Let's learn About Oil Production: Artificial Lift Systems
Updated: Jul 22
Every oil producer's aim is to extract as much oil as possible from their wells. Artificial lift systems are pivotal in enhancing the efficiency and productivity of oil production. From deep wells to mature fields, Electric Submersible Pumps (ESPs) and Gas Lift Systems are used to boost initial production in new wells and increase production from old wells.
Why Do We Need Artificial Lifts?
When a well is first drilled, oil often flows to the surface naturally because of underground pressure. As time passes, the reservoir pressures drop, making it harder for oil to reach the surface through natural flow. This is when the artificial lift comes into play – to “lift” the oil up from deep underground to the surface.
However, it is not uncommon for artificial lift systems to be used right from the start. This may be because some wells do not contain enough pressure within the reservoir to push oil to the surface without simulation[1], or it may be simply because operators want to boost initial production to achieve production targets and more profitability.
Artificial lift methods are deployed across onshore and offshore operations, taking into consideration factors such as reservoir characteristics, well depth, fluid composition and economic considerations.
Among the most widely used methods are ESPs and Gas Lift Systems; the applications, mechanisms and advantages of each vary significantly.
What are ESPs?[2]
The ESPs consist of a multi-stage centrifugal pump that is installed deep within the wellbore and is connected to a high-powered electric motor. As the motor drives the pump, the impellers on the pump spin and draw fluid through the intake, building pressure to lift the fluid to the surface.
ESPs are highly effective for high-volume wells due to their ability to handle high flow rates of more than 25,000 barrels of fluids per day. They are robustly designed to withstand high pressures and temperatures in deep wells of up to 12,000 feet.
The complex systems rely on intensive electrical infrastructure and downhole sensors for real-time monitoring. Due to the harsh downhole environment, ESPs are prone to wear and tear and often require regular maintenance which can be costly and time-consuming as retrievals and replacement require workovers or rig intervention. The initial capital investment for the ESP is also relatively high, given the complexity of the equipment and installation process.[3]
Nevertheless, ESPs are highly adaptable in their ability to handle various fluid types, including those with gas or moderate solids content; and to operate in corrosive environments. With their compact design, ESPs are ideal for offshore operations where space and weight are key considerations.[4]
What are Gas Lift Systems?
Gas lift systems involve injecting compressed gas into the wellbore to reduce the density of the fluid column. Gas lift valves are strategically placed along the tubing to inject gas at specific depths, helping to control and regulate gas flow. This reduction in fluid density allows the reservoir pressure to push the fluids more easily to the surface through the production tubing.[5]
This system is highly versatile and well-suited for various conditions and changing reservoir environments, especially for wells with higher gas-to-oil ratios, or with horizontal or deviated well paths. Compared to the ESP, gas lift can be a more cost-effective solution, especially at offshore settings where gas infrastructure is already present.
As most components are located above ground, there is minimal downtime for the initial installation, making operations more accessible. With few moving parts, maintenance and repairs are less invasive and can often be made at the surface without pulling the tubing.[6] As such, the gas lift is well suited for mature fields that may require frequent adjustments.
ESPs or Gas Lift?
The choice between ESPs and gas lift systems depends on many factors – from well depth and fluid composition to infrastructure availability and long-term maintenance considerations. The key is selecting the right method for the right well.
[1] Rigzone, How Does Artificial Lift Work?
[2] Intrinsically Safe Store, ESP Technology in the Petroleum Sector: An Overview
[3] 4 January 2022, Estis Compression, How to Compare Artificial Lift Options for Unconventional Oil Production
[4] 1 August 2024, Windings Inc, Exploring Artificial Lift and Electric Motors in Oil and Gas
[6] Petroleum Training Partners, A Deep Dive into Gas Lift Valves and Mandrels | Benefits, Types, Importance 2024
