A gas lift or bubble pump is a type of

pump A pump is a device that moves fluids (liquids or gases), or sometimes Slurry, slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of application ...

that can raise fluid between elevations by introducing

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

bubbles Bubble, Bubbles or The Bubble may refer to: Common uses * Bubble (physics), a globule of one substance in another, usually gas in a liquid ** Soap bubble * Economic bubble, a situation where asset prices are much higher than underlying fundame ...

into a vertical outlet tube; as the bubbles rise within the tube they cause a drop in the

hydrostatic pressure Hydrostatics is the branch of fluid mechanics that studies fluids at hydrostatic equilibrium and "the pressure in a fluid or exerted by a fluid on an immersed body". The word "hydrostatics" is sometimes used to refer specifically to water and o ...

behind them, causing the fluid to be pulled up. Gas lifts are commonly used as artificial lifts for water or

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

, using

compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air in vehicle tires and shock absorbers are commonly used for improved traction and reduced vibration. Compressed air is an important medium for t ...

water vapor Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...

. Gas lifts have been used for a variety of applications: *

Coffee percolator A coffee percolator is a type of pot used for the brewing of coffee by continually cycling the boiling or nearly boiling brew through the grounds (coffee), grounds using gravity until the required strength is reached. The grounds are held in a ...

s and electric drip coffeemakers use vaporized water to lift hot water *

Airlift pump An airlift pump is a pump that has low suction and moderate discharge of liquid and entrained solids. The pump injects compressed air at the bottom of the discharge pipe which is immersed in the liquid. The compressed air mixes with the liquid c ...

s use compressed air to lift water *

Pulser pump A pulser pump is a gas lift device that uses gravity to pump water to a higher elevation. It has no moving parts. Operation A pulser pump makes use of water that flows through pipes and an air chamber from an upper reservoir to a lower reservoir ...

s use a subterranean air chamber to lift underground water * Suction dredges use a variety of the gas lift called an ''

airlift pump An airlift pump is a pump that has low suction and moderate discharge of liquid and entrained solids. The pump injects compressed air at the bottom of the discharge pipe which is immersed in the liquid. The compressed air mixes with the liquid c ...

'' to vacuum mud, sand and debris * Mist lifts use vaporized water to draw seawater in

ocean thermal energy conversion Ocean thermal energy conversion (OTEC) is a renewable energy technology that harnesses the thermocline, temperature difference between the photic zone, warm surface waters of the ocean and the deep sea, cold depths to run a heat engine to produce ...

systems

Petroleum industry uses

In the United States, gas lift is used in 10% of the oil wells that have insufficient reservoir pressure to produce the well. In the petroleum industry, the process involves injecting gas through the tubing-casing

annulus Annulus (or anulus) or annular indicates a ring- or donut-shaped area or structure. It may refer to: Human anatomy * ''Anulus fibrosus disci intervertebralis'', spinal structure * Annulus of Zinn, a.k.a. annular tendon or ''anulus tendineus comm ...

. Injected gas aerates the fluid to reduce its

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

; the formation pressure is then able to lift the oil column and forces the fluid out of the wellbore. Gas may be injected continuously or intermittently, depending on the producing characteristics of the well and the arrangement of the gas-lift equipment. The amount of gas to be injected to maximize oil production varies based on well conditions and geometries. Too much or too little injected gas will result in less than maximum production. Generally, the optimal amount of injected gas is determined by well tests, where the rate of injection is varied and liquid production (oil and perhaps water) is measured. Alternatively, mathematical models can be used to estimate the optimum gas injection rate. Such models offer significant economic benefit, since they allow one to simulate the performance of an actual or planned gas-lifted well using a digital replica of the well. Although the gas is recovered from the oil at a later separation stage, the process requires energy to drive a

compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps o ...

to raise the pressure of the gas to a level where it can be re-injected. The gas-lift

mandrel A mandrel, mandril, or arbor is a tapered tool against which material can be forged, pressed, stretched or shaped (e.g., a ring mandrel - also called a triblet - used by jewellers to increase the diameter of a wedding ring), or a flanged or t ...

is a device installed in the tubing string of a gas-lift well onto which or into which a gas-lift

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or Slurry, slurries) by opening, closing, or partially obstructing various passageways. Valves are technically Pip ...

is fitted. There are two common types of mandrels. In a conventional gas-lift mandrel, a gas-lift valve is installed as the tubing is placed in the well. Thus, to replace or repair the valve, the tubing string must be pulled. In the side-pocket

, however, the valve is installed and removed by wireline while the mandrel is still in the well, eliminating the need to pull the tubing to repair or replace the valve. A gas-lift valve is a device installed on (or in) a gas-lift mandrel, which in turn is put on the

production tubing Production tubing is a tube used in a wellbore through which production fluids are produced (travel). Background Production tubing is run into the drilled well after the casing is run and cemented in place. Production tubing protects wellbore ca ...

of a gas-lift well. Tubing and casing pressures cause the valve to open and close, thus allowing gas to be injected into the fluid in the tubing to cause the fluid to rise to the surface. In the lexicon of the industry, gas-lift mandrels are said to be "tubing retrievable" wherein they are deployed and retrieved attached to the production tubing. See gas-lift mandrel. Gas lift operation can be optimized in different ways. The newest way is using risk-optimization which considers all aspects for gas lift allocation.

History

Invented by Norman J. Rees and Albert W Zeuthen in 1956, Current Assignee ExxonMobil Oil Corp. Air lift uses compressed air to lift water in operations such as dredging and underwater archeology. It is also found in aquariums to keep water circulating. These forms of lift were used as far back as 1797 in mines to lift water from mine shafts. These systems used single point injection of air into the liquid stream, normally through a foot valve at the bottom of the string. Gas lift was used as early as 1864 in Pennsylvania to lift oil wells, also using compressed air, via an air pipe bringing the air to the bottom of the well. Air was used in Texas for large-scale artificial lift. In 1920 natural gas replaced air, lowering the risk of explosion. From 1929 until 1945 about 25000 patents were issued on different types of gas lift valves that could be used for unloading in stages. Some of these systems involved moving the tubing, or using wireline sinker bars to change the lift point. Others were spring operated valves. Ultimately, in 1944 W.R. King patented the pressurized bellows valve that is used today. In 1951 the sidepocket mandrel was developed for selectively positioning and retrieving gas lift valves with wireline.

References

External links

Kermit Brown. The Technology of Artificial Lift Methods, vol 2A. The Petroleum Publishing Company, 1980.“Subsurface Equipment/Artificial Lift: Maximizing Production from the Well”, May 1999 JPT

Video showing a bubble pump in action
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Petroleum industry uses

History

See also

References

External links