Slug catcher is a static equipment used in the upstream oil production facilities to minimize the slug from oil and gas pipeline.
Fluids extracted from oil and gas reservoirs contain crude oil, natural gas, water, salts etc.
A slug is a large quantity of gas or liquid that exits in the pipeline.
The multiphase flow in a pipeline often leads to formation of slug flow.
Slug catcher, hence, is the name of a unit in which slugs at the outlet of pipelines are collected or caught and it is a vessel with sufficient buffer volume to store the largest slugs expected from the upstream system.
It is located between the outlet of the pipeline and the processing equipment, buffered liquids can be drained to the processing equipment at a much slower rate to prevent overloading the system.
As slugs are a periodical phenomenon, the slug catcher should be emptied before the next slug arrives.
A slug catcher permanently connected to the pipeline will buffer all production, including the slugs, before it is sent to the gas and liquid handling facilities.
Alternatively, the slug catcher can be by-passed in normal operation and be brought online when a slug is expected, usually during pigging operations.
An advantage of this set-up is that inspection and maintenance on the slug catcher can be done without interrupting the normal operation.
Slug catchers are designed in different forms:
- A vessel type slug catcher is essentially a conventional vessel. This type is simple in design and maintenance.
- A finger type slug catcher consists of several long pieces of pipe (‘fingers’), which together form the buffer volume. The advantage of this type of slug catcher is that pipe segments are simpler to design for high pressures, which are often encountered in pipeline systems, than a large vessel. A disadvantage is that its footprint can become excessively large.
- Protects downstream equipment & pipelines from damaging liquids
- Efficiently manages high liquid volumes generated from pigging
- Optional crash level controller & secondary outlet to handle slug overload
- Ensures a first separation of the liquid contained in the gaseous part that is separated
- Reduce downtime & maintain production with proven pre-engineered design