1 petroleum engineering 406 floating drilling lesson 11a motion compensation
TRANSCRIPT
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Petroleum Engineering 406Floating Drilling
Lesson 11a Motion Compensation
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Lesson 6 - Motion Compensation
ReentryTensioners Heave Compensators Passive Motion Compensation Active and Semiactive Systems
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Re-entry
It is possible to re-enter a borehole without using guidelines!
1. Use land-based navigation equipment to get the vessel in the vicinity of the well
or better still: Use GPS (Global Positioning System)
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Re-entry, cont’d
2. Lower reentry string to a safe distance above the wellhead
3. Use position location equipment to complete the job:
(i) Television camera
(ii) Acoustic device - pinger or transponder (iii) ROV - Remote Operated Vehicle
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Heave Compensation
How do you maintain a constant tension on the marine riser - when the vessel
heaves?
How do you maintain a constant weight on the bit - when the vessel heaves?
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Deadweight Riser Tensioning System
Dead Weight(~constant
tension)
Dead Weight
Slip Joint
Marine Riser
Early design - OK up to 100,000 lbf. Attached to lower half of telescoping joint. Adds weight & is bulky...
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Pneumatic Riser Tensioning System
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Pneumatic/Hydraulic Heave Compensation System
Pneumatic/Hydraulic Tensioners:
Take up much less roomFacilitate changing the tension by changing the air pressureCan be used for the marine riser,
the guidelines and the drill string
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Pneumatic/Hydraulic Heave Compensation System
Passive Systems are the most popularRequire essentially no energy inputUse an “air spring” with a variable spring constantCan keep the tension within ~ 15%
or even less.
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Pneumatic/Hydraulic Heave Compensation System
Active SystemsRequire external energy through each load cycleProvides a highly consistent forceBut -- Has a high initial costHas a high operating cost
11Lower sheaves are attached to the cylinder (and vessel), upper sheaves are attached to the piston rod
20 ft
5 ft1,500 psig WP
TypicalTensioner