Gas well deliquification
Encyclopedia
Gas well deliqufication, also referred to as "gas well dewatering", is the general term for technologies used to remove water or condensates build-up from producing gas wells.
When natural gas
flows to the surface in a producing gas well, the gas carries liquid
s to the surface if the velocity
of the gas is high enough. A high gas velocity results in a mist
flow pattern in which liquids are finely dispersed
in the gas. Consequently, a low volume of liquids is present in the tubing or production conduit, resulting in a pressure drop caused by gravity acting on the flowing fluids. As the gas velocity in the production tubing drops with time, the velocity of the liquids carried by the gas declines even faster. Flow patterns of liquids on the walls of the conduit cause liquid to accumulate in the bottom of the well, which can either slow or stop gas production altogether.
Possible solutions to this problem include the installation of a velocity string, a capillary
string injecting foamers (often with corrosive
effects on surface wellhead seals), or a pump
to continuously or intermittently pump the water to the surface to remove the hydrostatic barrier that the water creates. A common practice is to use a device called a plunger
to lift the liquids. Improved electrical pumps coming onto the market may enhance the effectiveness of the technology.
The same concept is also applicable to oil
wells when they are at the end stage of production. In this case, the reservoir pressure drops to such a low level that it cannot lift the weight of the oil/water column to the surface. By injecting a gas (such as nitrogen) into the wellbore at a specific point, the density of the fluid column can be reduced to the point that the reservoir pressure is once again able to lift fluids to the surface.
When natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
flows to the surface in a producing gas well, the gas carries liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
s to the surface if the velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
of the gas is high enough. A high gas velocity results in a mist
Mist
Mist is a phenomenon of small droplets suspended in air. It can occur as part of natural weather or volcanic activity, and is common in cold air above warmer water, in exhaled air in the cold, and in a steam room of a sauna. It can also be created artificially with aerosol canisters if the...
flow pattern in which liquids are finely dispersed
Dispersive mass transfer
Dispersive mass transfer, in fluid dynamics, is the spreading of mass from highly concentrated areas to less concentrated areas. It is one form of mass transfer....
in the gas. Consequently, a low volume of liquids is present in the tubing or production conduit, resulting in a pressure drop caused by gravity acting on the flowing fluids. As the gas velocity in the production tubing drops with time, the velocity of the liquids carried by the gas declines even faster. Flow patterns of liquids on the walls of the conduit cause liquid to accumulate in the bottom of the well, which can either slow or stop gas production altogether.
Possible solutions to this problem include the installation of a velocity string, a capillary
Capillary action
Capillary action, or capilarity, is the ability of a liquid to flow against gravity where liquid spontanously rise in a narrow space such as between the hair of a paint-brush, in a thin tube, or in porous material such as paper or in some non-porous material such as liquified carbon fiber, or in a...
string injecting foamers (often with corrosive
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
effects on surface wellhead seals), or a pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
to continuously or intermittently pump the water to the surface to remove the hydrostatic barrier that the water creates. A common practice is to use a device called a plunger
Plunger lift
A plunger lift is an artificial lift method of deliquifying a natural gas well. A plunger is used to remove contaminants from productive natural gas wells, such as water , sand, oil and wax....
to lift the liquids. Improved electrical pumps coming onto the market may enhance the effectiveness of the technology.
The same concept is also applicable to oil
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
wells when they are at the end stage of production. In this case, the reservoir pressure drops to such a low level that it cannot lift the weight of the oil/water column to the surface. By injecting a gas (such as nitrogen) into the wellbore at a specific point, the density of the fluid column can be reduced to the point that the reservoir pressure is once again able to lift fluids to the surface.