, one common procedure is to pump gas or water through an injector well. Hydrocarbons can then be displaced to the bottom of the producer well and then pumped in pipelines to surface facilities, where they can be collected and processed. Because the main objective of any recovery process is to minimize the amount of oil remaining in the rock, it is important to know how geometry, fluid properties and operational conditions affect the process. In this work, transient gas-liquid displacement of a Newtonian liquid inside channels with sinusoidal obstructions is analyzed numerically. The influence of the degree and number of constrictions in the thickness of the liquid film is determined at different process conditions by solving the transient, two-dimensional, viscous free surface liquid flow in the channel. The shape of the interface needs to be determined as part of the solution. The system of equations, with appropriate boundary conditions, was solved with the Galerkin finite element method and implicit time integration. Preliminary results show the bubble evolution and the influence in the pressure and tip velocity.

Slot coating is a common method in the manufacture of a wide variety of products. It belongs to a class of coating method known as premetered coating: in a steady-state operation, the thickness of the coated liquid layer is set by the flow rate fed to the die and the speed of the substrate moving past, and is independent of other process variables. Thus premetered methods are ideal for high precision coating. However, even the best designed slot coating operations are subjected to small oscillations on the process conditions, such as flow rate, vacuum pressure and gap fluctuations. These oscillation may lead to unacceptable variation on the thickness of the deposited liquid layer. The effect of process condition disturbances on the coated layer has to be minimized to assure a wet thickness as uniform as possible. The effect of an imposed periodic perturbation on the liquid flow rate or on the gap clearance in the coated layer thickness is explored in this work by computer-aided analysis. The amplitude of the thickness variation is determined at different process conditions and die configurations by solving the transient, two-dimensional, viscous free surface liquid flow in the coating bead. The system of equations, with appropriate boundary conditions, was solved by the Galerkin/finite element method, and an implicit time integration. The results show the response as a function of the imposed perturbation frequency and of the die geometry. They indicate that the die geometry may be optimized in order to minimize the film thickness oscillation of a slot coating operation. (C) 2008 Elsevier Ltd. All rights reserved.

Coating die edges are not mathematical corners, they are rounded. Contact lines do not actually pin. The effects of the radius of curvature of the downstream edge of slot dies on contact line location, effective contact angle, and low-flow limit—air-fingers penetrating from downstream and breaking apart the coating-bead—are examined by solving the Navier-Stokes system for Newtonian flow. The geometry of the die surface is represented by two straight lines and an arc of circle connecting them. The local contact angle is treated as a specified equilibrium value. The system of equations is solved by Galerkin's method and finite element basis functions. The results show how the edge rounding affects the contact line position and stability of the flow, and indicate the minimum radius of curvature necessary to apparently pin the contact line. © 2005 American Institute of Chemical Engineers AIChE J, 2006

The region of acceptable quality in the space of operating parameters of a coating process is usually bounded by various coating defects. An important limit of the slot coating process is the low-flow limit. It is the maximum web speed at a given film thickness and distance between coating die and web (coating gap); equivalently, the minimum film thickness at a given web speed and coating gap; again equivalently, the maximum gap at a given film thickness and web speed at which the coating bead remains stable. The condition that defines this limit is a force balance at the downstream meniscus of the coating bead, where the coated layer is carried away by the web translating past the die. Although most of the liquids coated industrially are polymeric solutions, dispersions, or both, that are not Newtonian, most previous investigations of the low-flow limit in slot coating dealt with Newtonian liquids. Recently, the effect of high molecular weight polymer on the low-flow limit of slot coating was examined by visualization experiments and theoretical analysis using an algebraic non-Newtonian model that takes into account the extensional thickening behavior of polymer solutions. Although Generalized Newtonian Models of this class may capture the different ways that dilute polymer molecules behave in extension- and shear-dominated flow zones and the reported predictions display the same trends that are observed experimentally, algebraic models cannot represent viscoelastic stresses. In the present work, the low-flow limit of slot coating of mildly viscoelastic liquids is examined by solving the conservation equations for two-dimensional flow, coupled with either of two differential viscoelastic models that describe the mechanical behavior of dilute polymer solutions (namely the Oldroyd-B and FENE-CR models). The results show how the different rheological properties affect the flow and the critical conditions at the onset of the low-flow limit.

Slot coating is a common method in the manufacture of a wide variety of products. It belongs to a class of coating method known as premetered coating: the thickness of the coated liquid layer in principle is set by the flow rate fed to the die and the speed of the substrate moving past, and is independent of other process variables. Thus, premetered methods are ideal for high precision coating. An important operating limit of slot coating is the minimum thickness that can be coated at a given substrate speed, generally referred to as the low-flow limit. The mechanism that defines this limit balances the viscous, capillary and inertial forces in the flow. Although most of the liquids coated industrially are polymeric solutions and dispersions that are not Newtonian, previous analyses of the low-flow limit in slot coating dealt only with Newtonian liquids. In this paper, the low-flow limit in slot coating of an extensional thickening polymer solution is examined both by theory and by experiment. The continuity and momentum equations coupled with an algebraic non-Newtonian constitutive equation that relates stress to the rate-of-strain and relative-rate-of-rotation tensors were solved by the Galerkin/finite element method to model the flows. The flows themselves were visualized by video microscopy and the low-flow limit was found by observing, at given substrate speed, the feed rate at which the flow becomes unstable and breaks up. Various solutions of low molecular weight polyethylene glycol (PEG) and high molecular weight polyethylene oxide (PEO) in water were used in order to evaluate the effect of mildly viscoelastic behavior on the process. At the concentration level of the high molecular weight polymer explored here, the viscoelastic behavior of the solutions could not be accessed by oscillatory tests; the only measurable response to the addition of PEO was the rise of the apparent extensional viscosity.