Gas lift
Gas lift or bubble pumps use the artificial lift technique of raising a fluid such as water or oil by introducing bubbles of compressed air, water vapor or other vaporous bubbles into the outlet tube. This has the effect of reducing the hydrostatic pressure in the outlet tube vs. the hy…
How do gas lifts work?
Gas lifts use the artificial lift method by injecting gas into the production tubing to raise water or oil. The gas injected is high-pressure gas by adding bubbles of compressed air and vapor. This acts to lower the hydrostatic pressure at the bottom of the tubing, reducing its density.
What is the difference between gas lift and artificial lift?
A lower bottomhole flowing pressure and higher flow rate can be achieved with gas lift in which the density of the fluid in the tubing is lowered and expanding gas helps to lift the fluids. Artificial lift can be used to generate flow from a well in which no flow is occurring or used to increase the flow from a well to produce at a higher rate.
Why do oil and gas wells need artificial lift?
Most oil wells require artificial lift at some point in the life of the field, and many gas wells benefit from artificial lift to take liquids off the formation so gas can flow at a higher rate. The major forms of artificial lift are:
What is the working principle of artificial lift system?
The working principle of an artificial lift system is to maintain the required bottom hole pressure by artificial means to produce desired fluids.
What is artificial lift method?
Artificial lift is a method used to lower the producing bottomhole pressure (BHP) on the formation to obtain a higher production rate from the well. This can be done with a positive-displacement downhole pump, such as a beam pump or a progressive cavity pump (PCP), to lower the flowing pressure at the pump intake.
Which gas is used in gas lift?
Gas lift or bubble pumps use the artificial lift technique of raising a fluid such as water or oil by introducing bubbles of compressed air, water vapor or other vaporous bubbles into the outlet tube.
What is the difference between gas injection and gas lift?
Although the terms are sometimes interchanged, gas injection and gas lift are two separate processes that are used to increase production. While gas injection is a secondary production method, gas lift is a type of artificial lift.
Which artificial lift gives us more efficiency?
The most excellent device available for artificial lifting is the PCP pump, which can be more than 70% efficient in converting mechanical energy to hydraulic work.
What is lift gas used for?
Gas lift is a method of artificial lift that uses an external source of high-pressure gas for supplementing formation gas to lift the well fluids. The principle of gas lift is that gas injected into the tubing reduces the density of the fluids in the tubing, and the bubbles have a “scrubbing” action on the liquids.
Why is gas-lift used?
Gas lifts use the artificial lift method by injecting gas into the production tubing to raise water or oil. The gas injected is high-pressure gas by adding bubbles of compressed air and vapor. This acts to lower the hydrostatic pressure at the bottom of the tubing, reducing its density.
Is nitrogen gas heavier than air?
Nitrogen gas is only slightly lighter than air and readily mixes with air at room temperature. Cold vapors are more dense and will settle. Liquid nitrogen, a cryogenic liquid, has a very low boil- ing point of –320°F.
Which is the lightest gas?
HydrogenHydrogen: Hydrogen is the lightest gas present abundantly in the universe with an atomic mass of. 00784 u . It is one of the most reactive gases and it is also the most abundant gas in the universe.
What is gas lift?
Gas lift is a method of artificial lift that uses an external source of high-pressure gas for supplementing formation gas to lift the well fluids. The principle of gas lift is that gas injected into the tubing reduces the density of the fluids in the tubing, and the bubbles have a “scrubbing” action on the liquids.
How is a gas lift well produced?
The vast majority of gas lift wells are produced by continuous flow, which is very similar to natural flow. Fig. 1 shows a schematic of a gas-lift system. In continuous-flow gas lift, the formation gas is supplemented with additional high-pressure gas from an outside source. Gas is injected continuously into the production conduit at a maximum depth that depends upon the injection-gas pressure and well depth. The injection gas mixes with the produced well fluid and decreases the density and, subsequently, the flowing pressure gradient of the mixture from the point of gas injection to the surface. The decreased flowing pressure gradient reduces the flowing bottomhole pressure below the static bottomhole pressure thereby creating a pressure differential that allows the fluid to flow into the wellbore. Fig. 2 illustrates this principal.
What are the limitations of gas lift?
The primary limitation for gas lift operations is the lack of formation gas or an injection-gas source. Wide well spacing and lack of space for compressors on offshore platforms may also limit the application of gas lift. Poor compressor maintenance can increase compressor downtime and add to the cost of gas lift gas, especially with small field units. Compressors are expensive and must be properly maintained. Generally, gas lift is not as suitable as some other systems for single-well installations and widely spaced wells. The use of wet gas without dehydration reduces the reliability of gas lift operations.
What is a gas compressor?
Gas compressors are nearly always installed to gather the produced gas and , with only minor changes, can be designed to supply the high injection-gas pressure for the gas lift system. The injected gas only supplements the formation gas and may amount to only a small percentage of the total produced-gas volume.
Why is it so hard to lift crude oil?
There is increased difficulty when lifting low gravity (less than 15°API) crude because of greater friction, gas fingering, and liquid fallback. The cooling effect of gas expansion may further aggravate this problem. Also, the cooling effect will compound any paraffin problem.
Why use a central gas lift system?
In some cases, switching to annular flow also can be easily accomplished to handle exceedingly high volumes. A central gas-lift system easily can be used to service many wells or operate an entire field. Centralization usually lowers total capital cost and permits easier well control and testing.
Is intermittent flow gas lift continuous?
Because of the intermittent production of the well, intermittent-flow gas lift is not capable of producing at as high a rate as continuous-flow gas lift. Intermittent flow should not be considered unless the flowing bottomhole pressure is low, and the well is gas lifting from the bottom valve.
What is Artificial Lift?
Artificial lift is a process to increase the fluid flow by artificial means. The artificial lift method is used to withdraw crude oil from production wells by increasing pressure within the reservoir.
Working of an Artificial Lift
The working principle of an artificial lift system is to maintain the required bottom hole pressure by artificial means to produce desired fluids.
Artificial Lift Methods
There are several artificial lift methods in the oilfield industry. However, the most widely used common methods for artificial lifts are:
Selection of Artificial Lift system
The selection of an artificial lift method depends on various parameters like:
How does a gas lift work?
To employ gas lift, a producer sends low-pressure gas from the well through a compressor. They then send it back down the well. This pressurizes the well and forces liquids back up to the surface piping and equipment.
What is artificial lift in oilfields?
What is Artificial Lift in the oilfield? Artificial lift describes a variety of methods oil and gas producers use to increase downhole pressure and push resources up to the surface.
How does a pump jack work?
The pump jack uses sucker rod string and pump to pressurize the well downhole and bring resources up to the surface piping and equipment. The rods don't rotate. They go inside the tubing, which is inside casing. At the bottom of the rod string is a pump and two check valves. A pump jack may be powered by electricity or gas.
What is the best artificial lift?
Plunger lift is a great option for artificial lift. It's often the first form of artificial lift producers use because they can install it without the large expense of a work-over rig. It's more cost effective than PCP and rod lift, can be set up in a day, requires few people, and doesn't change a lot on location.
What is a plunger lift?
Plunger lift can be used to create a pressure differential and draw liquid up the casing to production equipment. This type of artificial lift is done through the use of a timer control, which is typically connected to a High Pressure Control Valve. There are several different types of plungers, including a solid plunger, pad plunger, ...
How many barrels of gas can be lifted in a day?
Gas lift can production ranges widely, from hundreds to several thousand barrels of fluid per day.
What is the most common type of lift?
In some areas like the DJ Basin in Colorado, many producers even start new wells with artificial lift to get production flowing strong from the beginning. Some of the most common types of artificial lift are Progressive Cavity Pump (PCP), Rod Lift, Plunger Lift, Gas Lift, Hydraulic Lift, and Electric Submersible Pump (ESP).
How does a gas lift work?
Gas lifts use the artificial lift method by injecting gas into the production tubing to raise water or oil. The gas injected is high-pressure gas by adding bubbles of compressed air and vapor. This acts to lower the hydrostatic pressure at the bottom of the tubing, reducing its density. The injected gas is normally injected down ...
When was the gas lift used?
For the oil & gas industry, the gas lift was used in Pennsylvania to help production in oil wells in 1864. The compressed air being used was an air pipe ...
How does gas enter the production tube?
The injected gas is normally injected down the tubing annulus and enters the production tube through multiple gas lift valves. The fluid is then forced up and out of the wellbore. This process allows the fluids to begin flowing when they can no longer flow on their own.
When injecting gas downhole, it could be injected continuously or intermittently?
This depends on the way the gas lift equipment is arranged and producing characteristics. Deciding just how much gas needs to be injected depends on the well conditions and geometries.
What happens if you inject too much gas?
If too much gas is injected, the economics may not be sound but if too little, then production may not be maximized . For the gas to be at the appropriate pressure to be re-injected, the process requires a compressor which will raise the pressure of the gas to the appropriate levels of re-injection.
What is compressed air used for?
Fun Fact: This method of using compressed air to lift fluids is used in other applications such as dredging, underwater archaeology, and used to in aquariums to help keep the water circulating. Interesting what you can learn from other applications and how you can apply it to the task at hand!
How does artificial lift work?
Artificial lift is a method used to lower the producing bottomhole pressure (BHP) on the formation to obtain a higher production rate from the well . This can be done with a positive-displacement downhole pump, such as a beam pump or a progressive cavity pump (PCP), to lower the flowing pressure at the pump intake. It also can be done with a downhole centrifugal pump, which could be a part of an electrical submersible pump (ESP) system. A lower bottomhole flowing pressure and higher flow rate can be achieved with gas lift in which the density of the fluid in the tubing is lowered and expanding gas helps to lift the fluids. Artificial lift can be used to generate flow from a well in which no flow is occurring or used to increase the flow from a well to produce at a higher rate. Most oil wells require artificial lift at some point in the life of the field, and many gas wells benefit from artificial lift to take liquids off the formation so gas can flow at a higher rate.
Why do oil wells need artificial lift?
Most oil wells require artificial lift at some point in the life of the field, and many gas wells benefit from artificial lift to take liquids off the formation so gas can flow at a higher rate .
What factors are considered when selecting an artificial lift system?
Among the most important factors to consider when selecting an artificial lift system are current and future reservoir pressure and well productivity. If producing oil or liquid rate is plotted (X axis) against producing bottomhole pressure (BHP) [Y axis], one of two inflow performance relationships (IPR) usually is seen. Above the bubblepoint pressure, the liquid rate vs. pressure drop below the reservoir pressure (drawdown) is linear. Below the bubblepoint pressure, a relationship similar to that described by Vogel occurs. Fig. 1 illustrates production vs. drawdown relationships as a single IPR with a bubblepoint of 750 psig and an average reservoir pressure of 2,000 psig. If the necessary data are available, a single-phase IPR expression for either gas or liquid flow is available from radial-flow equations. Gas deliverability curves show a nonlinear dependence of gas rate similar to the liquid rate vs. pressure on a Vogel curve. Liquid-rate IPR curves can have a gas-to-liquid ratio associated with the liquid rate, and gas deliverability curves can have a liquid production (e.g., bbl/MMscf/D) associated with the gas rates. Our discussion will focus on IPRs with liquid production as a function of the flowing BHP.
Can a plunger lift cause wear?
Sand- or solids-laden production, which can rule out the use of plunger lift, can also cause wear with sucker-rod pumps, reciprocating hydraulic pumps, and jet pumps. Gas lift and PCPs produce moderate volumes of solids with only minor problems. The producing gas/liquid ratio is very important to the lift designer.
Is gas interference a detriment?
If the percentage of free gas at intake conditions is high, gas interference is a potential detriment to all methods of lift, but it is a benefit to gas lift. High-fluid viscosity hinders most major forms of lift, but the PCP may produce low temperature, shallow, viscous fluids with little difficulty.
Can a downhole pump be used as an ESP?
It also can be done with a downhole centrifugal pump, which could be a part of an electrical submersible pump (ESP) system. A lower bottomhole flowing pressure and higher flow rate can be achieved with gas lift in which the density of the fluid in the tubing is lowered and expanding gas helps to lift the fluids.
Continuous-Flow Gas Lift
- The vast majority of gas lift wells are produced by continuous flow, which is very similar to natural flow. Fig. 1 shows a schematic of a gas-lift system. In continuous-flow gas lift, the formation gas is supplemented with additional high-pressure gas from an outside source. Gas is injected continuously into the production conduit at a maximum depth that depends upon the injection-g…
Intermittent-Flow Gas Lift
- As the name implies, intermittent flow is the periodic displacement of liquid from the tubing by the injection of high-pressure gas. The action is similar to that observed when a bullet is fired from a gun. (See Fig. 2.) The liquid slug that has accumulated in the tubing represents the bullet. When the trigger is pulled (gas lift valve opens), high-pressure injection gas enters the chamber (tubing…
Applications
- Gas lift is particularly applicable for lifting fluids in wells that have a significant amount of gas produced with the crude. Gas compressors are nearly always installed to gather the produced gas and, with only minor changes, can be designed to supply the high injection-gas pressure for the gas lift system. The injected gas only supplements the f...
Limitations of Gas Lift
- The primary limitation for gas lift operations is the lack of formation gas or an injection-gas source. Wide well spacing and lack of space for compressors on offshore platforms may also limit the application of gas lift. Poor compressor maintenance can increase compressor downtime and add to the cost of gas lift gas, especially with small field units. Compressors are …
Noteworthy Papers in OnePetro
- Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
External Links
- Yadua, A.U., Lawal, K.A., Eyitayo, S.I. et al. Performance of a gas-lifted oil production well at steady state. J Petrol Explor Prod Technol (2021). https://link.springer.com/article/10.1007/s13202-021-01188-0