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