Experiment Observations of Miscible Displacement of Heavy Oil With Hydrocarbon Solvents
- Dennis Denney (JPT Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- April 2006
- Document Type
- Journal Paper
- 102 - 104
- 2006. Society of Petroleum Engineers
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- 75 since 2007
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This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 97854, "Experimental Observations of Miscible Displacement of Heavy Oils With Hydrocarbon Solvents," by D. Salama and A. Kantzas, U. of Calgary, prepared for the 2005 SPE International Thermal Operations and Heavy Oil Symposium, Calgary, 1-3 November.
The increased interest in secondary production (or post-cold production) of heavy oil and the rise of oil prices have renewed interest in solvent-based methods for heavy-oil recovery. Although the vapor-extraction (vapex) process is favored, other methods are worth investigating. Also, the relative merit of mass-transfer and viscous mechanisms in the overall recovery efficiency remains a topic of debate. This study of mass-transfer phenomena in heavy-oil/ and bitumen/solvent systems was performed in an effort to determine dispersion coefficients.
Heavy oil and oil sands will be an important part of Canada’s oil supply. One-third of the world’s oil is in Canada in the form of heavy oil and bitumen. The world’s heavy-oil resources total approximately 10 trillion bbl, nearly three times the conventional oil in place in the world. Alberta contains nearly 2 trillion bbl of oil. Approximately one-fourth of the oil production of Canada is from oil sands.
Here, in-situ recovery processes are thermal or nonthermal. Thermal processes use heat to reduce the viscosity of the heavy oil in situ, thus mobilizing the heavy oil. Examples include cyclic-steam stimulation, steam-assisted gravity drainage, and steamflooding. Nonthermal processes rely on dilution of the oil to reduce the heavy-oil viscosity. Examples include CO2 injection, miscible floods, and vapex.
Displacement in the case of immiscible floods, such as waterflooding, generally is not complete, but a fluid can be displaced completely from the pores by a miscible fluid. In the case of miscible fluids, there are no residual saturations. Hence, sol-vent 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 enhanced-oil-recovery techniques, several mechanisms affect the rate of oil recovery, given that accessibility is provided. These mechanisms include 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. This study focused on the mass-transfer process in miscible sol-vent floods by experimentally observing the miscible displacement of heavy oils by hydrocarbon solvents.
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