Definition - What does Slug Area mean?
Slug area can be defined as that area in the tubing where slug accumulates. During intermittent gas injection, gas is delivered to the well for a short period of time known an 'on-time' followed by an 'off-time' during which no gas is delivered. It helps in the gas production process and is installed in wells with low bottom hole pressure.
Gas is injected through a choke on the surface and then into the tubing. In the tubing, the gas forms three areas namely: gas column area, film area and slug area.
Trenchlesspedia explains Slug Area
Slug is a small volume of fluid produced in a gas well that is higher in density than the main fluid in the production system. They are separated by large pockets of gas in the tubing. Some pipelines transport gas and liquid and operate in the slug flow regime.
The liquid tends to settle to the pipeline bottom under the influence of gravity while the gasses rise up. In some operating conditions, the liquid and gas are not evenly distributed but travel in pockets of liquid and gas.
Intermittent gas injection can be used to propel the slug to the surface. The equipment consists of a compressor, choke, and valve in the mandrel. The compressor imparts high pressure to the gas which is injected in the choke by which the casing pressure increases and opens the gas lift valve.
The gas enters the tubing through the valve propelling the liquid slug to the surface. Intermittent gas lift increases bottom hole pressure and propels liquid to the surface.