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Diminished Drillpipe Capacity Diminished Drillpipe Capacity Due to Slip CrushingDue to Slip Crushing
Drilling Engineering Association (DEA)A Research Operations Forum
What We KnowWhat We Know
Reaching (Exceeding?) Limits– Materials– Equipment
W. ReinholdW. ReinholdWH SpiriWH Spiri(World Oil, Oct. 1959)(World Oil, Oct. 1959)
Hydraulic SlipsHydraulic Slips
Hydraulic Controlled Slips
Conventional SlipsConventional Slips
Conventional Drop in 3 Man SlipsModified to enhance integrity at high loads
Strain Gage PlacementStrain Gage Placement
Strain Gages Placed at Critical Load/Stress Points on Modified Conventional Slips
Wedding CakeWedding Cake
ID Measuring System3 sensors at 120°phase separation
1.6 MM Pound Load Frame1.6 MM Pound Load Frame
Sample Loaded in Load Frame
ResultsResults
Dimensional LocationsStrain Gage LocationsEvaluate Shape and Diameters Before and After Testing
ResultsResults
Slip Die Bite Marks at Toe of Slips
Landing StringsLanding StringsOD ID PPF WALL5 3.574 32.67 0.7135 3.500 34.01 0.750
5 1/2 4.000 38.01 0.7505 7/8 4.375 41.05 0.7506 5/8 5.625 32.67 0.5006 5/8 5.581 34.01 0.5226 5/8 5.375 40.00 0.6256 5/8 5.345 40.90 0.6406 5/8 5.125 47.05 0.7506 5/8 4.999 50.46 0.8136.906 5.000 60.59 0.953
New 6 5/8 DrillpipeNew 6 5/8 Drillpipe
Hexagonal IDMill Process
Neck down of ODNeck down of OD
OD DeformationMidway up the toe of the slips
Neckdown Neckdown of Drillpipeof Drillpipe
As Weight is Hung Off Plastic Deformation Occurs
Change in Internal Diameter by Load CycleChange in Internal Diameter by Load Cycle
-0.80%
-0.70%
-0.60%
-0.50%
-0.40%
-0.30%
-0.20%
-0.10%
0.00%850 900 1000 1050 1100 1150 1250 1300 1350 1400
Load Cycle Maximum (kips)
% C
hang
e in
ID
Cumulative Change in Internal DiameterCumulative Change in Internal Diameter
-4.00%
-3.50%
-3.00%
-2.50%
-2.00%
-1.50%
-1.00%
-0.50%
0.00%
800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450Load (kips)
% C
hang
e in
ID
DRIFT
What We ThinkWhat We Think
This problem should not be ignoredIf the string needs to be held for a length of time, plastic deformation will cause the drillpipe to neckdown just below the slipsThe reduction in area will eventually weaken the drillpipe causing the pipe to part just below the slips
What Needs to be DoneWhat Needs to be Done
Comprehensive Studies to Better Define– Material Degradation– Material Limits– Equipment Operating Limits
Test validity of Spiri-Reinhold EquationPossible solutions– Mitigate Risks– Improve Cost Effectiveness
How?How?
Develop a study protocol that does not have the objective of qualifying a productStrain Gage OD and ID of Drill Pipe– ID Problematic
Precise, Repetitive, and Accurate Placement– Technically Difficult
Establish Control ValuesEstablish Control Values
Limit Scope– Limit variables– Establish baseline values
Determine generic damage to drill pipe
Limit Initial Study Limit Initial Study 66--12 Months12 Months
1 pipe vendor– Before tool joint
10 foot lengths– 5”– 5 ½”– 6 5/8”
2 Slip Styles– Narrow Column Inserts– Wide Column Inserts
New Solid Bowl inside new bushing – Establish control values– Split bowls more popular
Less consistentMore variance
Future Efforts Future Efforts –– Phase IIPhase II
Determine correlation between laboratory conditions vs rig conditions
Future Efforts Future Efforts –– Phase IIIPhase III
1 Drill Pipe vs Split Bowl vs Bushing– Split Bowl vs Bushing Condition Matrix
New x NewNew x Mid API SpecNew x Max API SpecMid API Spec x NewMax API Spec x NewMid API Spec x Mid API SpecMid API Spec x Max API SpecEtc.
Future Efforts Future Efforts –– Phase IVPhase IV
Establish Realistic Range– Coefficient of Friction
Water Base Mud vs Oil Base Mud– Insert Die and Slip Body– Slip Body and Bowl
Define Critical Damage to Drill Pipe– Inspection Criteria
Effect of Instantaneous Loading
Projected Cost Projected Cost –– Phase IPhase I
Lab and Engineering 100,000$ Drill Pipe 20,000$ Slips and Bowls Rental 10,000$ Bushing Rental 10,000$
TOTAL 140,000$
Safe and TroubleSafe and Trouble--free Operationsfree Operations
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