Carbon dioxide flooding
Encyclopedia
Carbon dioxide flooding is a process whereby carbon dioxide
is injected into an oil reservoir in order to increase output when extracting oil.
When a reservoir’s
pressure is depleted through primary and secondary production, Carbon Dioxide flooding can be an ideal tertiary recovery method. It is particularly effective in reservoirs deeper than 2,000 ft., where will be in a supercritical
state, with API oil gravity
greater than 22–25º and remaining oil saturations greater than 20%. It should also be noted that Carbon dioxide flooding is not affected by the lithology
of the reservoir area but simply by the reservoir characteristics.
Carbon dioxide flooding works on the premise that by injecting CO2 into the reservoir, the viscosity
of any hydrocarbon
will be reduced and hence will be easier to sweep to the production well.
If a well has been produced before and has been designated suitable for CO2 flooding, the first thing to do is to restore the pressure
within the reservoir to one suitable for production. This is done by injecting water (with the production well shut off) which will restore pressure within the reservoir to a suitable pressure for CO2 flooding. Once the reservoir is at this pressure, the next step is to inject the CO2 into the same injection wells used to restore pressure. The CO2 gas is forced into the reservoir and is required to come into contact with the oil. This creates this miscible zone that can be moved easier to the production well. Normally the CO2 injection is alternated with more water injection and the water acts to sweep the oil towards the production zone. The Weyburn oil field is a famous example where this method is applied in financially interesting conditions.
CO2 flooding is the second most common tertiary recovery technique and is used in facilities around the world. In the scope of global warming
, it is an available method to curb CO2 emissions.
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
is injected into an oil reservoir in order to increase output when extracting oil.
Oil reserves
The total estimated amount of oil in an oil reservoir, including both producible and non-producible oil, is called oil in place. However, because of reservoir characteristics and limitations in petroleum extraction technologies, only a fraction of this oil can be brought to the surface, and it is...
pressure is depleted through primary and secondary production, Carbon Dioxide flooding can be an ideal tertiary recovery method. It is particularly effective in reservoirs deeper than 2,000 ft., where will be in a supercritical
Supercritical fluid
A supercritical fluid is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist. It can effuse through solids like a gas, and dissolve materials like a liquid...
state, with API oil gravity
API gravity
The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks...
greater than 22–25º and remaining oil saturations greater than 20%. It should also be noted that Carbon dioxide flooding is not affected by the lithology
Lithology
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of...
of the reservoir area but simply by the reservoir characteristics.
Carbon dioxide flooding works on the premise that by injecting CO2 into the reservoir, the viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
of any hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
will be reduced and hence will be easier to sweep to the production well.
If a well has been produced before and has been designated suitable for CO2 flooding, the first thing to do is to restore the pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
within the reservoir to one suitable for production. This is done by injecting water (with the production well shut off) which will restore pressure within the reservoir to a suitable pressure for CO2 flooding. Once the reservoir is at this pressure, the next step is to inject the CO2 into the same injection wells used to restore pressure. The CO2 gas is forced into the reservoir and is required to come into contact with the oil. This creates this miscible zone that can be moved easier to the production well. Normally the CO2 injection is alternated with more water injection and the water acts to sweep the oil towards the production zone. The Weyburn oil field is a famous example where this method is applied in financially interesting conditions.
CO2 flooding is the second most common tertiary recovery technique and is used in facilities around the world. In the scope of global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
, it is an available method to curb CO2 emissions.
External links
- Mississippi Oil Journal Map Oil Well Map of EOR field in Brookhaven Mississippi
- Enhanced Oil Recovery Institute Enhanced Oil Recovery Institute