Heavy Wall Dp & Drill Collars

8/13/2019 Heavy Wall Dp & Drill Collars

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11/25/13 HEAVY WALL DP & DRILL COLLARS

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28. HEAVY WALL DP& DRILL COLLARS

28.1 HEAVY WALL DRILL PIPE

- Functions

Part of the Drilling String, Heavy Drill pipe has aunit weight in between Drill Pipe and Drill Collars.They are run between

Drill Collars and Drill Pipes to:

1. Create a gradual reduction of BHA rigiditybetween the two.

2. Reduce fatigue stress on the DP just above theDCs.

3. Reduce wall friction in vertical deep wells withhigh RPM.

HW DP dimensions are standardized by API 7Specifications.The relevant ISO standard is the 10407 Spec. ENIrequirements are defined by internal specification.

- HW Saves Rig Time by ReducingTrip Time

HWs stand back in the rack likeregular Drill Pipe
http://www.apirig.com/product30.htmlhttp://www.apirig.com/product32.html


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- Reducing wall friction In Deviated Well

Reducing wall friction in deviated wells, heavy wall DP gives better direction control in deviatedwells.


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- Dimensions

ENI requires that all HWDP connections must have appropriate bore back boxes features.

External Tool Joint diameter = same as regular Drill Pipe; Tool Joint length > regular Drill Pipe; Body thickness > regularDrill Pipe;

- Heavy Wall Drill Pipe by SMF


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28.2 DRILL COLLARSDrill collars are the components of the drill string that provide the weight on bit when drilling.They are thick-walled, hollow

tubulars machined from solid bars of steel (usually plain carbon) ornon-magnetic nickel-copper alloy or other non-

magnetic premium alloys.The outside diameter may be machined with helical grooves (spiral) to reduce the potential

contactsurface for differential sticking prevention.ENI requirements are defined by internal specification. Drill Collars

dimensions are standardized by API 7 Specifications.The ISO 10407 Spec. is actually a draft.

- DRILL COLLAR TYPES

- Smooth

- Spiral

"Eni Best Practices" policy requiresto use only "Spiral Drill Collars"instead of the "Smooth" type".


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- DRILL COLLAR CHARACTERISTICS

Sizes and Dimensions (API 7)

D.C. Connection Dimensions

Mechanical characteristics

- Sizes and Dimensions (API 7)

Drill Collars are furnished in the sizes and dimensions shown in table .


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- D.C. Connection Dimensions

All drill collars connections must have stress relieve/bore back features in conformance with API 7.


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- Mechanical characteristics


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- BENDING STRENGTH RATIO CALCULATION

- Calculation

- Optimal Bending Strength Ratio

Bending ratio is calculatedknowing the type of thread andmeasuring, at a specific pointshown in the picture, the ID

andOD.For every table of determined ID,with OD we can cross the threadline and see the strength ratio onthe horizontal

axis.


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- DRILL COLLAR THREADS FEATURES

- Treatments


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- Features

- Boreback box and pin stress features. Force loading on box and pin connections for reducingstress concentrations.- Low

torque features. Reduction of contact surface in order to reduce the make up torque on 8.5/8regular connections

- Low torque features. Reduction of contact surface in order to reduce the make up torque on 8.5/8 regular connections.

28.3 DRILL STEM SUBS

- Cross-over examples


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- Schematic drawings

- Float Valve Recess in Bit Subs


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Table 12 Float Valve Recess in Bit Subs

Diameter ofValveAssembly

Diameter ofFloatRecess

Length ofValveAssembly

API Reg. BitBox

Ather PopularConnections

DR +/ 1/64 0(D +/-

1/32)L Size

A +/-

1/16Size A +/- 1/16

3 1/8 3 5/32 10 - - NC38 14 1/4

3 5/32 3 1/2 8 5/164

1/212 13/16 NC44 13 1/16

3 21/32 3 11/16 12 - - NC46 16 3/4

3 7/8 3 29/32 9 3/45

1/214 3/4 NC50 14 1/2

4 25/32 4 13/16 11 3/46

5/8

17 5 1/2 IF 17

- - -7

5/817 1/4 5 1/2 FH 17

- - -8

5/817 3/8 NC61 17 1/2

5 11/16 5 23/32 14 5/88

5/820 1/4 6 5/8 IF 19 7/8

28.4 LIFT SUBS

- Lift Subs (Type D)


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28.5 INSPECTIONS

Hewi wate, Drill collars, Short Drill Collars, Stem Sibs shall be inspected according to API RP 7Gand API RP 5A5. Therelevant ISO standard is the 10407 Spec.ENI requirements are defined by internal specification.DS1 and NS2 are new

standardizations issued by independent body.

- DC Inspections from API RP7G

API RECOMMENED PRATICE 7G

13.4 DRILL COLLAR INSOECTION PROCEDURE

The following inspection procedure for used drill collars is recommended:

a. Visually inspect full length to determine obvious damage and overall condition.

b. Measure OD and ID of both ends.

Documents

Heavy Wall Dp & Drill Collars