Abstract
Understanding of flow in subsurface porous media is of importance for several reasons. Recovery of petroleum stored in the underground has been a vital source of energy for the last 100 years or so, and it likely to be so for several decades to come. Also, the subsurface stores vast amounts of geothermal energy that can be exploited. Further, ground water is the main water supply in large parts of the world, and thus contamination of water resources by industrial pollution or nuclear waste is a major concern. Geological storage of CO{sub 2} is one of the proposed solutions to reduce global warming, which is related to an increase in the concentration of CO{sub 2} in the atmosphere. These are some of the motivating factors for getting better knowledge of processes that takes place in porous media. The main focus in this work is recovery of hydrocarbons, however, many of the results can be relevant for other applications as well. In the introductory chapter, a brief overview of important concepts in reservoir technology that serve as a motivating background for the thesis is provided. Some of the concepts will be studied in more depth in the following chapters. A petroleum
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Citation Formats
Keilegavlen, Eirik.
Robust control volume methods for reservoir simulation on challenging grids.
Norway: N. p.,
2010.
Web.
Keilegavlen, Eirik.
Robust control volume methods for reservoir simulation on challenging grids.
Norway.
Keilegavlen, Eirik.
2010.
"Robust control volume methods for reservoir simulation on challenging grids."
Norway.
@misc{etde_1010768,
title = {Robust control volume methods for reservoir simulation on challenging grids}
author = {Keilegavlen, Eirik}
abstractNote = {Understanding of flow in subsurface porous media is of importance for several reasons. Recovery of petroleum stored in the underground has been a vital source of energy for the last 100 years or so, and it likely to be so for several decades to come. Also, the subsurface stores vast amounts of geothermal energy that can be exploited. Further, ground water is the main water supply in large parts of the world, and thus contamination of water resources by industrial pollution or nuclear waste is a major concern. Geological storage of CO{sub 2} is one of the proposed solutions to reduce global warming, which is related to an increase in the concentration of CO{sub 2} in the atmosphere. These are some of the motivating factors for getting better knowledge of processes that takes place in porous media. The main focus in this work is recovery of hydrocarbons, however, many of the results can be relevant for other applications as well. In the introductory chapter, a brief overview of important concepts in reservoir technology that serve as a motivating background for the thesis is provided. Some of the concepts will be studied in more depth in the following chapters. A petroleum reservoir consists of rock perforated by small channels, or pores, that are filled with hydrocarbons. To act as a reservoir, the pores must be connected, so that the fluids can flow. The rock in a reservoir has originated from sedimentary deposition processes that took place millions of years ago. It therefore has a layered structure, where each layer consists of a different type of rock. Even though numerical simulations successfully have been applied in the industry for decades, there is a constant need for further improvements of the methods. The work can be aimed at developing new techniques, or to extend already existing methods to new areas of applications. Also, it is important to achieve a better understanding of properties and limitations of already existing approaches. The focus in this work has been development and analysis of a class of numerical schemes known as control volume methods, which are prevailing in commercial reservoir simulators. In the present work, a broad range of subjects related to control volume methods have been investigated. The main computational overhead in reservoir simulations, come from solution of linear systems of equations. So far, most simulation grids have been structured, partly due to a lack of efficient linear solvers that allows for more general grid structures. However, usage of such general solvers seems to become more widespread, and thus flexible grids can be used to a larger extent. This will render possible a better representation of complex geological structures. In this work, the robustness of control volume methods on realistic and flexible grids is analyzed. Moreover, applications of transport schemes designed for simulating EOR-scenarios with adverse mobility ratios on unstructured grids are studied. All the recovered hydrocarbons are transported through wells. A proper description of flow in near-well regions is therefore a key issue. In the vicinity of a well, the flow rates are high, and the flow pattern radial like. Moreover, to optimize the recovery rate, skew and horizontal wells are drilled, yielding highly heterogeneous near-well regions. The numerical schemes must be adapted to these challenges. In this work, we perform systematic tests of different grids and discretization techniques in the vicinity of wells. (AG)}
place = {Norway}
year = {2010}
month = {Feb}
}
title = {Robust control volume methods for reservoir simulation on challenging grids}
author = {Keilegavlen, Eirik}
abstractNote = {Understanding of flow in subsurface porous media is of importance for several reasons. Recovery of petroleum stored in the underground has been a vital source of energy for the last 100 years or so, and it likely to be so for several decades to come. Also, the subsurface stores vast amounts of geothermal energy that can be exploited. Further, ground water is the main water supply in large parts of the world, and thus contamination of water resources by industrial pollution or nuclear waste is a major concern. Geological storage of CO{sub 2} is one of the proposed solutions to reduce global warming, which is related to an increase in the concentration of CO{sub 2} in the atmosphere. These are some of the motivating factors for getting better knowledge of processes that takes place in porous media. The main focus in this work is recovery of hydrocarbons, however, many of the results can be relevant for other applications as well. In the introductory chapter, a brief overview of important concepts in reservoir technology that serve as a motivating background for the thesis is provided. Some of the concepts will be studied in more depth in the following chapters. A petroleum reservoir consists of rock perforated by small channels, or pores, that are filled with hydrocarbons. To act as a reservoir, the pores must be connected, so that the fluids can flow. The rock in a reservoir has originated from sedimentary deposition processes that took place millions of years ago. It therefore has a layered structure, where each layer consists of a different type of rock. Even though numerical simulations successfully have been applied in the industry for decades, there is a constant need for further improvements of the methods. The work can be aimed at developing new techniques, or to extend already existing methods to new areas of applications. Also, it is important to achieve a better understanding of properties and limitations of already existing approaches. The focus in this work has been development and analysis of a class of numerical schemes known as control volume methods, which are prevailing in commercial reservoir simulators. In the present work, a broad range of subjects related to control volume methods have been investigated. The main computational overhead in reservoir simulations, come from solution of linear systems of equations. So far, most simulation grids have been structured, partly due to a lack of efficient linear solvers that allows for more general grid structures. However, usage of such general solvers seems to become more widespread, and thus flexible grids can be used to a larger extent. This will render possible a better representation of complex geological structures. In this work, the robustness of control volume methods on realistic and flexible grids is analyzed. Moreover, applications of transport schemes designed for simulating EOR-scenarios with adverse mobility ratios on unstructured grids are studied. All the recovered hydrocarbons are transported through wells. A proper description of flow in near-well regions is therefore a key issue. In the vicinity of a well, the flow rates are high, and the flow pattern radial like. Moreover, to optimize the recovery rate, skew and horizontal wells are drilled, yielding highly heterogeneous near-well regions. The numerical schemes must be adapted to these challenges. In this work, we perform systematic tests of different grids and discretization techniques in the vicinity of wells. (AG)}
place = {Norway}
year = {2010}
month = {Feb}
}