Plug & Abandonment - Weatherford International

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World Trends and Technology for Offshore Oil and Gas Operations
February 2011
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P R O D U C T I O N O P E R A T I O N S
P&A innovations increase efficiency, safety
In the field, a combination of advanced technology and
aggressive engineering often provide the best solution
Plug and abandonment operations face
a long list of challenges, including
rising costs, safety concerns, environmental
issues, and rapidly growing
demand. Conventional methods
and tools are frequently unable to address
these concerns. Instead, the solutions are
being found in new technologies that are
yielding improved levels of efficiency and
performance.
These advances contrast with traditional
approaches, such as jackup rig installations,
that are typically slow-to-mobilize and expensive.
Traditional rigless P&A equipment
comes with cost and safety concerns, and
snubbing units generally expose personnel
to safety risks and can be difficult to move
from well to well.
Many of the recent advances center around
the development of versatile and compact
rigless intervention and well abandonment
systems. These systems are fit for purpose
and can include hydraulic pulling and jacking
units, cantilever systems with light duty
work decks, and casing jack configurations.
Lightweight and modular and with a minimal
footprint, these systems provide new levels of
Delaney Olstad
Philip O’Connor
Weatherford International Ltd.
mobilization and flexibility.
They are at the core of a suite of technologies
that provide a scalable P&A solution
ranging from casing jacks to light-duty work
deck and cantilever systems, to full-function
pulling and jacking units. Further integration
with a larger scope of service draws on
multiple resources including wellhead diagnostics,
running bridge plugs, tubing cutting
and removal, and remedial cementing
to improve safety and efficiency.
These technologies and capabilities combined
provide the tools for innovative, engineered
solutions that improve performance
on a range of P&A applications.
Growing demand
Complicating the P&A picture is the
greatly increased demand projected for services
due to 2010 changes in decommissioning
guidance for wells and platforms in the
Gulf of Mexico. The new guidelines from
the Bureau of Ocean Energy, Management,
Regulation, and Enforcement are expected
to add to activity by making P&A actions dependent
on well and structure status instead
of the lease status.
This anticipated increase comes on the
heels of record increases in temporary and
permanent abandonments in 2008 and 2009,
due in part to hurricane damage. According
to a recent webinar conducted by Offshore, 1
2009 capital expenditures were $650 million
to $1.4 billion, accounting for 835 permanent
abandonments, 744 temporary abandonments,
and 214 structure removals. The
activity is about 50% ahead of a busy 2008.
The new decommissioning guidance affects
an inventory of approximately 3,500 shallow
and deepwater wells that have been idle for five
or more years. Those wells must be plugged
and abandoned in the next three years. In addition,
there are approximately 2,000 wells idle
for less than five years and an additional 3,500
wells that have been temporarily abandoned.
All told, there is a very large waiting list of P&A
operations that must be addressed over a relatively
short time period.
New approach
Addressing this well inventory will require
a marked change in the efficiency and
innovation of P&A operations. A key part of
this change is the combination of advanced
technology and aggressive engineering that
is already providing solutions for many P&A
challenges.
The three following cases, one onshore and
two in the Gulf of Mexico (GoM), illustrate the
increasing importance of innovative thinking
and equipment to P&A performance. This enhanced
performance is central to improving
safety and reducing costs.
Each case depended on continuous communications
and extensive collaboration with
the clients. All three presented unique circumstances
that required innovation and the development
of fit-for-purpose components and
equipment.
The pulling and jacking unit is shown, deployed and positioned on the wedge deck.
Leaning six-pile platform
A 15° lean made P&A work on a hurricanedamaged,
six-pile platform particularly challenging.
The structure was loaded with pro-

P R O D U C T I O N O P E R A T I O N S
duction equipment and prior to the storm had
been operational with 10 producing wells and
one partially drilled conductor.
Underwater inspections showed one corner
leg of the platform had penetrated the
supporting shale on the seafloor and cause
the structure to lean. Nevertheless, the
structure was found to be relatively stable
and well conductor damage was limited to
bending at or below the mud line.
To conduct P&A operations on the live
wells, the platform was secured with a second,
four-pile platform positioned at the
leaning corner of the structure. Extensive
laser surveying established the exact relations
of the wellheads to the new structure.
Several P&A options were considered
and rejected for safety and cost reasons. A
snubbing unit would have required a major
engineering effort and would have put the
wellheads in harm’s way. A jackup rig of sufficient
size to cantilever over the well bay
area would have been cost prohibitive.
A new, lower load rating was established
for the compromised structure. These specifications
guided the development of a lightweight
pulling and jacking unit. A modular
design for the unit was used to provide high
mobility and a small footprint. An integrated
self-clamp skidding system allowed the unit
to be easily skidded from well to well.
Design of the unit depended on close
teamwork with customer personnel and
strict attention to platform constraints. Limited
deck space required measurement of
each equipment component. Exact equipment
weights were determined to ensure
that the total equipment load on the structure
fell within the weight parameters after
allowing for an over-pull of approximately
100,000 lb.
Special wedge deck
To accommodate the intervention and
well abandonment system, which includes
the pulling and jacking unit, a specially-designed
wedge deck was built and attached
to the original drill beams on the damaged
structure. Placed over the wells, it provided
a level work area for the unit to perform pulling
and jacking operations.
Plugging and abandoning operations involved
an experienced crew working around
the clock. Extensive training was conducted
to familiarize the crew with the specialized
equipment and the risks associated with
working on a structure that was leaning at
a 15° angle.
In phase one of operations, a daylight crew
was deployed to the platform to begin the wellhead
diagnostics. Phase two involved wireline
work and plugging of all open perforations.
During this time, the new hydraulic pulling
and jacking unit was being manufactured
Jacking units provided the lift to return the wellhead and snubbing unit to vertical.
and set up per the operational requirements
and client requests. Tests were performed
to simulate bends in the production tubing
and casing while running bottomhole assemblies.
The intervention and well abandonment
system was then deployed to the platform
and the pulling and jacking unit was assembled
on the new wedge deck.
Once the pulling and jacking unit was
in place, phase three began. Wireline inspection
indicated that several wells would
require coiled-tubing work to plug open
perforations and meet regulatory requirements.
Crane support was limited by winds
in excess of 35 mph, so the rigless pulling
and jacking unit, which can operate at nearly
twice those wind speeds, was used. Significant
savings were realized by having the
unit support the coiled-tubing operations.
The change also freed the crane for other
work.
Custom hydraulic clamps
Moving the unit from well to well on
the structure was efficient with moving
times that average an hour on most wells.
The skidding process benefited from custom-manufactured,
hydraulically actuated
clamps that fit on virtually any combination
of beam width and flange thickness.
On completion of the coiled tubing work,
phase four began by perforating, cutting
and pulling the production tubing and casing.
Safe and efficient retrieval and laying
down of tubulars was enhanced by the load
capabilities and compact design of the pulling
and jacking unit.
An integrated jacking floor was used
to remove stuck casing hangers. When a
hanger became stuck in the wellhead, it was
a simple operation to spear into the tubular
to be pulled, and then use the built-in jacking
system to remove the stuck hangers.
Phase five involved cutting the remaining
well casings approximately 15 ft below
the mud line. The pipe pulling and jacking
features were used to trip 3 1/2-in. OD drill
pipe with cutting assemblies into the wells.
The cuttings for all of the well conductors
were completed without incident. Boring
and sawing equipment were used to lay
down the cemented well conductors in 40-ft
lengths.
The pulling and jacking unit was a costeffective,
safe, and efficient means to complete
the job. It eliminated drilling-rig costs
and the development of an alternative
method. The unit was manufactured quickly
and all necessary work was completed two
months ahead of schedule, which resulted
in significant cost savings. During the 299
days/49,476 man-hours spent on location,
there were 2,276 Job Safety and Environmental
Impact Analyses conducted with no
recordable injuries or operational and environmental
incidents.
Frac damage
Failure of a wing valve during fracturing
operations on a newly completed 16,000-ft
well released pressure that bent the 10 3/4-

P R O D U C T I O N O P E R A T I O N S
A unique adjustable cantilever system on
the lift boat allowed the angle of the wells
to be matched.
in. casing at approximately 12° just below
the wellhead. After removing the
drive pipe and cement to expose the
bent casing, it was decided to rig-down
the wellheads and remove the damaged
pipe.
Mobilizing a rig and crew presented
significant time and cost constraints.
To expedite work and safely cut expenses,
the alternative solution specified
a 385-ton casing jack, heavy-duty
work beams and other specialized P&A
equipment. Operations began with removing
5 1/2-in. and 7 5/8-in. casing
hangers. Free travel of the hangers
required jacking them out at the same
angle as the bent casing. The task was
complicated by jacking loads of 250,000 lb
on the 5 1/2-in. casing and 450,000 lb on the
7 5/8-in. casing. To address the lean, angled
beams were set under the jacks to match the
bend in the casing.
Once the casing-hanger slips were removed,
both sets of casing were lowered
into the wellbore below the 10 3/4-in. hanger.
The damaged 10 3/4-in. casing was then
cut off and a new wellhead was installed.
The angled beams were replaced with level
beams and the original wellhead configuration
was restored. The entire operation,
including setup and rig-down, was accomplished
in two 12-hour days.
Fishing operations on the same well resulted
in another problem remedied with
the P&A equipment. When jarring efforts
exceeded compressive limits on the 10 3/4-
in. casing, the casing collapsed on itself and
threatened the stability of a snubbing unit
rigged up 97 ft above the surface with 15,000
lb of 2 7/8-in. tubing. To deal with the situation,
two 285-ton jacks were mobilized along
with two 20-ft high-strength, 12-in. beams.
It was determined that a 7 1/6-in., 15,000
psi frac valve on the wellhead was a safe and
satisfactory lifting point. The jacks were
placed on each side of the wellhead and the
beams were placed under the valve. The
jacks were simultaneously activated to support
the snubbing unit while bringing the
system back to a true vertical position.
Once the snubbing unit was corrected
back to vertical, the tubing was removed
and the unit was rigged down. The angled
beams were positioned to allow free travel
of the casing hanger slips and repositioning
of the casing. After the damaged casing was
cut off, the level beams were rigged up and
a new wellhead was installed.
A hurricane-damaged satellite platform
had two wells leaning at approximately 20°.
The precarious situation required an innovative
P&A solution. Operations had to be
conducted at the same angle as the wells
because of the concern that an attempt to
straighten the wells could result in failure of
the casing below the mud line at the bend
point.
The solution began with the use of a lift
boat to support the P&A operations rather
than a jackup rig, due to debris on the ocean
floor. To address the angled work deck, the
lift boat was outfitted with a unique cantilever
system and light duty work deck that
extended off the side of the boat.
Instead of conventionally welding the
beams and work deck in place, the cantilever
system was built so it could be adjusted
to match the angle of the wells. In just two
weeks, a clamping system was designed
to fasten the cantilever beams to the lift
boat and the system was outfitted with two
50,000-lb, single-line winches. The design
provided the flexibility needed to position
the lift boat and complete the work.
On the first well, the P&A procedures involved
mechanically cutting and pulling 10
3/4-in. casing and 16-in. casing, which was
cemented into 30-in. conductor pipe. The
10 3/4-in. casing was cut using newly-developed
guillotine saws. The remotely-operated,
multi-string saws are self-aligning and
self-clamping to minimize risk to personnel,
and feature a hydraulic stabilizer to improve
cutting efficiency.
When attempting to cut the 16-in. casing,
it was discovered and verified by camera
that the casing had parted approximately
12 ft above the mud line. The remotely-operated
guillotine saw was deployed to a point
approximately 20 ft above the water
line to cut off the casings and facilitate
entry into the wellbore.
Deployed underwater, the saw first
cut the 30-in. and 16-in. casing 5 ft
above the mud line. Once the sections
of casing were retrieved, the loose
piece of 16-in. casing was retrieved
with a spear run on 3 1/2-in. drill pipe.
A hydraulically-actuated mechanical
cutter was then deployed on 3 1/2-in.
drill pipe, the 30-in. casing was cut 15 ft
below the mud line, and the remaining
casing and conductor were retrieved
without incident.
For the second well, the objective
was to remove the crow’s nest and
cut and pull 9 5/8-in. casing cemented
inside 30-in. conductors. To begin the
P&A operations, two abandoned pipelines
were removed by divers, per (at
that time) MMS rules and regulations.
Once again, the guillotine saw was deployed
to a point below the crow’s nest to
cut off the casings and facilitate entry into
the wellbore.
A hydraulically actuated mechanical cutter
was then deployed on 3 1/2-in. drill pipe
and the 30 x 9 5/8-in. casing was cut at 15
ft below the mud line. This section of casing
and conductor was retrieved without
incident.
The successful completion of the project
was attributed to the timely design and
mobilization of the adjustable cantilever
system, the ability to work efficiently on the
angled work deck, and the efficiency of the
remotely operated, self-aligning, self-clamping
guillotine saw.
Enhancing P&A performance
In each of these cases, a combination
of advanced technology and aggressive
engineering was key to providing the best
solution. The development of the versatile
intervention and well abandonment system,
including the compact rig-less hydraulic
pulling and jacking units are the basis
for this capability. Integrated with a broad
service resource that draws on P&A and
other related capabilities, the technology
has proven itself to be an enabler for the
innovative, engineered solutions that are increasingly
required to improve P&A performance.
These enhancements are reducing
costs, improving operational efficiency and
strengthening safety across a full spectrum
of P&A applications from the most basic to
the most challenging. •
Reference
1. Gulf of Mexico Decommissioning Outlook, Mark
Kaiser, Louisiana State University Center for Energy
Studies, Offshore, September 2010.