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Collaborating Authors
Results
New Paradigm in the Understanding of In Situ Combustion: The Nature of the Fuel and the Important Role of Vapor Phase Combustion
Gutiérrez, Dubert (AnBound Energy Inc.) | Mallory, Don (University of Calgary) | Moore, Gord (University of Calgary) | Mehta, Raj (University of Calgary) | Ursenbach, Matt (University of Calgary) | Bernal, Andrea (AnBound Energy Inc.)
Abstract Historically, the air injection literature has stated that the main fuel for the in situ combustion (ISC) process is the carbon-rich, solid-like residue resulting from distillation, oxidation, and thermal cracking of the residual oil near the combustion front, commonly referred to as "coke". At first glance, that assumption may appear sound, since many combustion tube tests reveal a "coke bank" at the point of termination of the combustion front. However, when one examines both the laboratory results from tests conducted on various oils at reservoir conditions, and historical field data from different sources, the conclusion may be different than what has been assumed. For instance, combustion tube tests performed on light oils rarely display any significant sign of coke deposition, which would make them poor candidates for air injection; nevertheless, they have been some of the most successful ISC projects. It is proposed that the main fuel consumed by the ISC process may not be the solid-like residue, but light hydrocarbon fractions that experience combustion reactions in the gas phase. This vapor fuel forms as a result of oxidative and thermal cracking of the original and oxidized oil fractions. An analysis of different oxidation experiments performed on oil samples ranging from 6.5 to 38.8°API, at reservoir pressures, indicates that this behavior is consistent across this wide density spectrum, even in the absence of coke. While coke will form as a result of the low temperature oxidation of heavy oil fractions, and while thermal cracking of those fractions on the pathway to coke may produce vapor components which may themselves burn, the coke itself is not likely the main fuel for the process, particularly for lighter oils. This paper presents a new theory regarding the nature and formation of the main fuel utilized by the ISC process. It discusses the fundamental concepts associated with the proposed theory, and it summarizes the experimental laboratory evidence and the field evidence which support the concept. This new theory does still share much common ground with the current understanding of the ISC process, but with a twist. The new insights result from the analysis of laboratory tests performed on lighter oils at reservoir pressures; data which was not available at the time that the original ISC concepts were developed. This material suggests a complete change to one of the most important paradigms related to the ISC process, which is the nature and source of the fuel. This affects the way we understand the process, but provides a unified and consistent theory, which is important for the modelling efforts and overall development of a technology that has the potential to unlock many reserves from conventional and unconventional reservoirs.
- North America > United States (1.00)
- Europe (1.00)
- North America > Canada > Alberta (0.94)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.90)
- Geology > Geological Subdiscipline (0.67)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.94)
- North America > United States > Nebraska > Sloss Field (0.99)
- North America > Canada > Alberta > Athabasca Oil Sands > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > United States > South Dakota > Williston Basin > Buffalo Field > Red River Formation (0.94)
- North America > United States > North Dakota > Medicine Pole Hills Field (0.94)
Abstract Hydrochloric acid is commonly used in acid fracturing. Given that the interaction between acid and rock affects multiphase flow behaviors, it’s important to thoroughly understand the relevant phenomena. Darcy–Brinkman–Stokes (DBS) method is most effective to describe the matrix–fracture system among the proposed models. The objective of this study is to analyze the impact of acid–rock interaction on multiphase flow behavior, by developing a pore–scale numerical model applying DBS method. The new pore–scale model is developed based on OpenFOAM, which is an open source platform for the prototyping of diverse flow mechanisms. The developed simulation model describes the fully–coupled mass balance equation and the chemical reaction of carbonate acidization in an advection–diffusion regime. Volume of Fluid (VOF) method is employed to track liquid and gas phase interface on fixed Eulerian grids. Here, penalization method is applied to describe the wettability condition on immersed boundaries. To compute the numerical solutions of discretized equations, finite volume method is applied, where the equations of saturation, concentration, and diffusion are solved successively, and momentum equation is solved by using Pressure–Implicit with Splitting of Operators (PISO) method, respectively. The simulation results computed by this numerical model have been validated by experimental results. Different injection velocities and the second Damkohler numbers have been simulated to investigate their effects on the evolving porosity and rock surface area. The newly developed pore–scale model in this research provides the fundamental knowledge of physical–and–chemical phenomena of acid–rock interaction and their impact on acid transport. The modelling results describing mineral aci dization will help us to implement an effective fracturing project while reducing environment impacts.
- Geology > Mineral (0.72)
- Geology > Rock Type > Sedimentary Rock (0.46)