Experimental Observations Of Miscible Displacement Of Heavy Oils With Hydrocarbon Solvents
- Dalia Salama | Apostolos Kantzas (University of Calgary)
- Document ID
- Society of Petroleum Engineers
- SPE International Thermal Operations and Heavy Oil Symposium, 1-3 November, Calgary, Alberta, Canada
- Publication Date
- Document Type
- Conference Paper
- 2005. SPE/PS-CIM/CHOA International Thermal Operations and Heavy Oil Symposium
- 5.6.5 Tracers, 5.8.5 Oil Sand, Oil Shale, Bitumen, 5.7.2 Recovery Factors, 5.2.2 Fluid Modeling, Equations of State, 2.4.3 Sand/Solids Control, 1.6.9 Coring, Fishing, 5.4 Enhanced Recovery, 5.3.9 Steam Assisted Gravity Drainage, 5.4.6 Thermal Methods, 5.4.2 Gas Injection Methods, 5.4.1 Waterflooding, 5.3.1 Flow in Porous Media, 5.4.9 Miscible Methods, 5.4.7 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex)
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The increased interest in secondary production (or post-cold production) of heavy oil and the current rise of oil prices has renewed interest in solvent-based methods for heavy oil recovery.Although the Vapor Extraction (VAPEX) process is the most heavily favored process for potential field application, other methods are also worth investigating.Moreover, the relative merit of mass transfer and viscous mechanisms in the overall recovery efficiency remains a topic of debate in the literature.
This paper is a small part of a greater effort to study mass transfer phenomena in heavy oil/bitumen solvent systems.A series of core flooding experiments were performed whereby liquid solvents (octane, pentane) displaced heavy oil (12Pa.s).Different configurations and displacement rates were employed and heavy oil recovery factors were determined.Solvent concentrations in the effluent oil-solvent mixtures were accurately evaluated using the non-intrusive Nuclear Magnetic Resonance (NMR) technique and conventional density measurements.
Mass transfer analysis was performed in an effort to determine dispersion coefficients.
With the era of conventional oil appearing to be coming to an end, attention has turned to heavy oil production and enhanced oil recovery (EOR).Heavy oil and oil sands are destined to play an increasingly important role in the oil supply in the world and they will be in center-stage in the development of the oil industry in Canada.One third of the world's oil is in Canada in the form of heavy oil and bitumen.The heavy oil resources of the world total about ten trillion barrels, nearly three times the conventional oil-in-place in the world.Alberta contains nearly two trillion barrels of oil.Approximately one fourth of the oil production of Canada is from oil sands (1).
In-situ recovery processes can be classified into two categories: thermal and non-thermal. Thermal recovery processes utilize heat to reduce the viscosity of the heavy oil in situ, thus mobilizing the heavy oil. Examples of thermal processes are Cyclic Steam Simulation (CSS), Steam Assisted Gravity Drainage (SAGD) and Steam Flooding. On the other hand, non-thermal processes rely on dilution of the oil rather than heat to reduce the heavy oil viscosity. Examples of such processes are CO2 Injection, Miscible Floods and Vapour Extraction (VAPEX).
Displacement in the case of immiscible floods, such as water flooding, is generally not complete, but a fluid can be displaced completely from the pores by another fluid that is miscible with it in all proportions. In the case of miscible fluids there are no residual saturations (2). Hence, solvent floods present an attractive in-situ process for the recovery of the heavy oil. However, the major challenge in miscible floods is for the miscible phase to access a significant fraction of the resident oil.
In solvent-based EOR techniques, several mechanisms affect the rate of oil recovery, given that accessibility is provided: mass transfer, viscous forces and gravity drainage. The solvent diffuses and/or disperses into the heavy oil, reducing its viscosity. The solvent-oil mixture then drains and is recovered from the production well.
In this paper, the presented experiments focus on investigating the mass transfer process, taking place in miscible solvent floods, by experimentally observing the miscible displacement of heavy oils by hydrocarbon solvents.
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