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Well integrity
Application of technical, operational and
organizational solutions to reduce risk of
uncontrolled release of formation fluids
throughout the life cycle of a well.
There are various facets to well integrity,
including accountability/responsibility, well
operating processes, well serviceprocesses, tubing/annulus integrity,
tree/wellhead integrity and testing of
safety systems.
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Accountability/responsibility
Accountabilityis the position that
ensures a particular task is being done.
They typically control the budget and
organizational chartstructure.
Responsibilityis the position that actually
does the task. There are a variety of tasks
associated with well integrity andresponsibility can reside with a fields
well operations engineer, operators, well
service technicians, etc.
http://en.wikipedia.org/wiki/Organizational_charthttp://en.wikipedia.org/wiki/Well_serviceshttp://en.wikipedia.org/wiki/Well_serviceshttp://en.wikipedia.org/wiki/Organizational_chart8/13/2019 34-Well Integrity and Intervention
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Well operating processes
This includes processes such as personnel
competency, well startup!operating!
shutdown procedures, process to report
anomalies, corrosion/erosion control, etc.
Well service processes
This includes processes such as personnel
competency, intervention procedures, etc.
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Tubing/annulus integrity
This refers to the integrity of the
production tubing. "ommon threats to
tubing integrity are erosion and corrosion
by production fluids, which remove the
steel. The other threat is pressure
differential between the tubing and the A
annulus. #f it e$ceeds the rated pressureof the tubing, there is a risk of tubing burst
or tubing collapse
http://en.wikipedia.org/wiki/Production_tubinghttp://en.wikipedia.org/wiki/Production_tubing8/13/2019 34-Well Integrity and Intervention
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This refers to the integrity of the
casing strings, which bound the annuli. Allannuli will naturally be filled to some level
with brine or other fluids from the
completion, though the A annulus mayhave gas down to the lowest gas lift valve
if the well is gas lifted.
The ma%or integrity issues comes from thedifferential pressure across the casings
due to the weight of brine on either side.
To protect well integrity, each annulus will
have a
http://en.wikipedia.org/wiki/Casing_(oil_well)http://en.wikipedia.org/wiki/Annulus_(oil_well)http://en.wikipedia.org/wiki/Gas_lifthttp://en.wikipedia.org/wiki/Gas_lifthttp://en.wikipedia.org/wiki/Annulus_(oil_well)http://en.wikipedia.org/wiki/Casing_(oil_well)8/13/2019 34-Well Integrity and Intervention
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Tree and wellhead integrity
This refers to the integrity of the surface
)or subsea* e+uipment. Thewellheadand
the treeare typically suitably engineered
to be able to withstand the normal
operating pressures. The ma%or integrity
issues for these components surround the
operation of the valves, which are prone toleaking. or this reason, valves must be
routinely maintained.
http://en.wikipedia.org/wiki/Subseahttp://en.wikipedia.org/wiki/Wellheadhttp://en.wikipedia.org/wiki/Christmas_tree_(oil_well)http://en.wikipedia.org/wiki/Christmas_tree_(oil_well)http://en.wikipedia.org/wiki/Wellheadhttp://en.wikipedia.org/wiki/Subsea8/13/2019 34-Well Integrity and Intervention
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Testing of safety systems
This refers to testing of surface and
subsurface safety systems.
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Tubing hanger modified to prevent direct
impingement
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Well intervention
-uring, or at the end of its productive life,that alters the state of the well and or well
geometry, provides well diagnostics or
manages the production of the well. Pumping
This is the simplest form of intervention as
it does not involve putting hardware intothe well itself. re+uently it simply involves
rigging up to the kill wing valve on the
"hristmas treeand pumping the
chemicals into the well.
http://en.wikipedia.org/wiki/Christmas_tree_(oil_well)http://en.wikipedia.org/wiki/Christmas_tree_(oil_well)8/13/2019 34-Well Integrity and Intervention
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Wellhead and Christmas tree
maintenance
The comple$ity of this operation can vary
depending on the condition of the
wellheads. 'cheduled annual
maintenance may simply involve greasing
and pressure testing the valve on the
hardware. 'ometimes the downhole safety
valve is pressure tested as well.
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Slickline
'lickline operations may be used for
fishing, gauge cutting, setting or removing
plugs, deploying or removing wireline
retrievable valves and memory logging.
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Coiled tubing
"oiled tubing is used when it is desired to
pump chemicals directly to the bottom of
the well, such as in a circulating operation
or a chemical wash. #t can also be used
for tasks normally done by wireline if the
deviation in the well is too severe for
gravity to lower the tool string andcircumstances prevent the use of a
wireline tractor.
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Snubbing
Also known as hydraulic workover, this
involves forcing a string of pipe into the
well against wellbore pressure to perform
the re+uired tasks. The rig up is largerthan for coiled tubing and the pipe more
rigid.
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Subsea well ntervention
'ubsea well interventions offer up many
challenges and re+uires much advanced
planning. The cost of subsea intervention
has in the past inhibited the interventionbut in the current climate is much more
viable. These interventions are commonly
e$ecuted from ight/medium interventionvessels or &obile ffshore -rilling 0nits
)&-0* for the heavier interventions such
as 'nubbing and 1orkover drilling rigs.
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