Page 33 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

At the bottom we find the casing head and casing hangers.
The casing will be screwed,
bolted or welded to the
hanger. Several valves and
plugs will normally be fitted to
give access to the casing.
This will permit the casing to
be opened, closed, bled
down, and in some cases,
allow the flowing well to be
produced through the casing
as well as the tubing. The
valve can be used to
determine leaks in casing,
tubing or the packer, and will
also be used for lift gas
injection into the casing.

The tubing hanger (also
called a donut) is used to
position the tubing correctly in
the well. Sealing also allows
Christmas tree removal with
pressure in the casing.

Master gate valve. The
master gate valve is a high
quality valve. It provides full
opening, which means that it
opens to the same inside diameter as the tubing so that specialized tools
may be run through it. It must be capable of holding the full pressure of the
well safely for all anticipated purposes. This valve is usually left fully open
and is not used to control flow.

The pressure gauge. The minimum instrumentation is a pressure gauge
placed above the master gate valve before the wing valve. In addition other
instruments such as a temperature gauge will normally be fitted.

The wing valve. The wing valve can be a gate or ball valve. When shutting
in the well, the wing gate or valve is normally used so that the tubing
pressure can be easily read.

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