Enhanced Oil Recovery

Key Takeaways

• Enhanced oil recovery (EOR) is the process of extracting remaining oil from a well after primary and secondary recovery methods are used.
• There are three main types of EOR: gas injection, thermal recovery, and chemical injection, each with different processes and applications.
• EOR is often more costly and complex than typical recovery methods, due to its dependence on altering oil properties and reservoir conditions.
• Environmental concerns exist with EOR, especially regarding CO2 emissions, but new technologies like plasma pulsing may reduce negative impacts.
• EOR can extend the life of oil fields and maximize output from proven reserves but remains sensitive to oil price fluctuations.

What Is Enhanced Oil Recovery (EOR)?

Enhanced oil recovery (EOR) is a technique used in the oil extraction process aimed at retrieving additional oil from wells after primary and secondary methods have been exhausted. EOR is important in increasing oil production efficiency and its potential economic impacts, particularly when oil prices are favorable. It involves altering the chemical composition or physical properties of the oil to make it easier to extract, using methods like gas injection, steam injection, and chemical injection.

We'll cover various EOR techniques, their applications, and their potential environmental implications, and give you some examples of its application.

How Enhanced Oil Recovery Works

Enhanced oil recovery techniques are complex and expensive and therefore are employed only when the primary and secondary recovery techniques have exhausted their usefulness. Indeed, depending on factors such as the cost of oil, it may not be economical to employ EOR at all. In those cases, oil and gas might be left in the reservoir because it is simply not profitable to extract the remaining amounts.

The Top EOR Techniques

In the first type of technique, gases are forcefully injected into the well in a way that both forces the oil to the surface and reduces its viscosity. The less viscous the oil, the easier it flows and the more cheaply it can be extracted. Although various gases can be used in this process, carbon dioxide (CO2) is used most often.

This specific use of carbon dioxide likely could continue or even increase in the future, as recent advances make it possible to transport CO2 in the form of foams and gels. To some, this could be a significant improvement as it would allow CO2 injections to be utilized in areas far removed from naturally occurring carbon dioxide reservoirs.

Important

On the other hand, there are grave concerns about the continued use of carbon dioxide because of its harmful effects on the environment. Currently, most countries are seeking alternative modes of energy that are more sustainable than CO2.

Other common EOR techniques include pumping steam into the well in order to heat the oil and make it less viscous. Similar outcomes can be achieved through so-called “fire flooding,” which involves lighting a fire around the periphery of the oil reservoir in order to drive the remaining oil close to the well.

Finally, various polymers and other chemical structures can be injected into the reservoir to reduce viscosity and increase pressure, although these techniques are often prohibitively expensive.

Applications of Enhanced Oil Recovery Methods

Petroleum companies and scientists look to EOR for its potential to prolong the life of wells in proven or probable oil fields. Proven reserves are those with a greater than 90% chance that oil will be recovered, and probable reserves have a more than 50% chance of recovering petroleum.

Unfortunately, EOR techniques can produce negative environmental side effects, such as causing harmful chemicals to leak into the groundwater. One recent technique that might help reduce these environmental risks is called plasma pulsing. Developed in Russia, plasma pulse technology involves radiating oil fields with low-energy emissions, thereby lowering their viscosity much like conventional EOR techniques.

Because plasma pulsing does not require injecting gases, chemicals, or heat into the ground, it may prove to be less environmentally harmful than the other current methods of oil recovery.

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