Flowhead (Surface Test Tree)

General:

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Flowhead - surface test tree consists of four gate valves: a master valve, two wing valves, and a swab valve. The outlet wing valve is opened and closed using an hydraulic actuator. Above the swab valve is a lifting subassembly (sub) with a threaded connection. The threaded connection is often called a quick union. The quick union is used to connect auxiliary pressure equipment which is needed if tools are to be run downhole. Some flowheads have a protection frame bolted to the main block to prevent damage to the valves during handling. 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.

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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.

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The Flowhead is the primary device for controlling the well and allowing the introduction of wireline, mainly used for controlling the surface pressure and fluid and gas movement during drill stem testing, and more easy to release the formation over pressure in short time at the beginning of well open. Can show the actual fluid movement in high pressure well testing as small resistance of fluid, not easy to block. And the flowhead is full bore equipment to meet the tools through smoothly. When during the drill stem testing, Acid job, fracture Job, Stage cementing job, Reformatting job can also be processed without lifting out the string, can make the job more coefficient, reduce working time.

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