The selection of completion equipment and hardware is based on the reservoir,
field, wellbore and operational requirements that will achieve efficient, safe and
There are many types of components available, each of which may be specified
in a number of service or dimensional variations, (e.g. H2S or normal service).
Principal completion components are categorized as follows:
- Production packers
- Gas lift equipment
- Safety valves
- Tubing flow control equipment
- Completion accessories
production string. Completion packer types vary greatly and are typically
designed to meet specific wellbore or reservoir conditions, (e.g., single or
tandem packer configurations, with single, dual and triple completion strings).
Production packers can have several functions. However, the principal function
of a packer is to provide a means of sealing the tubing string from the casing or
liner. This seal must provide a long-term barrier compatible with reservoir
fluids or gasses and the wellbore annular fluid.
The production packer must also enable efficient flow from the producing (or
injection) formation to the tubing string or production conduit.
a downhole anchor for the tubing string. However, cup or isolation packers do
not anchor the tubing stringcontinued next However cup or isolation packers,
do not anchor the tubing string.
These hydraulically operated tubing flow control valves are used offshore, in
critical locations (next to a school or home) and areas of concern of the
environment, the reservoir, the facilities and the personel.
Sidepocket mandrels with dummy valves are run in new free flowing completions
where workover costs are high and the reservoir will require artificial lift to
This equipment expands the value of the completion by introducing flexibility.
Nipples, sleeves, plugs, chokes, test tools, standing valves, bomb hangers,
etc. could be utilized.
In most wellbores, the casing string or liner is a permanent component of the
completion system. Since casing replacement or repair procedures are
complicated and expensive, systems are designed (using packers) to protect
the casing from pressure differentials and corrosive conditions. The packer
and tubing string is typically easier to repair and/or replace than the casing
For Downhole Formation
High Pressure gas and fluids are generally encountered at some depth. In the
absence of heavy completion fluids, a packer provides an effective means of
isolation. The high pressure can then be controlled by subsurface safety
valves in the tubing string attached to the packer. This also enables some
control of pressure on the wellhead. By inserting a tubing plug in the packer,
creating a temporary bridge plug, workover work above the packer can be
carried out with a greater degree of safety.
For Zone Separation
In multiple zone completions, it is generally necessary to separate the producing
zones for the following reasons:
- Legality - Government regulations monitor produced flow-rates as
which is more easily accomplished through the use of a packer.
- Control of formation fluids - Frequently, high and low pressure
When using gas lift to enhance production, a packer is utilized to separate
the produced fluid pathway from the injected gas pathway down the
annulus. Packers are often used with ESP’s to facilitate control of well zones.
Tubing anchors are commonly used to increase the efficiency of rod pumps.
Anti-rotational anchors are commonly used with progressive cavity pumps.
Remedial / Repair Work
In situations where casing is damaged, two packers can be used to seal off and
bypass the damaged area. With the use of accessory completion equipment,
such as stingers and on-off attachments, tubing can be pulled for repair and/or
replacement without releasing the packer.