Influence of the polymer properties and numerical schemes on tertiary oil recovery processes

Chemical Enhanced Oil Recovery (EOR) processes comprise a number of flooding techniques aimed at increasing the operational life of mature oilfields. Among these, polymer flooding is one of the most developed; its functionality is to increment the aqueous viscosity, avoiding the formation of viscous fingering. Reservoir simulators consider this influence as well as other physical properties (e.g., adsorption, permeability reduction). However, the polymer degradation is usually not considered even though it plays a critical role in the viscosity. In this paper this mechanism is analyzed and coupled with the previously mentioned physical phenomena in order to present a complete study of their influence in the EOR process. Moreover, since a fully second-order accuracy scheme is used along with a Total Variation Diminishing (TVD) flux-limiting function, the influence of the latter on the recovery factor is also discussed. Results showed that the negative effect of the polymer adsorption was the most relevant physical phenomenon in terms of the oil recovery. Furthermore, the analysis of the discretization of the differential equations showed that traditional, linear first-order schemes created numerical diffusion affecting negatively the macroscopic sweeping efficiency, which disappeared when TVD techniques were used. Reservoir simulators allow determining the desired designing properties for future polymers in relationship with the characteristics of the oilfield to be exploited

Influence of the polymer degradation on enhanced oil recovery processes

Polymer flooding is one of the most common and technically developed chemical Enhanced Oil Recovery (EOR) processes. Its main function is to increase the carrying phase's (i.e., water or brine) viscosity in order to mobilize the remaining trapped oil. Many numerical simulators have been developed during the last 30 years considering the influence of the polymer molecules on the viscosity as well as on other physical parameters (e.g., diffusion, adsorption). Nevertheless, there are certain phenomena which were not previously considered, for instance, the interfacial effects of hydrophobically modified polymers. Furthermore, the degradation of the polymer molecules in a harsh environment such as the one found in porous media is well known. This causes a deterioration on the viscosifying properties, diminishing the efficiency of the method. It is important also to consider the effect of the polymer viscoelasticity on the microscopic sweeping efficiency, lowering the residual oil saturation, which has not been properly addressed. A new compositional 2D numerical simulator is presented for polymer flooding in a two-phase, three-component configuration, considering all these physical effects present in porous media and using a fully second-order accurate scheme coupled with total variation diminishing (TVD) functions. Results demonstrated that degradation cannot be considered negligible in any polymer EOR process, since it affected the viscoelastic and viscosifying properties, decreasing the sweeping efficiency at both micro- and macroscopic scales. This simulator will allow setting the desired designing properties for future polymers in relationship with the characteristics of the oil field to be exploited

Branched polymers and nanoparticles flooding as separate processes for enhanced oil recovery

Since it was first theorized more than half-century ago, nanotechnology has proven to be the perfect boost for existing technologies and the oil industry has made use of this avant-garde discipline to upsurge the productivity of mature oilfields. With respect to polymer flooding, recent research has stressed the importance of the (macro) molecules' architecture on the physical properties. This paper presents the numerical simulation of these two agents in standard, not combined, oil recovery processes. The polymer solution viscosity is calculated considering the polymer's architecture, its degradation and the salinity. The nanoparticles affect the carrier-phase viscosity and the rock formation wettability, which modifies the oil mobility. Results evidenced the improved capabilities of branched (i.e. star/comb) polymers with respect to traditional linear ones. The modified architecture improves not only the rheological but also the viscoelastic properties, which ultimately increases the microscopic sweeping efficiency. Nanoparticles increase slightly the carrier phase viscosity, but their main recovery mechanism is their adsorption onto the rock and subsequent wettability modification, reducing the residual oil saturation. Furthermore, it is also important to properly characterize both the particles' average size and also their aggregation rate, since these affect the recovery efficiency. Simulations show the importance of a good characterization of oil recovery agents and their effect on the phases' physical properties as well as the potential of nanoparticles to act as a boost of traditional enhanced recovery processes

Chemical enhanced oil recovery and the role of chemical product design

The current and prospective worldwide energy demands have led either to start exploiting the more difficult and costly unconventional oil reserves, or to maximize the exploitation of conventional oil sources. This triggered the development of enhanced oil recovery processes in order to improve the efficiency and lifetime of mature oilfields. Chemical Enhanced Oil Recovery is one of the most interesting group of methods nowadays. The use of chemical products such as polymers, surfactants, alkalis and polymeric surfactants has been continuously increasing during the last decades. However, these chemicals should be designed to withstand the harsh conditions present in the reservoir (e.g., dissolved salts, pH, temperature, presence of bacteria) and increase the efficiency of the process. One of the key factors in this development is the (macro)molecules’ architecture and its influence on the physical properties of the fluids being injected: from linear to branched polymers, from monomeric to gemini surfactants. Furthermore, the combination of these chemicals has showed a great potential due to the synergy between them, creating a new spectrum of techniques in chemical Enhanced Oil Recovery. This review presents the work done in this field with an analysis of the products and technologies employed, including their limitations and possible ways to improve their performance. All in all, the need of advanced products for oil recovery and new, or improved, energy sources has set off a new field of research wherein chemical product engineering plays a major role

120kev Ar8+-li Collisions Studied By Near Uv And Visible Photon Spectroscopy

A spectroscopic analysis of light emitted in the 200-600 nm wavelength range by Ar7+, Ar6+ and Ar5+ ions after charge exchange in 120keV Ar8+-Li collisions is performed. Transitions with Δn = 1 and Δn = 2 for n = 8, 9, 10 and 11 states of Ar8 following single electron capture are identified and the production cross sections for n = 8 and n = 9 are deduced from emission cross sections and compared with those calculated by the three-body classical trajectory Monte-Carlo method. Lines due to double capture process were observed and identified as Rydberg transitions 3snl-3sn\u27l\u27 (n = 7, 8 and 9) in Ar VII. Lines due to triple electron capture process were found and identified as transitions 3s2nl-3s2n\u27ï and 3s3pnl- 3s3pril\u27(n = 7, 8) in Ar VI. The configurations produced during the collision provides evidence that electron-electron interaction play an important role in double and triple charge exchange processes. © 1993 IOP Publishing Ltd

THE SOCIO-POLITICAL IMPACT OF DEAF LEADERS' DISCOURSE IN ARGENTINA

Actualmente, la Argentina es el escenario del impacto sociopolítico del discurso político de los líderes Sordos. Desde los 90, en el medio de una de las más dramáticas crisis económicas, los excluidos luchan por encontrar nuevas identidades, y así el discurso político Sordo (DPS) emerge. El discurso de las ciencias sociales y sus prácticas llevan a la legitimación de la Lengua de Señas Argentina (LSA) y los lingüistas funcionamos como investigadores orgánicos. Las personas Sordas empiezan a convertirse en letrados a través del uso de las nuevas tecnologías y fuera de la escuela formal. El propósito de este trabajo es analizar la jerarquización de la información desde la Lingüística Funcional y el Análisis del Discurso en un corpus recolectado en el 2007. El análisis de los temas y los remas mostrará los objetivos y los contenidos que el DPS tira en la arena de la lucha sociopolítica. Hipotetizamos la existencia del Tema del Evento y Rema del Evento que pertenecen a la práctica discursiva que actúa dialécticamente –en términos lacanianos– con la práctica social. Estos dos discursos, líderes Sordos y lingüística, generan una tensión intertextual que intenta fragmentar al discurso dominante.Currently, Argentina is the scenario of the socio-political impact of the discourse of Deaf leaders. Since the 90’s, in the middle of the most dramatic economic crisis, the excluded fought to find new identities and the Deaf political discourse or DPD emerges. The social sciences discourse and its practices produced the legitimation of Argentine Sign Language (LSA) and we the linguists function as organic researchers. Deaf people start to become literate through the use of new technologies and outside formal school. The purpose of this paper is to analyze the information distribution through Functional Linguistics and Discourse Analysis in a corpus gathered in the year 2007. The analysis of theme and rheme will show the aims and subjects DPD threw into the arena of socio-political fight. We further hypothesize the existence of Event Theme and Event Rheme which clearly belong to a discursive practice that acts dialectically –in Lacan’s terms– in order to change social practice. These two discourses  –Deaf leaders and linguistics- intend to generate an intertext tension which is fragmenting dominant discourse

VIII Encuentro de Docentes e Investigadores en Historia del Diseño, la Arquitectura y la Ciudad

Acta de congresoLa conmemoración de los cien años de la Reforma Universitaria de 1918 se presentó como una ocasión propicia para debatir el rol de la historia, la teoría y la crítica en la formación y en la práctica profesional de diseñadores, arquitectos y urbanistas. En ese marco el VIII Encuentro de Docentes e Investigadores en Historia del Diseño, la Arquitectura y la Ciudad constituyó un espacio de intercambio y reflexión cuya realización ha sido posible gracias a la colaboración entre Facultades de Arquitectura, Urbanismo y Diseño de la Universidad Nacional y la Facultad de Arquitectura de la Universidad Católica de Córdoba, contando además con la activa participación de mayoría de las Facultades, Centros e Institutos de Historia de la Arquitectura del país y la región. Orientado en su convocatoria tanto a docentes como a estudiantes de Arquitectura y Diseño Industrial de todos los niveles de la FAUD-UNC promovió el debate de ideas a partir de experiencias concretas en instancias tales como mesas temáticas de carácter interdisciplinario, que adoptaron la modalidad de presentación de ponencias, entre otras actividades. En el ámbito de VIII Encuentro, desarrollado en la sede Ciudad Universitaria de Córdoba, se desplegaron numerosas posiciones sobre la enseñanza, la investigación y la formación en historia, teoría y crítica del diseño, la arquitectura y la ciudad; sumándose el aporte realizado a través de sus respectivas conferencias de Ana Clarisa Agüero, Bibiana Cicutti, Fernando Aliata y Alberto Petrina. El conjunto de ponencias que se publican en este Repositorio de la UNC son el resultado de dos intensas jornadas de exposiciones, cuyos contenidos han posibilitado actualizar viejos dilemas y promover nuevos debates. El evento recibió el apoyo de las autoridades de la FAUD-UNC, en especial de la Secretaría de Investigación y de la Biblioteca de nuestra casa, como así también de la Facultad de Arquitectura de la UCC; va para todos ellos un especial agradecimiento

Polymer and nanoparticles flooding as a new method for Enhanced Oil Recovery

A new Enhanced Oil Recovery (EOR) method is proposed by combining the effects of a traditional polymer flooding and exploiting the advantages that nanotechnology presents in the oil industry. Thus, a novel technique is introduced and applied to a 2D reservoir model with a two-phase, five-component system (aqueous, oil phases and water, hydrocarbon, polymer, nanoparticles and salt). For the polymer characterization, a novel approach is presented considering the polymer's architecture and its degradation in order to calculate the physical properties, which has never been reported in reservoir simulation. The presence of the nanoparticles affects mainly the rheological behavior and the wett ability of the rock, increasing the oil phase mobility. Moreover, negative effects such as particle aggregation and sedimentation are also modeled using a novel formulation in reservoir simulation. The combined action of polymers and nanoparticles allowed increasing the recovery factors beyond standard EOR processes, and it represents a suitable alternative to replace traditional combined methods, such as Surfactant-Polymer (SP) or Alkaline-Surfactant-Polymer (ASP). This is due to the fact that the nanoparticles act, to a greater or lesser extent, on the wettability, rheological and interfacial properties of fluids and rock formation, which is complemented with the polymer's viscosifying properties. Moreover, economical factors could also render this technique more attractive, since the nanoparticles' associated costs are substantially lower than those from surfactant flooding. This simulation proves the potential of nanotechnology as a mean to boost traditional EOR techniques in order to further increase the operative life of mature oil fields

Numerical modeling of a compositional flow for chemical EOR and its stability analysis

A new two-dimensional surfactant flooding simulator for a three-component (water, petroleum, chemical), two-phase (aqueous, oleous) system in porous media is developed and analyzed. The compositional physical model is governed by a system of non-linear partial differential equations composed of Darcy's and mass conservation equations. The system is then numerically solved by a finite difference method using the IMPEC (IMplicit Pressure and Explicit Concentration) scheme. Physical properties are described by a set of concentration-dependent algebraic equations. Additionally, a novel numerical stability analysis is presented in order to study the robustness of the new simulator. The oil recovery factor showed a strong dependency on the surfactant properties and phase behavior, which should be carefully evaluated. In order to achieve this, the new simulator utilizes and modifies a simplified ternary diagram to model accurately the component partitioning. Results showed that surfactant partitioning is the most relevant parameter in the recovery process. Numerically speaking, the simulator behaved according to the results obtained in the matrix stability analysis. Using the non-iterative IMPEC, a critical time value was found beyond which the system yielded large oscillatory values for the produced flowrates. The simulator can be employed to design and optimize chemicals used in enhanced oil recovery (EOR) processes before field application. (C) 2017 Elsevier Inc. All rights reserved