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The impact of gravity segregation on multiphase non-Darcy flow in hydraulically fractured gas wellsDickins, Mark Ian 10 October 2008 (has links)
Multiphase and non-Darcy flow effects in hydraulically fractured gas wells reduce
effective fracture conductivity. Typical proppant pack laboratory experiments are
oriented in such a way such that phase segregation is not possible, which results in
mixed flow. Tidwell and Parker (1996), however, showed that in proppant packs, gravity
segregation occurs for simultaneous gas and liquid injection at laboratory scale (1500
cm2). Although the impact of gravity on flow in natural fractures has been described,
previous work has not fully described the effect of gravity on multiphase non-Darcy
flow in hydraulic fractures. In this work, reservoir simulation modeling was used to
determine the extent and impact of gravity segregation in a hydraulic fracture at field
scale. I found that by ignoring segregation, effective fracture conductivity can be
underestimated by up to a factor of two.
An analytical solution was developed for uniform flux of water and gas into the fracture.
The solution for pressures and saturations in the fracture agrees well with reservoir
simulation. Gravity segregation occurs in moderate-to-high conductivity fractures. Gravity segregation impacts effective fracture conductivity when gas and liquid are
being produced at all water-gas ratios modeled above 2 Bbls per MMscf. More realistic,
non-uniform-flux models were also run with the hydraulic fracture connected to a gas
reservoir producing water. For constant-gas-rate production, differences in pressure
drop between segregated cases and mixed flow cases range up to a factor of two. As the
pressure gradient in the fracture increases above 1 to 2 psi/ft, the amount of segregation
decreases. Segregation is also less for fracture half-length-to-height ratios less than or
close to two. When there is less segregation, the difference in effective conductivity
between the segregated and mixed flow cases is reduced. I also modeled the water
injection and cleanup phases for a typical slickwater fracture treatment both with and
without gravity effects and found that for cases with segregation, effective fracture
conductivity is significantly higher than the conductivity when mixed flow occurs.
Gravity segregation is commonly ignored in design and analysis of hydraulically
fractured gas wells. This work shows that segregation is an important physical process
and it affects effective fracture conductivity significantly. Hydraulic fracture treatments
can be designed more effectively if effective fracture conductivity is known more
accurately.
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Estudo da perda de carga e calor no po?o injetor no processo De drenagem gravitacional assistida por vapor (SAGD)Fernandes, Glydianne Mara Di?genes 09 September 2011 (has links)
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Previous issue date: 2011-09-09 / The oil companies in the area in general are looking for new technologies that can
increase the recovery factor of oil contained in reservoirs. These investments are mainly
aimed at reducing the costs of projects which are high. Steam injection is one of these special
methods of recovery in which steam is injected into the reservoir in order to reduce the
viscosity of the oil and make it more mobile. The process assisted gravity drainage steam
(SAGD) using steam injection in its mechanism, as well as two parallel horizontal wells. In
this process steam is injected through the horizontal injection well, then a vapor chamber is
formed by heating the oil in the reservoir and, by the action of gravitational forces, this oil is
drained down to where the production well. This study aims to analyze the influence of
pressure drop and heat along the injection well in the SAGD process. Numerical simulations
were performed using the thermal simulator STARS of CMG (Computer Modeling Group).
The parameters studied were the thermal conductivity of the formation, the flow of steam
injection, the inner diameter of the column, the steam quality and temperature. A factorial
design was used to verify the influence of the parameters studied in the recovery factor. We
also analyzed different injection flow rates for the model with pressure drop and no pressure
drop, as well as different maximum flow rates of oil production. Finally, we performed an
economic analysis of the two models in order to check the profitability of the projects studied.
The results showed that the pressure drop in injection well have a significant influence on the
SAGD process. / As empresas da ?rea de petr?leo em geral est?o ? procura de novas tecnologias que
possam elevar o fator de recupera??o do ?leo contido em seus reservat?rios. Esses
investimentos t?m como principal objetivo reduzir os custos dos projetos de produ??o de
petr?leo, que s?o elevados. A inje??o de vapor representa um desses m?todos especiais de
recupera??o, em que vapor ? injetado no reservat?rio com o objetivo de reduzir a viscosidade
do ?leo e torn?-lo mais m?vel. O processo de drenagem gravitacional assistida por vapor
(SAGD) utiliza a inje??o de vapor em seu mecanismo, assim como dois po?os horizontais
paralelos. Neste processo o vapor ? injetado atrav?s do po?o injetor horizontal, em seguida
uma c?mara de vapor ? formada no reservat?rio aquecendo o ?leo e, pela a??o das for?as
gravitacionais, este ?leo ? drenado para baixo onde se encontra o po?o produtor. O presente
trabalho tem como objetivo analisar a influ?ncia da perda de carga e calor ao longo do po?o
injetor no processo SAGD. Foram realizadas simula??es num?ricas atrav?s do simulador
t?rmico STARS da CMG (Computer Modelling Group). Os par?metros estudados foram ?
condutividade t?rmica da forma??o, a vaz?o de inje??o de vapor, o di?metro interno da
coluna, o t?tulo do vapor e a temperatura. Um planejamento fatorial foi utilizado para verificar
a influ?ncia dos par?metros estudados no fator de recupera??o. Foram tamb?m analisadas
diferentes vaz?es de inje??o para o modelo com perda de carga e sem perda de carga, assim
como diferentes vaz?es m?ximas de produ??o de ?leo. Finalmente, foi realizada uma an?lise
econ?mica dos dois modelos com a finalidade de analisar a rentabilidade dos projetos
estudados. Os resultados mostraram que as perdas de carga no po?o injetor t?m uma
influ?ncia significativa no processo SAGD.
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[pt] IMPACTO DA SEGREGAÇÃO GRAVITACIONAL NA RECUPERAÇÃO DE ÓLEO NO CASO DE INJEÇÃO WAG EM CENÁRIO TÍPICO DO PRÉ-SAL / [en] INFLUENCE OF GRAVITY SEGREGATION ON OIL RECOVERY FOR WAG INJECTION IN A TIPICAL PRE-SALT CASECLEWERTON TEIXEIRA DE SOUZA BRAGA 16 November 2021 (has links)
[pt] Na última década a participação dos campos do Pré-Sal brasileiro na produção
nacional de petróleo aumentou substancialmente, tornando esses campos
responsáveis por mais da metade da produção nacional e com perspectiva de
crescimento para os próximos anos. Os reservatórios de petróleo encontrados
nessa região são caracterizados por espessuras que podem variar de poucas
dezenas a centenas de metros, rochas com boas qualidades permo-porosas e
presença de óleo leve, com elevado teor de gás associado e com contaminantes
como CO2. Por estas características, diversos sistemas de produção instalados
nestes reservatórios foram preparados e deverão adotar o método de recuperação
suplementar com injeção alternada de água e gás. No presente trabalho
foi feita uma análise paramétrica sobre a influência que propriedades
de reservatório como espessura porosa, permeabilidade horizontal, permeabilidade
vertical e razão kv/kh, e variáveis operacionais como vazão de operação,
razão WAG e tempo de ciclo podem gerar no fator de recuperação em um
cenário de produção típico do Pré-Sal brasileiro com e sem o efeito de segregação
gravitacional. Pela comparação dos resultados em diversos casos de
simulação numérica, foi possível identificar as variáveis com maior impacto e
a influência decorrente do efeito gravitacional. Em seguida, a partir de uma
análise de sensibilidade foi gerada uma equação para estimar o fator de recuperação
em função das variáveis selecionadas. Números adimensionais propostos
na literatura para avaliar a segregação gravitacional de fluidos em meio poroso
foram calculados e utilizados para gerar outras equações para estimar o fator
de recuperação. As estimativas do fator de recuperação feitas por cada função
foram comparadas com os valores simulados para cada caso e foram identificadas
as funções que apresentaram as estimativas mais próximas. Tais funções
poderão ser utilizadas para estimar o fator de recuperação no cenário proposto
e com aplicação em análises preliminares para projetos de desenvolvimento de
campos de petróleo. / [en] In the last decade, the contribution of Brazilian pre-salt fields in the
national oil production has increased substantially, setting these fields as
responsible for more than half of the national production and with growth
perspectives for years to come. The oil reservoirs found in this region are
characterized by thicknesses which can vary from a few tens to hundreds of
meters, rocks with favorable matrix properties, and the presence of light oil
with a high associated gas content and contaminants such as CO2. Due to these
characteristics, several production systems installed in these reservoirs were
prepared and should adopt water alternating gas injection as supplementary
recovery method. In the present study, a parametric analysis was performed
on the influence that reservoir properties as porous thickness, horizontal
permeability, vertical permeability, and kv/kh ratio, and operating variables
as operating flow rate, WAG ratio, and cycle time can provoke in the recovery
factor in a typical Brazilian pre-salt production scenario with and without the
effect of gravitational segregation. By comparing the results in several cases of
numerical simulation it was possible to identify the variables with the greatest
impact and the influence of the gravity effect on recovery. From a sensitivity
analysis, equations to estimate the recovery factor as a function of the selected
variables or as a function of dimensionless numbers proposed in the literature
to assess the gravitational segregation of fluids in porous media were adjusted.
The recovery factor estimates made with each function were compared with
the simulated values for each case and the functions that presented the best
estimates were identified. Such functions can be used to estimate the recovery
factor in the application scenario with application in preliminary analyzes for
oil field development projects.
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Estudo param?trico da recupera??o de ?leo no processo de drenagem gravitacional com inje??o de CO2Pinto, Tommy de Almeida 27 April 2009 (has links)
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Previous issue date: 2009-04-27 / Petr?leo Brasileiro SA - PETROBRAS / The gas injection has become the most important IOR process in the United States. Furthermore, the year 2006 marks the first time the gas injection IOR production has surpassed that of steam injection. In Brazil, the installation of a petrochemical complex in the Northeast of Brazil (Bahia State) offers opportunities for the injection of gases in the fields located in the Rec?ncavo Basin. Field-scale gas injection applications have almost always been associated with design and operational difficulties. The mobility ratio, which controls the volumetric sweep, between the injected gas and displaced oil bank in gas processes, is typically unfavorable due to the relatively low viscosity of the injected gas. Furthermore, the difference between their densities results in severe gravity segregation of fluids in the reservoirs, consequently leading to poor control in the volumetric sweep. Nowadays, from the above applications of gas injection, the WAG process is most popular. However, in attempting to solve the mobility problems, the WAG process gives rise to other problems associated with increased water saturation in the reservoir including diminished gas injectivity and increased competition to the flow of oil. The low field performance of WAG floods with oil recoveries in the range of 5-10% is a clear indication of these problems. In order to find na effective alternative to WAG, the Gas Assisted Gravity Drainage (GAGD) was developed. This process is designed to take advantage of gravity force to allow vertical segregation between the injected CO2 and reservoir crude oil due to their density difference. This process consists of placing horizontal producers near the bottom of the pay zone and injecting g?s through existing vertical wells in field. Homogeneous models were used in this work which can be extrapolated to commercial application for fields located in the Northeast of Brazil. The simulations were performed in a CMG simulator, the STARS 2007.11, where some parameters and their interactions were analyzed. The results have shown that the CO2 injection in GAGD process increased significantly the rate and the final recovery of oil / A inje??o de g?s tem sido o m?todo de recupera??o mais utilizado nos Estados Unidos e o ano de 2006 marca a primeira vez em que a produ??o proveniente dos processos de inje??o de g?s superou os de inje??o de vapor. No Brasil, a instala??o do complexo petroqu?mico, no estado da Bahia, oferece oportunidades para inje??o de g?s na Bacia do Rec?ncavo. As aplica??es de inje??o de g?s em campo foram quase sempre associadas com dificuldades operacionais e de projetos. A raz?o de mobilidade, que controla a varredura volum?trica, entre o g?s injetado e o banco de ?leo deslocado, ? tipicamente desfavor?vel devido ? baixa viscosidade do g?s. Al?m de que a diferen?a entre as densidades conduz a segrega??o gravitacional severa dos fluidos no reservat?rio e consequentemente, levando a um pobre controle na varredura volum?trica. Atualmente, grande parte dos projetos de inje??o de g?s no mundo ? do tipo WAG. Entretanto, na tentativa de resolver os problemas de mobilidade, o processo WAG causa outros problemas como o aumento na satura??o de ?gua no reservat?rio, incluindo a diminui??o na injetividade do g?s e aumento da competi??o no fluxo do ?leo. O baixo desempenho na recupera??o de ?leo deste processo no campo, na ordem de 5 a 10%, ? uma clara indica??o destes problemas. A fim de encontrar uma alternativa eficaz para o WAG, o processo de drenagem gravitacional assistida por inje??o de g?s (GAGD) foi desenvolvido. O processo GAGD ? projetado para tomar vantagem da for?a gravitacional causando assim, a segrega??o vertical entre o CO2 injetado e a reserva de ?leo devido ? diferen?a de densidades. Este processo consiste na coloca??o de po?os produtores horizontais pr?ximos a parte inferior da zona de ?leo e inje??o de g?s atrav?s de po?os verticais existentes em campo. Modelos homog?neos foram utilizados neste trabalho os quais podem ser extrapolados para aplica??o comercial em campos localizados no nordeste brasileiro. As simula??es foram realizadas no simulador da CMG STARS 2007.11, sendo analisados alguns par?metros e suas intera??es. Os resultados mostraram que a inje??o de CO2 no processo GAGD aumentou significativamente a vaz?o e a recupera??o final de ?leo
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An?lise param?trica da simula??o composicional do processo de Drenagem Gravitacional Assistida por G?s (GAGD)Bautista, Ernesto Vargas 26 February 2010 (has links)
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Previous issue date: 2010-02-26 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In Brazil and around the world, oil companies are looking for, and expected development of new technologies and processes that can increase the oil recovery factor in mature reservoirs,
in a simple and inexpensive way. So, the latest research has developed a new process called Gas Assisted Gravity Drainage (GAGD) which was classified as a gas injection IOR. The
process, which is undergoing pilot testing in the field, is being extensively studied through physical scale models and core-floods laboratory, due to high oil recoveries in relation to
other gas injection IOR. This process consists of injecting gas at the top of a reservoir through horizontal or vertical injector wells and displacing the oil, taking advantage of natural gravity
segregation of fluids, to a horizontal producer well placed at the bottom of the reservoir. To study this process it was modeled a homogeneous reservoir and a model of multi-component
fluid with characteristics similar to light oil Brazilian fields through a compositional simulator, to optimize the operational parameters. The model of the process was simulated in
GEM (CMG, 2009.10). The operational parameters studied were the gas injection rate, the type of gas injection, the location of the injector and production well. We also studied the
presence of water drive in the process. The results showed that the maximum vertical spacing between the two wells, caused the maximum recovery of oil in GAGD. Also, it was found that the largest flow injection, it obtained the largest recovery factors. This parameter controls the speed of the front of the gas injected and determined if the gravitational force dominates or not the process in the recovery of oil. Natural gas had better performance than CO2 and that the presence of aquifer in the reservoir was less influential in the process. In economic
analysis found that by injecting natural gas is obtained more economically beneficial than CO2 / No Brasil e no mundo, as empresas de petr?leo est?o ? procura, desenvolvimento e ? espera de novas tecnologias e processos que possam elevar o fator de recupera??o de ?leo em seus
reservat?rios, com um equilibrado custo-benef?cio. Na procura de novas tecnologias foi desenvolvido o processo de drenagem gravitacional assistida por g?s (GAGD Gas Assisted Gravity Drainage) que foi classificado dentro dos m?todos de recupera??o avan?ada de ?leo. O processo GAGD, que se encontra em fase de teste piloto em campo, est? sendo muito
estudado atrav?s de modelos f?sicos em escala de laborat?rio e em testemunhos, isto devido ?s altas recupera??es de ?leo em rela??o aos outros processos de inje??o de g?s. Este m?todo
consiste em injetar g?s no topo de um reservat?rio atrav?s de po?os injetores verticais ou horizontais e deslocar o ?leo, aproveitando a segrega??o gravitacional natural dos fluidos,
para um po?o produtor horizontal colocado na base do reservat?rio. Para estudar este processo foi idealizado um reservat?rio homog?neo e um modelo de fluido multicomponente com caracter?sticas parecidas aos campos de ?leo leve do Brasil para que, atrav?s de um simulador composicional, se analisem os par?metros operacionais. O processo foi simulado no programa comercial GEM da CMG (Computer Modelling Group). Os par?metros operacionais estudados foram a vaz?o de inje??o de g?s, o tipo de g?s injetado (g?s natural e CO2), a
localiza??o do po?o injetor e do po?o produtor. Tamb?m foi estudada a presen?a de aq??fero no processo. Os resultados mostraram que o m?ximo espa?amento vertical entre os dois
po?os, provocou a m?xima recupera??o de ?leo no GAGD. Tamb?m, verificou-se que a maiores vaz?es de inje??o, se obtiveram os maiores fatores de recupera??o. Este par?metro
controlou a velocidade da frente do g?s injetado e determinou se a for?a gravitacional domina ou n?o sobre o processo na recupera??o de ?leo. O g?s natural teve melhor desempenho que o CO2 e que, a presen?a de aq??fero no reservat?rio influenciou pouco no processo. Na an?lise econ?mica verificou-se que a inje??o de g?s natural obteve o melhor beneficio econ?mico que com CO2
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Estudo da segrega??o gravitacional do processo de inje??o de vapor em reserv?t?rios heterog?neosSantana, Keila Regina 31 July 2009 (has links)
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Previous issue date: 2009-07-31 / Petr?leo Brasileiro SA - PETROBRAS / Due to reservoirs complexity and significantly large reserves, heavy oil recovery has become one of the major oil industry challenges. Thus, thermal methods have been widely used as a strategic method to improve heavy oil recovery. These methods improve oil displacement through viscosity reduction, enabling oil production in fields which are not considered commercial by conventional recovery methods. Among the thermal processes, steam flooding is the most used today. One consequence in this process is gravity segregation, given by difference between reservoir and injected fluids density. This phenomenon may be influenced by the presence of reservoir heterogeneities. Since most of the studies are carried out in homogeneous reservoirs, more detailed studies of heterogeneities effects in the reservoirs during steam flooding are necessary, since most oil reservoirs are heterogeneous. This paper presents a study of reservoir heterogeneities and their influence in gravity segregation during steam flooding process. In this study some heterogeneous reservoirs with physical characteristics similar those found in the Brazilian Northeast Basin were analyzed. To carry out the simulations, it was used the commercial simulator STARS by CMG (Computer Modeling Group) - version 2007.11. Heterogeneities were modeled with lower permeability layers. Results showed that the presence of low permeability barriers can improve the oil recovery, and reduce the effects of gravity segregation, depending on the location of heterogeneities. The presence of these barriers have also increased the recovered fraction even with the reduction of injected steam rate / Devido a complexidade dos reservat?rios e as reservas significativamente grandes, a recupera??o de ?leos pesados tem se tornado um dos grandes desafios da ind?stria petrol?fera. Os processos de recupera??o t?rmica t?m sido largamente empregados como um m?todo estrat?gico para melhorar a recupera??o de ?leo pesado. Estes melhoram o escoamento de ?leos atrav?s da redu??o da viscosidade, viabilizando a produ??o de petr?leo em campos considerados n?o comerciais pelos m?todos convencionais de recupera??o. Entre os m?todos t?rmicos, a inje??o de vapor ? o mais utilizado atualmente. Uma consequ?ncia inerente a este processo ? a segrega??o gravitacional, dada pela diferen?a de densidades dos fluidos do reservat?rio e o injetado. Este fen?meno ? fortemente influenciado pela presen?a de heterogeneidades. Como a maior parte dos estudos ? realizada em reservat?rios homog?neos, necessita-se de um estudo mais detalhado dos efeitos das heterogeneidades nos reservat?rios durante a inje??o de vapor, j? que a maioria dos reservat?rios de petr?leo s?o heterog?neos. Este trabalho apresenta um estudo da influ?ncia da presen?a de heterogeneidades na segrega??o gravitacional durante o processo de inje??o cont?nua de vapor. Os modelos estudados representam reservat?rios heterog?neos com caracter?sticas similares ?s encontradas no Nordeste brasileiro. Para a realiza??o das simula??es, foi utilizado o simulador comercial STARS (Steam, Thermal, and Advanced Processes Reservoir Simulator) do grupo CMG (Computer Modelling Group) vers?o 2007.11. As heterogeneidades foram modeladas como camadas de baixa permeabilidade. Os resultados mostraram que a presen?a de barreiras de baixa permeabilidade pode melhorar a recupera??o de ?leo, al?m de reduzir os efeitos da segrega??o gravitacional, dependendo da localiza??o da heterogeneidade. A presen?a dessas barreiras tamb?m permitiu o aumento da fra??o recuperada mesmo com a redu??o da vaz?o de inje??o do vapor
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