To achieve critical flow, the upstream tubing head pressure must be larger than twice of the downstream flowline pressure
What are the functions of the casing head?
The casing head, which is also called the starting head or bradenhead, serves as an intermediate connection between the casing, well control equipment (e.g., blowout preventers) and subsequent casing and tubing spools.
In addition, the casing head provides a means of controlled access to the wellbore for pressure control and fluid returns during drilling.
What is a plastic energized-type seal and what is its purpose?
The plastic energized seal, often called a secondary seal, is activated by injecting plastic into ports located on the casing spool. This secondary seal, or packoff, seals against the casing OD and the ID of the wellhead and prevents both pressure communication between the casing strings and exposure of the flange seal to annular pressure.
Bowl Protector (sometimes called a wear sleeve or wear bushing)
Where is the backpressure valve located and what is its primary purpose?
Common types of BPVs either screw into the hanger or latch into a bushing in the hanger. The BPV is used for stopping flow up the tubing string, allowing removal of the BOPs, installation or repair of the Christmas tree, or the indefinite shut-in of a well. BPVs allow fluid to be pumped down the tubing. They are run and retrieved under pressure by use of a lubricator.
What conditions should a boll weevil tubing hanger be equipped with an extended neck with sealing element? Why?
A boll weevil tubing hanger is common in high-pressure wells, gas wells, and wells that produce corrosive or erosive materials
Tubing can be set in tension, compression, and neutral axial stress.
Tubing couplings are typically externally upsetCutaways of basic types of couplings) are of three basic types: external upset (EUE), nonupset (NU), and integral joint.
