Page 31 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

3.4.2 Completion

Well completion commonly refers to the process of finishing a well so that it
is ready to produce oil or natural gas. In essence, completion consists of
deciding on the characteristics of the intake portion of the well in the targeted
hydrocarbon formation. There are a number of types of completions,
including:

• Open hole completions are the most basic type and are only used in
very competent formations, which are unlikely to cave in. An open
hole completion consists of simply running the casing directly down
into the formation, leaving the end of the piping open without any
other protective filter.

• Conventional perforated completions consist of production casing
run through the formation. The sides of this casing are perforated,
with tiny holes along the sides facing the formation, which allows
hydrocarbons to flow into the well hole but still provides a suitable
amount of support and protection for the well hole. In the past, 'bullet
perforators' were used. These were essentially small guns lowered
into the well that sent off small bullets to penetrate the casing and
cement. Today, 'jet perforating' is preferred. This consists of small,
electrically-fired charges that are lowered into the well. When ignited,
these charges poke tiny holes through to the formation, in the same
manner as bullet perforating.
• Sand exclusion completions are designed for production in an area
that contains a large amount of loose sand. These completions are
designed to allow for the flow of natural gas and oil into the well, but
at the same time prevent sand from entering. The most common
methods of keeping sand out of the well hole are screening, or
filtering systems. Both of these types of sand barriers can be used in
open hole and perforated completions.
• Permanent completions are those in which the completion and
wellhead are assembled and installed only once. Installing the
casing, cementing, perforating, and other completion work is done
with small diameter tools to ensure the permanent nature of the
completion. Completing a well in this manner can lead to significant
cost savings compared to other types

• Multiple zone completion is the practice of completing a well such
that hydrocarbons from two or more formations may be produced
simultaneously, without mixing with each other. For example, a well
may be drilled that passes through a number of formations on its

29