Decommissioning of Offshore Platforms - PCE-UAE

Decommissioning of Offshore
Platforms
Speaker: Haitham K. M. Mokhtar
(MIMarEST)
B.Sc., P.G. Dip., PMP-Prep, CIPM, Prince-2.
Sr. Project Engineer- Brownfield Projects
ADMA-OPCO
10 June 2014.
History of Offshore Decommissioning
There are around 45,000 O&G offshore platforms around the globe.
These platforms vary from simple vertical caissons supporting one well in 10 feet
of water to a huge structure in 1700 feet of water supporting some 50 wells and a
TLP’s (Tension Leg Platforms) in 3500 feet of water depth.
Approximately one-fourth of these platforms are more than 35-40 years old, some
dated as far back as the 1950s), As these structures come to the end of their
economic lives, they must be decommissioned.
Platform abandonment has five steps:
• Obtaining necessary permits and approvals
• Plugging the well
• Decommissioning (removing hydrocarbons from equipment)
• Removing the platform.
• Clearing the site.
Since 1987, annual decommissioning have involved about 250 to 350 globally.
Some of the difficulties with decommissioning is finding the right balance between :
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Technical Feasibility
Environmental Protection
Health and Safety
Cost
Public Opinion
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Life Cycle of an Offshore production platform
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Factors in Selecting Removal Methods
Factors to consider in selecting a method for each platform removal include
1.
2.
3.
4.
5.
6.
The age of the platform
The location and water depth
The configuration and type of platform
The weight of the lifts and Soil strength
Weather conditions, and scour.
International and National Laws and Regulations
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What can be decommissioned in an offshore old-field:
1. Top side facilities (completely or partially)
2. Abandoned (non productive) wells
3. Decks
4. Jackets
5. Sub sea pipelines
6. Sub sea wells.
7. Sank Rigs (salvage)
8. Damaged offshore platforms
(post hurricanes, earthquakes or blasts)
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Decommissioned platforms can go for
1.
2.
3.
4.
5.
6.
Scrap
Re-use for functions besides oil and gas production
Using the structures in part or whole as artificial reefs
Conversion of offshore structures into fish farms
Prisons or military outposts.
Touristic offshore escapes (new approach) (Fishing/Diving/Seawater sports)
The costs for decommissioning services and equipment are currently challenging
and competitive.
In addition, the cost for fabricating new structures is increasing… one current trend
for offsetting costs is to reuse a portion or all of the offshore facility.
Although reuse has primarily been used in the (GoM) Gulf of Mexico, many
operators are considering this option in other locations, such as West Africa and
Southeast Asia.
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Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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Diagram of dismantling and abandonment options for offshore
installations and component parts.
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The complete abandonment of a platform well involves five steps
(Permits/Plugging Abandon/Purging Hydrocarbon/Removal/ Site cleaning)
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CUTTING TECHNIQUES
Explosive cutting techniques
Bulk Explosive Charges
The most commonly used technique for cutting piles and conductors is with bulk explosives.
Castable and moldable explosives, have high velocity on detonation, and shattering power
that is 15 to 30 percent higher than TNT, and are not as dangerous to handle as other high
explosives and can be molded in the field to the required size and shape.
Bulk charges can be shaped to fit pile or well dimensions that differ from the construction
drawings. For example, if the smallest casing string in a well is 7” Dia. instead of 9.5 “ Dia,
as anticipated, bulk explosives can be reformed into a smaller container with little or no
delay. Bulk explosives can also be deployed in conventional piles and wells without the use
of divers.
Bulk charges are lowered into the prepared piles and wells and detonated nearly
simultaneously (with a 0.9-second delay) in groups of eight or less. All of the piles and wells
can be severed within an hour or two.
The cost of bulk explosive cutting services is the lowest of all available alternatives
In addition to the environmental impact, the explosive force sometimes “bells” out piles and
wells so piles cannot be pulled out through jacket legs. In these cases, the jacket must be
lifted with the piles and the “belled” portion cut off.
Explosives, you tube link
Detonation, you tube link
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Non-explosive Cutting Techniques
Mechanical Cutters
Cutting mechanisms that use
hydraulically actuated,
carbide-tipped tungsten
blades to mill through tubular
structures .
The power swivel turns the
drill string so that the milling
blades are forced outward
hydraulically to cut the pile or
well
Non cemented Legs or
Stings
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Abrasive Cutters
Mechanisms that inject cutting materials
into a water jet and abrasively wear away
steel.
(also called sand cutters, abrasive jet
cutters, or abrasive slurry cutters).
There are two types presently in use:
(1) cutters that use sand or slag mixed
with water at relatively low pressure (4,000
to 10,000 psi) and high volume (80 to 100
gallons/minute).
(2) Cutters that use garnet or other
abrasive materials injected at the nozzle at
relatively high water pressure (50,000 to
70,000 psi) with lower water volume.
cutting shallow-water, open-pile, wellprotector jackets; single-thickness, small
vertical caissons; and wells with uncemented casing strings
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Subsea water jet cutting goes ultra-deep and ultra-high pressure
Cutting of 50m of
12mm thick steel,
independent of depth,
in a single deployment
It typically involves a
UHP (3900 bar) stream
of water with an
abrasive, such as
garnet, added.
Using an ROV
Using a Diamond Wire Saw
Movie 1, you tube link
Movie 2, you tube link
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Diver Cuts
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Hydraulic Shears
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Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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Leave-in-Place Option
Advantages
Disadvantages
No harm to marine life
Maintains unnatural habitat
Immediate cost savings
Maintenance costs escalate with age
 requires protective coating above water
 requires cathodic protection under water
 requires navigation-aid lights and horns
 remains susceptible to storm damage
Provides recreational fishing, diving habitat
Continues conflicts with other users
Provides emergency safe havens
Potential liabilities
 unauthorized boarding
 collisions
 surface and subsurface navigation hazards
Maintains status
 structure remains visible
 requires no research and development
 requires no site clearance
 provides migratory animal habitat (surface)
 provides reef habitat (subsurface)
May require eventual removal with
 reduced structural integrity
 increased safety risk
 increased cost
Negatively affects construction/removal industry
No recycling of steel
Requires changes in regulations and laws
Suitable for structures at water depth more
than 400 feet
Not Suitable for structures at water depth
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less than 400 feet
Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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Partial Removal Option
Advantages
Disadvantages
Potentially reduces harm to marine life
during removal and maintains some reef
habitat
Does not return habitat to natural state
Eliminates habitat structure in upper range of
water column
Potentially cost effective
 requires no maintenance
 requires no site clearance
Must maintain buoys
Useful only in water depths allowing sufficient
clearance
Potentially increases diver risk during removal
May provide recreational fishing and diving
habitat
Decreases shrimping access
Operators released from liability
Liability attaches to regulatory agency
 court test inevitable
 creates navigational hazards (surface and
subsurface)
Encourages innovative removal methods
Loss of resources
 eliminates surface habitat
 no recycling of steel
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Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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Topple-in-Place Option
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This option would be less expensive for owners than total removal (no
transportation charges) and would be of some benefit to the marine
environment.
But it would be of no benefit to shrimpers.
It would benefit commercial and, particularly, sport fishermen if the structure is
relatively close to shore
The use of explosives could be minimized
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Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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Complete Removal Option
AT 15 FEET BELOW MUDLINE
Advantages
Disadvantages
Meets shrimper requirements
maintains clearance for trawlers
Environmental impacts
 relocates or eliminates reef habitat
 fish kill from explosives
Requires no changes in regulations or
laws
Expensive to operators
 explosives require an observer program
 restricts use of explosives
 discourages development of nonexplosive
techniques
 requires transportation to shore or reef
site
Poses no navigational hazards
Requires site clearance
May require backfill
Eliminates liability and site maintenance
Hazardous to divers
Allows reuse and recycling
Potential removal problems from soil skin
friction at 15 feet below mudline
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Complete Removal Option
AT SHALLOWER 5 FEET BELOW MUDLINE OR LESS
Advantages
Disadvantages
Immediate cost savings
requires less jetting
minimizes problems from soil skin
friction
Requires changes in regulations and laws
Encourages use of non-explosive
methods
less hazardous to divers
easier to clean for access by mechanical
or abrasive tools
Explosives may still be necessary in some
cases although advanced techniques using
smaller charges could be used
Meets shrimpers requirements
nothing remains above mud line
Site clearance required
Reuse or recycling possible
Environmental impact
relocates or eliminates reef habitat
requires disposal
Poses no navigational hazards
Requires no backfill
Eliminates liability and site maintenance
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Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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In-Situ Complete Removal
In-situ removal is carried out at
the platforms original locationAfter the deck is removed and the
piles severed, the jacket is cut
and removed in sections that the
HLV can handle.
All cuts are made below water by
divers or ROV and are assisted
with external abrasive, diamond
wire or conventional torch cutting
tools.
The HLV is rigged to each section
that is being cut Upon completing
each section cut, the HLV
removes the jacket piece and
secures it to the cargo barge .
The process is repeated until the
jacket is completely removed
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Removal Options
1. Leave-in-Place Option
2. Partial Removal Option
3. Topple-in-Place Option (Jackets)
4. Complete Removal Option
5. In-Situ Complete Removal
6. Complete Removal — Jacket Hopping
Perenco UK executes the heavy lift removal of the Welland gas production platform in the southern North Sea.
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Complete Removal — Jacket Hopping
It handles a jacket that is too large and
heavy for a conventional HLV.
After the deck is removed and the piles
severed, the jacket is then made buoyant
to reduce the bottom weight. To maximize
buoyancy, closure plates are welded to the
piles and the water inside each pile is
evacuated. Having de-ballasted the jacket.
It is then lifted off the sea floor by the HLV.
The jacket is supported by the HLV’s crane
off to the stern of the HLV. Rope hawsers
are passed around two of the jacket legs
and secured to the stern of the HLV.
The jacket is then boomed away from the
stern of the HLV until the hawsers are tight
The rope hawsers keep the jacket from
swinging and being pulled out of the boom
radius by its movement through the water.
The HLV’s anchors are shifted or completely
picked up and the jacket is towed to
shallower water .
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Above figure shows the same sample jacket in 427-ft water depth
configured to be cut by the jacket hopping method. The number of jacket
sections are reduced from 6 (in-situ) to 5 by hopping the jacket in.
A route survey should be conducted to determine the tow route and
locations to set and cut the jacket. Also. the survey should identify anything
on the bottom that is not charted. Le. ship wreck, oyster beds. etc
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Example of Decommissioning works in the UAE
Company
Platform/ Piplines
Year
Decomm. Type
Utilization of Decommissioned Parts
ADMA-PCO
Umm Shaif 1 (US1),
US2, US3
1998
Complete Removal
Scrapped, install new monopods in the same
place
ZADCO
Arzana complex
1994
Leave in place
Mothballed
ADMA-PCO
ZAP (Zakum
Accommodation
Platform)
1990
Complete Removal
Accommodation module integrated decks
were cut from ZCSW and installed in ZWSC
ADMA-OPCO
ZCSC (Zakum Central
Super Complex)
1986
Leave in place
Mothballed
In 1991 it was de-mothballed partially, then
completely de-mothballed in 2011
ADMA-OPCO
Gas Gathering2
@ ZWSC
1986
Leave in place
Mothballed
ADMA-OPCO
Umm Shaif Super
Compex (USSC)
1993
Complete Removal
of old Inclinator unit
Scrapped
(Post a fire)
ADMA-OPCO
35 subsea pipelines
from Zakum Filed
2014
Removal
Scrap
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Structural Integrity Management (SIM)
SIM systems can ensure longer term asset integrity, taking into account
the operations, life extension, and decommissioning phases of the
asset life cycle.
It should be in place from the cradle-to-grave of an asset.
A robust SIM system is designed to ensure:
1.Safety of those working offshore
2.Continued production
3.Protection of the environment
4.Legislative compliance
5.Industry best practice.
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The requirement for SIM does not stop when O&G production is over.
SIM plays a vital role in the safe and successful decommissioning of
offshore infrastructure.
The SIM system provides a central location for platform knowledge,
containing information about the structure, its weight, configuration, changes
and modifications, and current condition. The retention and availability of
this information forms a critical part of decommissioning planning.
When considering removal options as part of the decommissioning process,
SIM is used to take into account the integrity of the topside and the jacket,
so options can be assessed according to the robustness of the structure for
safe removal, transportation, and load-in.
If effectively implemented and maintained, the SIM system is there to
provide the required structural integrity assurance from design to complete
decommissioning
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Future of Decommissioning:
Offshore decommissioning is growing more complex and challenging.
At the same time as work depths increase, the recovery targets get heavier,
and the configurations of the targets on the seabed become more difficult to
manage.
North sea:
470 installations and around 10,000 km of pipelines.
Estimate to decommission these facilities between 2010 and 2040
Estimated US$88.4 billion (£57.6 billion) business opportunity is there!
GOM:
2016 total idle wells
400 total idle platforms
12,628 Miles of abandoned Pipelines
2425 Miles of pipelines out of service
Estimated US$100 billion business opportunity is there!
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Examples of Recent Decommissioning works worldwide
October 2010,
VB 10,000 is the
largest lift vessel
ever built in the
United States
Removes a jacket
from its location as
part of a
decommissioning
project in the GOM
Movie, you tube link
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2008, GoM :Proserv has been awarded a $7 million contract for the
abandonment of two platforms (at 11 m and 59 m ), along with associated wells,
plus the removal of pipelines and subsea tie-ins for a major independent oil and
gas company. They used a 1,300-ton (1,179-metric ton) derrick barge, diving
crew, and dive support vessel for the removal of the platforms and for the
abandonment of the pipeline and associated subsea tie-in.
2009, UK: Shell awarded AF Group (AFG) a $30 million contract for the
decommissioning of six platforms from the Indefatigable gas field in the British
sector of the North Sea. Work was set to recycle around 13,000 tons of steel and
equipment from the structures.
2013, North Sea: ExxonMobil awarded the Decom. Of Brent field to Able UK.
The Brent field comprises four platforms (Alpha, Bravo, Charlie and Delta)
weighing 16,000 to 30,000 tones and standing in 140 m deep water. Works will
start 2015 till 2016, the remaining topsides will be removed over the following
eight years
A new under construction vessel (Allseas) will do the works, with 382 m long and
124 m wide, will have a topsides lift capacity of 48,000 tonnes (53,000 short
tons) and a jacket lift capacity of 25,000 tonnes (27,500 short tons)
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THANK YOU
Haitham K. M. Mokhtar
+971-50- 1 2 4 6 8 10
Haitham.mokhtar@gmail.com
Business card available.
Please pick one and do not hesitate to contact me
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