The Basics Of Enhanced Oil Recovery (EOR) and EOR Technologies

Mar 15, 2022 | Blog

What is Enhanced oil recovery (EOR)

Primary, secondary, and tertiary oil production (also known as Enhanced Oil Recovery) are the three stages of oil production (EOR). Only hydrocarbons that naturally rise to the surface or those requiring artificial lift devices like pump jacks are suitable for primary oil recovery. Water and gas injection is used in secondary recovery to displace the oil and drive it to the surface. These two production techniques can leave up to 75% of the oil in the well.

The tertiary recovery method, often known as EOR, is a strategy to boost oil production even more. EOR can enhance output from a well to up to 75 per cent recovery, despite being more expensive to implement on a field.

EOR is used in fields with heavy oil, poor permeability, and uneven faultlines, and it involves modifying the hydrocarbons’ fundamental characteristics, which sets it apart from secondary recovery. While the secondary recovery method uses waterflooding and gas injection to force the oil down the well, EOR uses steam or gas to modify the makeup of the reservoir.

EOR restores formation pressure and increases oil displacement in the reservoir. It is utilised after both primary and secondary recovery have been depleted or at the very start of production.

Enhanced oil recovery technologies

Chemical flooding, gas injection, and thermal recovery are the three basic forms of EOR. Producers do not use EOR on all wells and reservoirs because it increases the expense of development along with the hydrocarbons delivered to the surface. The development equation’s economics must make sense. As a result, each field must be thoroughly assessed to decide which type of EOR will be most effective in the reservoir. Reservoir characterisation, screening, scoping, and reservoir modelling and simulation are all used to accomplish this.

Thermal Recovery

Thermal recovery involves injecting the heat into the reservoir to lessen the oil’s viscosity. Steam is frequently injected into the reservoir to thin the oil and improve its flowability. Thermal recovery, first used in Venezuela in the 1960s, today accounts for more than half of all applied EOR in the United States.

Chemical Injection

Injection of a chemical EOR aids in releasing trapped oil from a reservoir. This method delivers long-chained molecules known as polymers into the reservoir to improve waterflooding efficiency or the effectiveness of surfactants. Surfactants are cleaners that help lower surface tension, preventing oil from flowing through the reservoir. Chemical injections account for less than 1% of all EOR procedures now used in the United States.

Gas Injection

The tertiary recovery method, gas injection, involves pumping natural gas, nitrogen, or carbon dioxide into the reservoir. The gases can expand and push gas through the reservoir, or they can mix with or dissolve in the oil, lowering viscosity and improving flow.

CO2 Enhanced oil recovery

The technology gaining the most traction is carbon dioxide EOR (CO2-EOR). While the first CO2-EOR projects relied on naturally occurring carbon dioxide reserves, new technologies have been developed to inject CO2 produced as a byproduct of industrial processes.

CO2-EOR was first utilised in the United States in the early 1970s in Texas, and it is currently being used successfully in Texas and New Mexico. It is projected to become more widely used in the future. Gas injection accounts for about half of all EOR in the United States.

Two more EOR applications that are gaining acceptance are Low-salinity water flooding and well stimulation. Low-salinity water flooding is predicted to improve production by about 20%, while well stimulation is a relatively low-cost option because it can be used on single wells (rather than the whole reservoir).

Offshore EOR Applications

Even though EOR applications are primarily used onshore, solutions are being developed to extend EOR’s reach to offshore applications. The economics of offshore EOR is currently being challenged, as are the weight, space, and power limits of retrofitting existing offshore facilities, as well as fewer wells that are more widely spread, all of which contribute to displacement, sweep, and lag time.

The use of EOR is currently being studied for many offshore projects. With successful subsea processing and secondary recovery methods such as water and gas injection being used in offshore locations, the technology to apply EOR procedures is rapidly approaching.

EOR In Canada and the US

With EOR technology, additional stranded oil in Canada and the United States might be retrieved, reducing both countries’ reliance on foreign oil, an initiative for which the United States has been striving. More extensive deployment of EOR technology on North American reservoirs, on the other hand, would necessitate a significantly greater cost of production, and the price of oil would have to justify the investment.

Final thoughts

Orion Projects has expertise in the area of Carbon Capture, compression and sequestration, and Enhanced Oil Recovery to support small to large scale projects.