[pt] Os testes de formação são uma operação realizada com o objetivo de identificar os fluidos, determinar os parâmetros de reservatório associados à produtividade e avaliar a extensão da jazida. Para executar o teste, o poço é completado temporariamente para permitir a produção dos fluidos de forma segura, e o intervalo a ser testado é isolado e um diferencial de pressão entre a formação e o interior do poço é estabelecido, forçando os fluidos da formação a serem produzidos. A busca por uma forma de substituir os testes de produção tradicionais, evitando a queima de gás natural e o aumento da segurança operacional, somada ao fato de completações de poços injetores de água na zona produtora de óleo ser uma prática comum do desenvolvimento de campos marítimos, levaram os testes de injetividade a ter um importante papel no gerenciamento dos reservatórios desses campos. Embora os métodos de análise de fluxo monofásico com pequena compressibilidade sejam bem documentados na literatura, soluções bifásicas e métodos de análise ainda precisam ser desenvolvidos. Nessa dissertação, é proposta a modelagem do problema de testes de injetividade com vazão variável, utilizando soluções analíticas aproximadas. / [en] The pressure response during a well test provides information on well productivity and reservoir performance. To replace traditional production tests, avoiding the gas flaring and increasing operational safety, the injectivity test began to play an important role in the management of the reservoirs in these fields. Although analytical models are able to describe injection and falloff periods, variable rate models still need to be developed. This work attempts to present a variable rate approximate solution for pressure response in a water injection well. The accuracy of the proposed solution was assessed by comparison with a numerical simulator. The suggested model was also used to determine the reservoir equivalent permeability.

Master of Science / Department of Geology / Matthew Totten / The Petersilie oil field in Ness County, Kansas produces out of the Mississippian System, a reservoir composed mainly of shallow water carbonates, at depths of around 4375 ft (1334 m). The lithology of the field ranges from limestone to dolomite, to interlaminated limestone-dolomite beds. Chert is commonly found throughout. Petersilie field lies to the west of the Central Kansas Uplift, and to the east of the Hugoton Embayment. The field saw much drilling activity in the 1960’s, when it reached a production peak of nearly 378,000 barrels of oil per year. Production declined swiftly after that until the late 1990’s, when waterflooding was successfully employed. In this study, a reservoir model was produced for the Mississippian as it occurs in Petersilie field using the Department of Energy’s EdBOAST reservoir modeling software, with the intent of providing a reference for future drilling activity in the Mississippian and determining reservoir characteristics that may have contributed to the effectiveness of waterflooding in this area. The reservoir model was checked by simulation with a companion reservoir simulator program, BOAST 98. Subsequent comparison of simulated and actual oil production curves demonstrates the reliability of well log and drill stem test data for the field and proves the reservoir model to be a good fit for the Mississippian in Petersilie. Production curve analysis of Petersilie indicates the field was an ideal candidate for waterflooding because it has a solution-gas drive mechanism. As the field approached depletion from primary recovery, oil saturations remained high. Petersilie also exhibits high porosity and good permeability. The BOAST software was found to be an effective and inexpensive means for understanding the Mississippian reservoir in central to south-central Kansas. It was determined that BOAST has potential for practical use by smaller independent oil companies targeting the Mississippian in Kansas.

Experiments involving the dissociation of artificial methane-hydrate-bearing sediments were performed using X-ray computed tomography (X-CT, 40 s scanning speed at 2 min intervals) to directly observe dissociation behavior in the sediments and the gas and water flows generated by dissociation. Dissociation by depressurization was performed using a backpressure regulator, and showed that the temperature reduction induced by depressurization depends on the phase equilibrium state of methane hydrate, and that preferential dissociation occurs along the periphery of the core. This behavior is caused by heat flux from the outside of the core, and this controls the dissociation rate. A heat exchanger was installed at one end of the core to simulate thermal stimulation, and propagation of a clear and unidirectional dissociation front was observed. Depending on the heating temperature, the dissociation rate was less than that observed for depressurization. Hot water was also injected at a constant rate from the bottom of the core, and CT images showed the movement of distinct accumulations of dissociated gas being pushed by the hot water. The gas production rate increased immediately after the gas accumulation reached the opposite end of the core where the gas and water flow out.

Hot water injection is a production technique proposed to gas recovery from methane hydrate reservoirs. However, from a practical point of view, the injected water experiences a drop in temperature and re-formation of hydrates may occur in the reservoir. In this work, we proposed a model expressing permeability hysteresis in the processes between hydrate growth and dissociation, and studied hydrate dissociation behavior during hot water injection. The model of permeability hysteresis was incorporated into the simulator MH21-HYDRES (MH21 Hydrate Reservoir Simulator), where the decrease in permeability with hydrate saturation during hydrate growth process was assumed to be much larger than the decrease during hydrate dissociation process. Laboratory hydrate dissociation experiments were carried out for comparison. In each experiment, we injected hot water at a constant rate into a sand-packed core bearing hydrates, and the histories of injection pressure, core temperature, and gas/water production rates were measured. Numerical simulations for the core experiments showed the re-formation of hydrates led to the increase in injection pressure during hot water injection. The simulated tendencies of pressure increase varied markedly by considering permeability hysteresis. Since the experimental pressure increases could not be reproduced without the permeability hysteresis model, the influence of permeability hysteresis should be considered to apply hot water injection to hydrate reservoirs.

[pt] A eficiência do processo de injeção de água, o método de recuperação secundária mais comum na indústria do petróleo, é limitada por seu padrão de varredura não uniforme, originado da formação de caminhos preferenciais devido à alta razão de mobilidade entre água e óleo, e a elevada saturação de óleo residual, associada aos efeitos capilares. A fim de melhorar a recuperação de petróleo, diferentes abordagens têm sido sugeridas na literatura, com algumas delas baseadas no bloqueio de poros e consequente desvio de água, varrendo assim uma área maior do reservatório e deslocando mais do óleo aprisionado por capilaridade. O bloqueio de poros pode ser realizado com diferentes métodos, sendo um deles a injeção de emulsão, com a fase dispersa, composta por gotas de óleo, atuando como o agente responsável pela diminuição da mobilidade da fase aquosa. Neste trabalho, os mecanismos fundamentais do processo de injeção de emulsão foram estudados experimentalmente, visualizando-se o escoamento em escala de poros em um dispositivo micro-fluídico de vidro composto por uma rede de canais constritos, que modela as principais características de um meio poroso. Os resultados mostram o efeito do tamanho da gota e do número de capilaridade no padrão do escoamento, no tamanho dos gânglios do óleo aprisionado e na recuperação de óleo residual. / [en] The efficiency of water flooding, the most common secondary recovery method in the oil industry, is limited by its non-uniform sweep pattern, originating from the formation of preferential paths because of the high mobility ratio between water and oil, and the high residual oil saturation, associated with capillary oil trapping. In order to improve oil recovery, different approaches have been suggested in the literature, with some of them based on pore blocking and consequent water diversion, thus sweeping a bigger area of the reservoir and displacing more of the trapped oil. Pore blockage can be performed with different methods, one of which is emulsion flooding, with the disperse phase, composed by oil drops, acting as the agent responsible for the decreased water phase mobility. In this work, the fundamental mechanisms of emulsion flooding process was studied experimentally, by visualizing the pore-scale flow in a glass microfluidic device composed of a network of constricted channels, that models the main features of a porous media. The results show the effect of drop size and capillary number on the flow pattern, trapped oil ganglia size and residual oil recovery.

Orientador: Denis Jose Schiozer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-12T08:32:24Z (GMT). No. of bitstreams: 1 MontoyaMoreno_JuanManuel_M.pdf: 2098742 bytes, checksum: c03cbaf7c1d95c189a074da09d33d7dd (MD5) Previous issue date: 2007 / Resumo: A injeção de água tem sido um método de recuperação de petróleo muito usado na industria do petróleo. Um dos principais problemas associados a este método e a perda da injetividade. Diferentes procedimentos tem sido propostos para minimizar os efeitos de tal perda, um dos quais e a injeção acima da pressão de fratura, que consiste em injetar água com pressão suficiente para criar canais de alta condutividade, com o objetivo de restaurar a injetividade inicial do poço. Este procedimento tem se mostrado viável, tendo como vantagem à manutenção da injetividade em valores similares aos iniciais, embora apresente dificuldade de modelagem e incertezas em relação à eficiência de varrido, ao comportamento da frente de avanço da fratura e a influencia desta na recirculação da água. Uma forma adequada de modelar esse fenômeno e a integração da geomecanica com a simulação de escoamento, mas este tipo de abordagem envolve maior custo computacional, alem de não ter sido completamente implementado em aplicações comerciais, o que dificulta aplicações praticas. Outras diferentes técnicas de simulação são usadas para modelar o fenômeno, tais como modificadores de transmissibilidade associados a refinamentos locais de malha. Neste trabalho, e proposta a simulação da fratura por meio do uso de um poço horizontal virtual, usando um simulador comercial de escoamento e um software para simulações de processos de faturamento hidráulico acoplados explicitamente. De inicio, modela-se a perda de injetividade num poço injetor de água e, junto com o modelo geomecanica de fratura, usam-se modificadores de transmissibilidade para modelar a fratura como modelo de referencia. Posteriormente, introduz-se um modelo de fratura representado por um poço horizontal virtual mediante programação em simuladores comerciais. Os resultados mostram que o poço horizontal virtual representa adequadamente o comportamento da fratura em relação ao modelo de modificadores de transmissibilidade, evitando necessidade de refinamentos locais, tornando-se uma ferramenta útil para simular casos de campo em grande escala. Palavras-Chave: simulação de reservatório; injeção de água; perda de injetividade; injeção de água acima da pressão de fratura; geomecanica. / Abstract: Water injection has been the most used method to improve oil recovery. The main problem of this method, related directly with operational efficiency, is the injectivity loss which is the loss of capacity to maintain water injection rates due to formation damage. Different models have been proposed to minimize the injectivity loss effects due to its high economic impact on oil production. One of these methods is water injection above formation parting pressure. It consists in creating high conductivity channels inside the reservoir to restore or to increase well injectivity. This method has advantages associated with injectivity maintenance but it is difficult to model and it presents uncertainties in relation to sweep efficiency, to fracture tip behavior and its influence on the water re-circulation. One way to model the problem is the integration of geomechanical and flow simulation, but it requires a higher computation time and it has not been completely implemented in commercial simulators. Different techniques are used to model the water injection above formation parting pressure, such as transmissibility modifiers associated with local grid refinement. In this work, a methodology is proposed for fracture simulation using both numerical fluid flow and geomechanical simulators, coupled explicitly, using a virtual well to model the fracture. Initially, injectivity loss is modeled and, along with geomechanical fracture model, transmissibility modifiers are used to model the fracture. This model represents the reference fracture model. Then, the fracture is represented by a virtual horizontal well, allowing easy implementation into commercial simulators. The results show that the virtual horizontal well represents adequately the fracture's behavior given by the reference model, avoiding local grid refinement and, allowing full field scale simulations without simulation grid modification. / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

The low salinity water injection technique (LSWI) has become one of the important research topics in the oil industry because of its possible advantages for improving oil recovery. Several mechanisms describing the LSWI process have been suggested in the literature; however, there is no consensus on a single main mechanism for the low salinity effect on oil recovery. As a result of the latter, there are few models for LSWI and especially for carbonates due to their heterogeneity and complexity. In this research, we proposed a systematic approach for modeling the LSWI effect on oil recovery from carbonates by proposing six different methods for history matching and three different LSWI models for the UTCHEM simulator, empirical, fundamental, and mechanistic LSWI models. The empirical LSWI model uses contact angle measurements and injected water salinity. The fundamental LSWI model captures the effect of LSWI through the trapping number. In the mechanistic LSWI model, we include the effect of different geochemical reactions through Gibbs free energy. Moreover, field-scale predictions of LSWI were performed and followed by a sensitivity analysis for the most influential design parameters using design of experiment (DoE). The LSWI technique was also optimized using the response surface methodology (RSM) where a response surface was built. Also, we moved a step further by investigating the combined effect of injecting low salinity water and carbon dioxide on oil recovery from carbonates through modeling of the process and numerical simulations using the UTCOMP simulator. The analysis showed that CO₂ is the main controller of the residual oil saturation whereas the low salinity water boosts the oil production rate by increasing the oil relative permeability through wettability alteration towards a more water-wet state. In addition, geochemical modeling of LSWI only and the combined effect of LSWI and CO₂ were performed using both UTCHEM and PHREEQC upon which the geochemical model in UTCHEM was modified and validated against PHREEQC. Based on the geochemical interpretation of the LSWI technique, we believe that wettability alteration is the main contributor to the LSWI effect on oil recovery from carbonates by anhydrite dissolution and surface charge change through pH exceeding the point of zero charge. / text

Made available in DSpace on 2014-12-17T14:08:32Z (GMT). No. of bitstreams: 1 JoseTMAP.pdf: 3429155 bytes, checksum: 9d06d453f156a78546476b9e1a22c995 (MD5) Previous issue date: 2008-12-15 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Until the early 90s, the simulation of fluid flow in oil reservoir basically used the numerical technique of finite differences. Since then, there was a big development in simulation technology based on streamlines, so that nowadays it is being used in several cases and it can represent the physical mechanisms that influence the fluid flow, such as compressibility, capillarity and gravitational segregation. Streamline-based flow simulation is a tool that can help enough in waterflood project management, because it provides important information not available through traditional simulation of finite differences and shows, in a direct way, the influence between injector well and producer well. This work presents the application of a methodology published in literature for optimizing water injection projects in modeling of a Brazilian Potiguar Basin reservoir that has a large number of wells. This methodology considers changes of injection well rates over time, based on information available through streamline simulation. This methodology reduces injection rates in wells of lower efficiency and increases injection rates in more efficient wells. In the proposed model, the methodology was effective. The optimized alternatives presented higher oil recovery associated with a lower water injection volume. This shows better efficiency and, consequently, reduction in costs. Considering the wide use of the water injection in oil fields, the positive outcome of the modeling is important, because it shows a case study of increasing of oil recovery achieved simply through better distribution of water injection rates / At? o in?cio da d?cada de 90, a simula??o de fluxo em reservat?rio de petr?leo basicamente utilizava a t?cnica num?rica de diferen?as finitas. Desde ent?o, houve um grande desenvolvimento da tecnologia de simula??o com base em linhas de fluxo, de modo que hoje ela tem sido usada em v?rios casos e se encontra adequada para representar os diversos mecanismos f?sicos que influenciam o fluxo de fluidos no reservat?rio, tais como compressibilidade, capilaridade e segrega??o gravitacional. A simula??o baseada em linhas de fluxo ? uma ferramenta que pode ajudar bastante no gerenciamento de projetos de inje??o de ?gua, pois fornece informa??es importantes n?o disponibilizadas atrav?s da simula??o tradicional de diferen?as finitas e mostra, de forma direta, a influ?ncia entre po?o injetor e po?o produtor. Este trabalho apresenta a aplica??o de uma metodologia existente na literatura para otimizar projeto de inje??o de ?gua em um reservat?rio pertencente a um campo de petr?leo da Bacia Potiguar que possui elevado n?mero de po?os. Esta metodologia considera modifica??es das cotas de inje??o dos po?os ao longo do tempo, com base nas informa??es dispon?veis atrav?s da simula??o por linhas de fluxo. Esta metodologia reduz as vaz?es de inje??o dos po?os de menor efici?ncia e aumenta as vaz?es de inje??o dos po?os mais eficientes. No modelo proposto, a metodologia se mostrou eficaz. As alternativas de otimiza??o apresentaram uma maior recupera??o de ?leo associada a um menor volume de inje??o de ?gua. Isto demonstra uma melhor efici?ncia e, consequentemente, uma redu??o de custos. Considerando a ampla utiliza??o da inje??o de ?gua em campos de petr?leo, o resultado positivo da modelagem ? importante, porque apresenta um estudo de caso de aumento da recupera??o de petr?leo, alcan?ado simplesmente atrav?s de uma melhor distribui??o das vaz?es de inje??o de ?gua

Made available in DSpace on 2014-12-17T14:08:47Z (GMT). No. of bitstreams: 1 MartinhoQAF_DISSERT.pdf: 3517855 bytes, checksum: e2d79876500fdde55b949a6a832b6ff0 (MD5) Previous issue date: 2011-05-27 / Water injection is the most widely used method for supplementary recovery in many oil fields due to various reasons, like the fact that water is an effective displacing agent of low viscosity oils, the water injection projects are relatively simple to establish and the water availability at a relatively low cost. For design of water injection projects is necessary to do reservoir studies in order to define the various parameters needed to increase the effectiveness of the method. For this kind of study can be used several mathematical models classified into two general categories: analytical or numerical. The present work aims to do a comparative analysis between the results presented by flow lines simulator and conventional finite differences simulator; both types of simulators are based on numerical methods designed to model light oil reservoirs subjected to water injection. Therefore, it was defined two reservoir models: the first one was a heterogeneous model whose petrophysical properties vary along the reservoir and the other one was created using average petrophysical properties obtained from the first model. Comparisons were done considering that the results of these two models were always in the same operational conditions. Then some rock and fluid parameters have been changed in both models and again the results were compared. From the factorial design, that was done to study the sensitivity analysis of reservoir parameters, a few cases were chosen to study the role of water injection rate and the vertical position of wells perforations in production forecast. It was observed that the results from the two simulators are quite similar in most of the cases; differences were found only in those cases where there was an increase in gas solubility ratio of the model. Thus, it was concluded that in flow simulation of reservoirs analogous of those now studied, mainly when the gas solubility ratio is low, the conventional finite differences simulator may be replaced by flow lines simulator the production forecast is compatible but the computational processing time is lower. / A inje??o de ?gua ? o m?todo de recupera??o suplementar mais difundido na maioria dos campos de petr?leo, devido a v?rios motivos, como o fato de a ?gua ser um eficiente agente deslocante de ?leos com baixa viscosidade associado ao fato de ser relativamente f?cil de injetar e de existir grande disponibilidade de ?gua a um custo relativamente baixo de se obter. Para o dimensionamento de um projeto de inje??o de ?gua ? necess?rio efetuar um estudo de reservat?rio com o objetivo de se definir os v?rios par?metros necess?rios para aumentar a efic?cia do m?todo. Para este estudo podem ser utilizados v?rios modelos matem?ticos classificados como anal?ticos ou num?ricos. Este trabalho tem como objetivo efetuar uma an?lise comparativa entre os resultados apresentados por um simulador de linhas de fluxo e um simulador convencional por diferen?a finita, que s?o dois tipos de simuladores de fluxo baseados em m?todos num?ricos, para um modelo de um reservat?rio de petr?leo leve submetido ? inje??o de ?gua. Para tanto foram montados dois modelos de reservat?rio, sendo um modelo heterog?neo e outro homog?neo contendo valores m?dios das propriedades de rocha do primeiro modelo. Foram realizadas compara??es dos resultados destes modelos considerando sempre as mesmas condi??es de opera??o. Em seguida foram alterados alguns par?metros de fluido e de rocha em ambos os modelos e efetuadas novamente compara??es de resultados. A partir do planejamento fatorial, realizado para a an?lise de sensibilidade dos par?metros de reservat?rio, foram escolhidos alguns casos para efetuar an?lise da varia??o dos par?metros operacionais escolhidos que foram a vaz?o de inje??o de ?gua e a localiza??o dos canhoneados. Observou-se que os resultados entre os simuladores s?o bastante similares na maioria dos casos estudados, tendo sido encontrado diverg?ncias apenas nos casos em que h? aumento na raz?o de solubilidade de g?s do modelo. Desta maneira foi conclu?do que o simulador convencional por diferen?as finitas pode ser substitu?do por um simulador por linhas de fluxo em reservat?rios semelhantes ao estudado, quando a raz?o de solubilidade possui valores baixos, sem preju?zo aos resultados de produ??o e com menores tempos de processamento computacional. / 2020-01-01

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-27T11:04:15Z No. of bitstreams: 1 BALBINA RAQUEL DE BRITO CORREIA - DISSERTAÇÃO (PPGEM) 2016.pdf: 6215965 bytes, checksum: 1bfd34b81d73a0bb406a5054fcdbdd3a (MD5) / Made available in DSpace on 2018-04-27T11:04:15Z (GMT). No. of bitstreams: 1 BALBINA RAQUEL DE BRITO CORREIA - DISSERTAÇÃO (PPGEM) 2016.pdf: 6215965 bytes, checksum: 1bfd34b81d73a0bb406a5054fcdbdd3a (MD5) Previous issue date: 2016-08-16 / CNPq / A simulação numérica é uma ferramenta utilizada para modelar e estudar reservatórios de petróleo de forma a auxiliar na aplicação de métodos de recuperação suplementar. A injeção de água é o método mais utilizado na recuperação de óleo, devido ao baixo custo de processo, a disponibilidade da água e aos mecanismos de manutenção da pressão e deslocamento de óleo. O presente estudo objetivou estudar o escoamento de óleo e água em um reservatório de óleo pesado, homogêneo, com características do Nordeste brasileiro e modelagem do tipo Black oil, de formato irregular, com o intuito de avaliar o comportamento do reservatório e previsão da recuperação de óleo com a aplicação de injeção isotérmica de água. Para tanto, foi utilizado um simulador numérico, em linguagem C++, com solução das equações governantes pelo método dos volumes finitos e uso de coordenadas generalizadas, a partir de 30 anos de injeção de água, para estudar parâmetros de reservatório e operacionais e avaliar sua influência na recuperação de óleo. Foram realizadas simulações para deliberar sobre a malha do reservatório, estudo do passo de tempo mínimo utilizado nas simulações e efeito de diferentes valores de pressão inicial do reservatório. Dessa forma, foi definida uma malha com 100x50 volumes elementares e o modelo five-spot invertido para avaliar a influência de diferentes valores de permeabilidade absoluta da rocha, grau API do óleo e diferentes vazões de injeção de água, na recuperação de óleo. Foram realizadas análises da localização de poços na malha, a partir da distância entre poços injetores e produtores. A partir dos casos estudados e por meio de gráficos de Volume Poroso Injetado (VPI) versus Volume Poroso de Óleo Recuperado (VPOR), gráficos de Corte de água no tempo e mapas de saturação de água e pressão na formação produtora, ao longo tempo, foi identificado que, no processo de injeção de água, o aumento da permeabilidade absoluta influenciou negativamente e o aumento da vazão de injeção influenciou positivamente a recuperação do óleo, enquanto que o grau API não mostrou influência significativa. Em síntese, com o estudo da alocação dos poços na malha, verificou-se que os poços produtores mais distantes dos poços injetores apresentaram melhores resultados de recuperação de óleo e menor produção de água, pois, o aumento da vazão e a proximidade dos poços, aliada a maiores permeabilidades absoluta da rocha reservatório permitem a ocorrência de fingers viscosos e Breakthrough precoce, fenômenos que reduzem a eficiência do processo de injeção de água. / Numerical simulation is a tool used for modeling and studying oil reservoirs in order to aid in applying additional recovery methods. Water injection is the most common method used in oil recovery due to the low cost process, the availability of water and pressure maintenance and oil displacement mechanisms. This study aimed to study the flow of oil and water in a homogeneous heavy oil reservoir, with Brazilian Northeast characteristics and black oil model, of irregularly form, with the purpose of evaluate the reservoir behavior and prediction of oil recovery due to application of the isothermal water injection. Thus, it was used a numerical simulator, in C++ code, with solution of the governing equations by the finite volume method and the use of generalized coordinates, from 30 years of water injection to study reservoir and opertaing parameters to assess into oil recovery influence. Simulations were accomplished to deliberate on the mesh of the reservoir, minimum time step of the study used in simulations and effects of different initial pressure values of the reservoir. A mesh with 100x50 elementary volumes was defined and inverted five-spot model to evaluate the influence of different absolute values of permeability rock, oil API gravity and different flow rates of water injection on the oil recovery. Wells location analyzes were conducted in the mesh, considering the distance between injection and producers wells. Based on the case studies and using graphs Volume Porous Injected (VPI) and Volume Porous Recovered oil (VPOR), water cut graphs, in time, and reservoir pressure and water saturation maps, over time, it was identified that the water injection process, the absolute permeability increasing have influenced negatively and injection flow rate increased have influenced positively on the oil recovery, while the API gravity has not shown significant influence. In conclusion, it was identified, with the study of allocation of wells in the mesh, that most distance form producing wells of injection wells showed better results on the oil recovery and and reduced water production, therefore, with increasing the flow rate and the proximity of the wells, it combined with larger absolute permeabilities of the reservoir rock, has allowed the occurrence of viscous fingers and early Breakthrough, phenomena which reduce the efficiency of the water injection process.