1 petroleum engineering 406 floating drilling lesson 11b motion compensation
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Petroleum Engineering 406 Floating Drilling
Lesson 11b Motion Compensation
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Lesson 6B - Motion Compensation
Tensioners Heave Compensators Passive Motion Compensation Active and Semiactive Systems
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Motion Compensator
Principles ofOperation
Purpose:
Keep bit on bottom
with low bit weight change
Air pressure can support entire weight of drillstring. e.g. 200,000 - 40,000 = 160,000lbf. Reduce air press.
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Heave Compensation for Bit
We can compensate at Crown Block
or at Travelling Block
Example: Keep bit weight within 30% of average value.Hook load = 200,000 lbf. Avg. bit wt. = 40,000 lbf
Bit Weight must be kept within 0.3 * 40k = 12k lbf.
i.e. keep Hook load within 12/200 * 100% = 6% !!
How is that possible? Larger air tanks!
Rucker Heave Compensator
Dual Pistons- on the travelling block
Large air cylinders below deck
Flexible hoses
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Figure 7-9 Vetco dual piston Heave Compensator
L.P. hydraulic fluid throttled for damping
Piston balancing may be problem
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Western Gear Heave Compensator
Figure 7-10
Split travelling block
Hydraulically operated pistons can be locked in any position with remotely operated valves.
Air operated units must be mechanically locked in position because of compressible fluid in cylinders.
Single Piston Rod
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Crown Block Heave Compensator
AIR STORAGE
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