Oil and gas production handbook - Process Control and ...
Oil and gas production handbook - Process Control and ...
Oil and gas production handbook - Process Control and ...
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components: the casing head, the tubing head, <strong>and</strong> the 'Christmas tree'Photo: Vetco<br />
international<br />
A typical Christmas tree<br />
composed of a master gate<br />
valve, a pressure gauge, a wing<br />
valve, a swab valve <strong>and</strong> a<br />
choke is shown here. The<br />
Christmas tree may also have a<br />
number of check valves. The<br />
functions of these devices are<br />
explained in the following<br />
paragraphs. Ill: Vetco international<br />
At the bottom we find the<br />
Casing Head <strong>and</strong> casing<br />
Hangers. The casing will be<br />
screwed, bolted or welded to<br />
the hanger. Several valves <strong>and</strong><br />
plugs will normally be fitted to<br />
give access to the casing. This<br />
will permit the casing to be<br />
opened, closed, bled down,<br />
<strong>and</strong>, in some cases, allow the<br />
flowing well to be produced<br />
through the casing as well as<br />
the tubing. The valve can be<br />
used to determine leaks in<br />
casing, tubing or the packer,<br />
<strong>and</strong> will also be used for lift<br />
<strong>gas</strong> injection into the casing.<br />
The tubing hanger (also called donut) is used to position the tubing correctly in the<br />
well. Sealing also allows Christmas tree removal with pressure in the casing.<br />
Master gate valve. The master gate valve is a high quality valve. It will provide full<br />
opening, which means that it opens to the same inside diameter as the tubing so that<br />
specialized tools may be run through it. It must be capable of holding the full<br />
pressure of the well safely for all anticipated purposes. This valve is usually left fully<br />
open <strong>and</strong> is not used to control flow.<br />
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