Flowhead (Surface Test Tree)
Flowhead consists of four gate valves: a master valve, two wing valves, and a swab valve. The outlet wing valve is act by hydraulic actuator. Above the swab valve is a lifting subassembly (sub) with a threaded connection. The threaded connection is often called a quick union which is used to connect auxiliary pressure equipment. Beneath the optional swivel are the master valve assembly and the bottom sub. In order to raise and lower a drill stem test (DST) string, elevators (clamps) are attached to the flowhead.
Flowhead is divided into two types: one is mater valve integralled in main block, the other is mater valve below main block.
Normally flowheads have a protection frame bolted to the main block to prevent damage caused by collision to the valves during transportation and operation.
Features
- Provides at least two surface pressure barriers
- Swivel allows rotation of the string without rotating the flowhead
- Kill line to be connected for pressure testing, injection, or killing the well
- Tools to be introduced and run into the well through the swab valve