In the oil and gas sector, enhanced oil recovery, or EOR, is an innovative technique that is revolutionizing oil extraction. It uses a series of cutting-edge processes intended to extract more oil from subterranean sources that are challenging to access using conventional techniques.

Think of it as providing oil fields that could otherwise be viewed as less productive or perhaps abandoned as a second opportunity. We'll explore the various advantages of EOR, its operation, and how it helps the oil and gas industry have a more sustainable future in this blog.

The capacity of EOR to greatly boost oil production while simultaneously increasing efficiency is what really sets it apart. EOR contributes to waste reduction, resource optimization, and even industrial sustainability initiatives by employing creative techniques.

This implies that acquiring more oil is not the only goal; doing so in a more intelligent and environmentally friendly manner is equally important. Let's start with the types of oil recovery.

Types of Oil Recovery

The process of extracting as much oil and gas as possible from a reservoir that contains hydrocarbons is known as oil recovery in hydrocarbon production. The production rate usually fluctuates throughout a well's existence. To ensure that production quantities stay at sustainable levels for as long as possible, the formation will need more stimulation.

Depending on the well's age, formation properties, and operating costs, a variety of methods and technologies are used in multiple stages to get the best possible oil recovery.

Let's now study the various methods of oil recovery.

Primary Oil Recovery

When oil is first being produced, primary recovery is used. It starts as soon as drilling operations are finished for traditional oil and gas. At the wellhead, a Christmas tree (oil well) is then placed. The reservoir's natural formation pressure and simple pumping operations through the production casing are the main causes of oil production in primary recovery. However, only around 30% of OIIP is recovered using basic oil recovery techniques.

Secondary Oil Recovery

Primary recovery is followed by secondary recovery, usually as a result of a drop in the reservoir's normal formation pressure. To push additional oil into the production casing, the operator can use an injection well to flood the reservoir with gas or steam. Up to 60% of OIIP can be recovered by operators with the aid of secondary oil recovery techniques.

Tertiary Recovery/Enhanced Oil Recovery

In brownfields and unconventional oil and gas plays around the United States, tertiary oil recovery techniques are widely used to enable operators to recover up to 75% of the oil initially in place (OIIP). As a result, current productivity has increased by as much as 300%!

These are three main types of oil recovery. Once any oil or gas well has undergone primary and secondary recovery methods, the well is then chosen for enhanced oil recovery.

What is (EOR) Enhanced Oil Recovery?

The process of obtaining oil that hasn't been recovered using primary or secondary oil recovery techniques is called enhanced oil recovery (EOR), or "tertiary recovery."

Enhanced oil recovery works by changing the chemical makeup of the oil itself to make it easier to remove, while primary and secondary recovery methods depend on the pressure differential between the surface and the underground well.

Here are some essential takeaways of EOR

The process of extracting oil from a well that has already undergone the main and secondary stages of oil recovery is known as enhanced oil recovery, or EOR.
EOR methods might not be profitable depending on the price of oil.
Although new developments in the industry may assist lessen this impact in the future, EOR procedures can have a detrimental environmental impact.

How Does Enhanced Oil Recovery Work?

When secondary recovery procedures are not enough to maintain profitable production, enhanced recovery methods are used for natural gas and oil. This is generally caused by unconventional oil and gas plays like tight sandstone or shale or by a significant decline in reservoir pressure.

As enhanced oil recovery methods are costly and complicated, they are only used when primary and secondary recovery methods fail to recover all the hydrocarbons. In fact, it could not be cost-effective to use EOR at all, depending on variables like oil prices. When it is simply not profitable to remove the remaining volumes, oil and gas may be left in the reservoir in those situations.

Chemical injection, steam injection, and gas injection are the three main enhanced oil recovery methods. Usually, non-standard enhanced oil recovery technology is needed for these techniques.

Gas Injection

In unconventional reservoirs and mature wells, gas injection, an EOR technique, uses carbon dioxide (CO2) or nitrogen gas (N2) to displace crude oil in a miscible manner. Recovery works on the basis that the gas's dissolution in the oil lowers its viscosity, increasing mobility. Nearly 60% of EOR production in the US is attributed to gas injection techniques, according to the US Department of Energy.

CO2 is pumped into the formation through injection wells in order to execute a gas injection successfully. The gas creates a miscible zone at high downhole pressures, which collects stranded oil and pushes it in the direction of the target well's production casing. To further enhance sweep efficiency, gas injection and water injection are frequently switched utilizing a water injection pump system.

Operators may choose to employ high-purity nitrogen gas as a result of increased concerns about the effects of CO2, a recognized greenhouse gas, on global climate change. N2 is generally preferable to CO2 due to its comparatively inert characteristics, which inhibit downhole combustion. Additionally, a nitrogen generator skid can be used to economically produce N2 from atmospheric air.

Steam Injection

In order to remove stranded oil from a reservoir after a drop in formation pressure, steam injection improves oil recovery—also known as thermal recovery or steam flooding—involves injecting water vapor into a well at high temperatures and pressures.

An operator drills one or more "injection" wells near the well for stimulation in order to perform steam injection. The injection well or wells are then used to introduce steam into the formation. It improves mobility toward the production casing by lowering the oil's viscosity and raising its kinetic energy upon contact. In thick oil reservoirs, steam injection is especially helpful for oil recovery. Additionally, more than 40% of EOR production in the US, mostly in California, is produced via steam injection techniques.

Chemical Injection

To release oil and gas molecules from far-flung areas of the reservoir, chemical injection involves injecting long-chain polymers into a well using a chemical injection skid. Waterflooding can be combined with chemical injection. By boosting the effectiveness of the surfactants for better hydrocarbon mobility, this successfully raises the recovery factor.

By lowering the interfacial tension between the hydrocarbon molecules and the water in the reservoir, the polymers used in this EOR process—which can be alkaline or micellar—improve the flow of crude (sweep efficiency).

Co2 Injection

Co2 injection is another useful technique in addition to these three forms of increased oil recovery. The carbon sequestration process, also known as C02 sequestration, uses CO2 pumps and injection pumps. In order to manage the corrosion, scaling, and possibly greater temperatures that come with re-injection, this injection technique is essential.

For CO2 pumping and injection, AP-610 pumps are especially efficient, and a complete range of pumps is offered to satisfy the Carbon Capture, Utilization, and Storage (CCUS) requirements.

Here are few types of pumps that can be considered:

Process Pump
Pumps that are in line
Vertical Pumps
Double-stage single-stage pumps
Pumps with split cases
Pumps with barrels
Packaged Systems

By the above methods, enhanced oil recovery is executed. EOR recovers all the remaining oil from the reservoir, offering numerous benefits.

Benefits of Enhanced Oil Recovery

Enhanced oil recovery (EOR) has many benefits, including:

A Rise in the Production of Oil

EOR can extract more oil from older fields that are inaccessible to traditional techniques.

Storage of Carbon Dioxide

EOR can help reduce greenhouse gas emissions by permanently storing carbon dioxide (CO2) underground.

Security of Energy

EOR has the potential to increase employment in the oil and gas sector and lessen the US's need for oil imports.

Cost-Efficiency

Particularly in established fields, EOR may be less expensive than drilling new wells.

Longer Lifespan for Production

EOR can maximize resource usage by extending the life of oil fields.

Increased Oil Mobility

EOR can enhance an oil's flow properties, which will facilitate extraction.

Conclusion

When primary and secondary procedures are no longer successful, EOR is a sophisticated process used to recover more oil from reservoirs. It increases output, prolongs oil field life, and, by storing CO2, can help with sustainability initiatives.

In order to increase oil mobility and recovery efficiency, three essential techniques are gas injection, steam injection, and chemical injection. EOR is expensive and complicated, but with the right innovation, it can improve energy security, optimize resource use, and benefit the environment.