Steam Injection: Steam injection and flooding are very effective in recovering heavy viscous crudes. Thermal recovery is applicable for individual well stimulation or field-wide flooding. Incremental production cost is estimated at $3 to $6 per barrel.
In-Situ Combustion: This process attempts to recover oil by burning a portion of in-place crude. Air or oxygen is injected to facilitate burning. The process is very complex involving multiphase flow of flue gases, volatile hydrocarbons, steam, hot water, and oil.
Its performance in general has been insufficient to make it economically attractive to producers. Incremental production cost is estimated at $5 to $10 per barrel.
Examples of DOE projects in this area include:
A thermal recovery project at West Hackberry, Louisiana, is demonstrating the improved oil recovery potential of air injection for many oil reservoirs throughout the U.S. Gulf Coast.
Amoco (now BP Amoco) is currently field testing whether air injection can be combined with the double displacement process, which is gas displacement of a water-invaded column to generate tertiary oil recovery through gravity drainage. Louisiana State University also participates in the project by providing independent study and technology transfer.
The project goal is to create a new EOR process for light oil reservoirs that would be profitable in today's economic environment.
A key aspect of the process is the selection of target reservoirs that possess sufficient reservoir temperature to consume oxygen through spontaneous in-situ combustion.
Without in-situ combustion, unreacted oxygen in the produced gas could lead to emulsions, corrosion, and, in large enough concentrations, explosions in the production equipment.
While air injection has been accepted for heavy oil reservoirs, the West Hackberry project is the first in the Gulf Coast to use air injection successfully in a high-permeability, light-oil reservoir.
Two reservoirs are currently undergoing air injection, which can be less costly than carbon dioxide injection, and can be used in areas where carbon dioxide is not available. The first reservoir already has more than doubled its oil production rate from 180 to 370 barrels per day.
A similar increase is expected in the additional reservoirs within the oil field. The project is expected to yield over 3 million barrels of incremental oil.
Gas-Miscible & -Immiscible Recovery:
Miscible Gas Drive: In place of the costly hydrocarbon gases used in the past, miscible gas drives now inject such gases as carbon dioxide, nitrogen, or flue gas.
Along with steam flooding, carbon dioxide flooding has proven to be among the most promising EOR methods for the U.S. because it takes advantage of plentiful, naturally-occurring carbon dioxide. Incremental production cost for carbon dioxide flooding is estimated at $2 to $8 per barrel.
An example of a DOE-sponsored project in this area is an effort with New Mexico Institute of Mining and Technology and Stanford University. The two universities have teamed to conduct laboratory and field-based research to better understand physical phenomena associated with miscible and immiscible gas displacement, especially carbon dioxide.
Of the available suite of advanced oil recovery methods, gas injection presently has the greatest potential for additional oil recovery from U.S. light oil reservoirs. Gas injection, particularly miscible or near-miscible flooding, has been applied to relatively homogeneous reservoirs.
Efforts are aimed at further exploration of the applicability of selective mobility reduction in the use of foam flooding; improving the effectiveness of carbon dioxide flooding in heterogeneous reservoirs; demonstrating how gas injection can be applied to heterogeneous reservoirs; and investigating new concepts that can be applied by field operators within the next two to five years.
New concepts that are being considered have the potential of recovering oil believed to be unrecoverable.
To date, New Mexico Tech research has shown good results for low permeability reservoirs, such as the Permian basin Sprayberry, which has more than 6 billion barrels of remaining oil.
Several oil companies have acquired Stanford University's new super-high-speed computing techniques that significantly reduce cost of reservoir simulation.
Source: United States Department of Energy
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