pete 406 lesson 8 offshore drilling. content inland barges (submersible) jackup rigs –wildcats...
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PETE 406
Lesson 8
Offshore Drilling
Content
• Inland barges (submersible)
• Jackup rigs– Wildcats– Shallow water templates– Cantilevered over platform
• Platform rigs
• Floaters - semi’s and drillships
Inland barge
• Used in swamps, bays, inland water, shallow offshore.
• Floated and towed to location
• On location these rigs are submerged
• Well is drilled
• Personnel and supplies are brought in by boat.
Jackup rigs
Noble Drilling’s
Cecil Forbes
A Jack-Up Rig
Jackup rigs
• Independent legs or mat supported
• Some are self propelled to location, but most moved by tugs
• On location survey boat surveys location
Jackup rigs
• Legs jacked down to sea floor
• Hull picked up above water
• Rig “pre-loaded”
• Seawater pumped out
• Jacked up to working “air gap”
• Well drilled
Jackup rigs
• Used for both wildcat and development
• Shallow water up to 350-400’ WD
• Derrick may be fixed or cantilevered
Platform rigs
• Tendered
Platform Rig
• Self contained
Platform Rig
• Operations similar to land except:– Limited storage space– Crew lives on location– Cementing operations simpler
Floating rigs
• Semi-submersible
• Drill ships
Sonat’s George Washington
A Semi-Submersible
Rig
Zapata’s Trader
A Drillship
Semi-submersible
Marine Riser
Subsea BOP stack
Drilling from Floating Vessel
• Rig move– Hole opener pulled
from storage and prepared for use
– Structural casing is measured and brought on deck
– Inspect and test riser and BOP system
Drilling from Floating Vessel
– Water depth at new location verified– Tide tables obtained– Choke manifold inspected and tested
• Site surveyed and marked with buoys
Drilling from Floating Vessel
• Anchor boats on location
• Heading adjusted and anchor setting begins
Drilling from Floating Vessel
Drilling from Floating Vessel
• Anchor lines tensioned
Drilling from Floating Vessel
• Well prepared for spudding– Temporary guide base
(A) set
– 36” Structural hole drilled to 80’ to 200’ BML
– 30” Structural casing (B) run and cemented with permanent guide base (C) attached
AB
C
k
• 26” Conductor hole drilled to approx. 1000’ BML– Can be
drilled with or without riser
– 20” conductor casing run and cemented.
lling
• Wellhead installed with conductor casing
While WOC riser and stack are N/U and latched onto the wellhead
Control pods
Surface hole drilled to 3000’ to 5000’ BML
Surface casing is run and cemented through riser and BOP’s
Floating Drilling
• Float collar drilled out and casing tested
• Float shoe drilled out and 5’ to 15 feet of new formation drilled
• Hole is circulated and conditioned
• Casing seat is tested
Intermediate hole drilled to just above target zone and logged
Intermediate casing set, cemented and tested
Intermediate casing drilled out
Hole circulated and conditioned
Casing seat tested
Production hole drilled to TD and logged
Production casing or liner run and cemented
Well completed and tested
Floating Drilling
• After testing, hole prepared for abandonment– P&A, PNA– TA, T&A, TNA
• Perfs squeezed, and cement plugs set according to regulatore rules and regulations
Floating Drilling
• Riser and BOP retreived
• Casing cut approx. 10’ BML if PNA
• Temporary and permanent guide base retrieved
• Anchors pulled
• Vessel under way to next location
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