Pdc Bits.pdf

PDC Bit Structure

API Connection Shank Identification Slot

Breaker Slot Weld Blank

Crown Chamfer Matrix Bit Body Gauge Pad Nozzle Cutters Copyright Baker Hughes, Inc.

PDC Face View

Blade Junk Slot

Cutters

Nozzle

Copyright Baker Hughes, Inc.

PDC graphite mold assembly

Top Funnel

Blank Mid Funnel

Boat

Copyright Baker Hughes, Inc.

Diamond Bit Materials  The Bit Body  Matrix Body  Manufactured with a cast, graphite mold  Bit body made up of tungsten carbide matrix powder  Bonded together with a copper alloy binder  Very resistant to erosion and abrasion

Copyright Baker Hughes, Inc.

PDC Cutter Attachment

 Low temperature braze  Bonds only to PDC substrate  Technique is a critical skill

Copyright Baker Hughes, Inc.

Steel Body  Two piece design

Copyright Baker Hughes, Inc.

Diamond Bit Materials  The Bit Body  Milled from bar Stock Steel  Steel body design uses a cast steel body welded to a shank (two

piece design)

Copyright Baker Hughes, Inc.

Hardfacing

Oxy Acetylene Applied Macro Hardfacing Copyright Baker Hughes, Inc.

Shank

 High alloy, heat treated steel

(4140)  API regular connection  Breaker slots  Identification slots

Copyright Baker Hughes, Inc.

Steel Blank  Steel “skeleton” of a

matrix body bit

 The tungsten carbide

matrix is cast around the blank

 Provides for

attachment of the shank

 Soft, ductile steel

(1018)

Blank Copyright Baker Hughes, Inc.

Bit Body - Major Components

Shank

Steel Blank

Matrix Body

Copyright Baker Hughes, Inc.

Nozzles

 Sintered tungsten carbide

MSP

 Standard size is the “SP” (Single

Piece)

SP

 Additional size developed for

smaller bits is the “MSP” (Micro SP)

Copyright Baker Hughes, Inc.

Diamond Cutting Structures

Natural Diamond PDC

TSP

Impregnated Copyright Baker Hughes, Inc.

Polycrystalline Diamond Compact (PDC)

Man-Made Diamonds

• 1976, introduction of first PDC for drilling in petroleum and mining •Stratapax • A natural diamond is a single crystal, the term polycrystalline means many crystals

Copyright Baker Hughes, Inc.

PDC Cutter Manufacture

 Pre-made synthetic diamond  Pre-made tungsten carbide substrate  High Temperature High Pressure (HTHP) process Copyright Baker Hughes, Inc. Pictures courtesy of US Synthetic

Polycrystalline Diamond Compact (PDC)

Man-Made Diamonds

Diamond Table 0.010 in.

0.016 in.

Tungsten Carbide Substrate

45º Edge Chamfer

Copyright Baker Hughes, Inc.

PDC Cutter Properties  Diamond Table  Abrasion and impact resistance

 Diamond/Carbide Interface  Affects impact resistance

 Edge Geometry  Influences impact resistance

Copyright Baker Hughes, Inc.

Polished Cutters  Standard feature  Low Coefficient of Friction  Conventional PDC  Brake pads  Polished PDC  Ice on ice

 Hughes Christensen Patent

Copyright Baker Hughes, Inc.

Cutting Mechanics

Copyright Baker Hughes, Inc.

Definition - Depth of Cut (DOC)

 The depth the cutter is indented into the rock  Can be used along with RPM and a units constant to

determine rate of penetration:

 ROP (ft/hr) = DOC (in) x RPM (rev/min) x 5  ROP (m/hr) = DOC (mm) x RPM (rev/min) x 0.06

Depth of Cut

Example: 0.150” DOC, 100 RPM ROP (ft/hr) = 0.150” x 100 x 5 = 75 ft/hr

Copyright Baker Hughes, Inc.

Depth of Cut Questions

 If we speed up the RPM while maintaining the same depth of cut, what will happen to the ROP?  ROP will increase

 If we slow down the RPM but maintain the same ROP, what will happen to the DOC?  The DOC has to increase

Copyright Baker Hughes, Inc.

PDC Cutter Size vs. ROP

Cutter Size

Max. ROP (ft/hr) 100 RPM

180 RPM

0.323” (8.2 mm)

81

146

0.529” (13.3 mm)

133

240

0.750” (19.1 mm)

188

338

0.323” (8.2 mm)

0.162” x 100 RPM x 5 = 81 ft/hr

0.529” (13.3 mm)

0.265” x 100 RPM x 5 = 133 ft/hr

0.750” (19 mm)

0.375” x 100 RPM x 5 = 188 ft/hr Copyright Baker Hughes, Inc.

Cutter Orientation- Back Rake

15º

20º

30º

 Determines the aggressiveness of the cutter  The lower the back rake, the more aggressive the cut

Copyright Baker Hughes, Inc.

Cutting Efficiency - Backrake

 Generally, smaller backrake angles require less weight and

torque  The magnitude of the effect depends on rock strength

Copyright Baker Hughes, Inc.

Decreasing Backrake Increases Efficiency Medium Shale, Co = 10 kpsi Specific Energy vs. Penetration Rate 0.016 in. x 45 o , Mancos, 3 kpsi

Specific Energy (psi)

100,000

15 deg

90,000

20 deg

80,000

30 deg

70,000

40 deg

60,000 50,000 40,000 30,000 20,000

Increasing WOB

10,000 0 0

20

40

60

80

100

120

140

Penetration Rate (ft/hr)

Copyright Baker Hughes, Inc.

Can we just use small chamfers and 15º BR?  Based on our current technology,

the answer is NO

 In part, because durability would

suffer

 Also, because low backrakes affect

wearflat development

 For a given wear state, lower backrakes yield bigger wearflats

25º

15º

10º Copyright Baker Hughes, Inc.

PDCWear Predictions: New vs. Worn Even cooling Full carbide support 120 RPM

Specific Energy vs. Wear 084 G445XL Variants

160,000 15 deg BR

Specific Energy (psi)

140,000

20 deg BR 30 deg BR

120,000

30% Worn

40 deg BR 100,000 80,000 60,000

New Condition

40,000 20,000 0 0

100

200

300

400

500

600

700

Distance Drilled (ft)

Low backrakes are more efficient in the “new” state As bits wear they can become less efficient Copyright Baker Hughes, Inc.

Introduction to Bit Profiles  The term “profile” or “crown profile” refers to the

distinctive shape of the bit head when viewed from the side

 A variety of profile shapes and lengths are used to

optimize bit performance depending on the bit type and application

 The basic objective of any profile is to optimize bit

stabilization and wear as well as achieve well bore trajectory objectives

Copyright Baker Hughes, Inc.

The PDC Bit Profile

0,0,0 Point

Gauge Length

Bit Center Line

 Bit profile and cutter layout

are closely related. Each cutter layout is compromise between the following:  Maximum number of cutters

(longer bit life)

 Lowest blade count (better

hydraulics, ROP)

Nose Location

Shoulder

Cone Angle Nose Radius

Nose

 Shortest possible profile (better

bit stability / cleaning)

Cone

Copyright Baker Hughes, Inc.

PDC Profile Types

Short Parabolic

Shallow Cone

Long Parabolic

Copyright Baker Hughes, Inc.

Secondary Stability

BRUTE Inserts  Acronym for “Backups that are Radially

Unaggressive and Tangentially Efficient”

 A thick diamond table cutter is embedded in

a wear knot and oriented so that it can cut tangentially, but not radially (sideways)  Polished diamond provides a “low friction wear knot”  Orientation allows BRUTE to do work if leading cutter is damaged  Recessed 0.100”

Copyright Baker Hughes, Inc.

BRUTE Inserts in the Cone Backups that are Radially Unaggressive and Tangentially Efficient

 Provides a bearing that limits depth of cut for steerability

(Reduced Exposure concept)  Increased durability

 Repairable Reduced Exposure feature Copyright Baker Hughes, Inc.

Dynamics Summary

 Primary Stability

 Secondary Stability

 The ability of a bit to drill

 The magnitude of vibration when

 Inter-related with system

 Controlled by chordal drop

 Primarily controlled by

 Also controlled by external

smoothly stability

cutter layout

unstable

management (standard) features:

 LMM (standard)  Wear Knots/Clouds (option)  BRUTES (option)

Copyright Baker Hughes, Inc.

Hydraulic Efficiency

 Cuttings Removal (“Cleaning”)  The effectiveness of each layout is determined through

laboratory tests in sticky shale under fixed conditions  Maximum ROP without balling

 Cutter Cooling  Keep the velocity of drilling fluid within an acceptable

range at the face of each cutter along each blade

Copyright Baker Hughes, Inc.

Computational Fluid Dynamics Maximize ROP  Minimize Particle

Minimize Erosion  Control Fluid Velocity

Residence Time

 Balanced Flow  Minimize Re-circulation

Copyright Baker Hughes, Inc.

Particle Residence Time Simulation

Poor evacuation -- cuttings are forced to center of bit

Good cuttings evacuation

Copyright Baker Hughes, Inc.

Balanced Flow

Original Nozzle Orientation

Optimized Orientation Flow Comparison

Flow Comparison 1.4

%Flow/%Cuttings

%Flow/%Cuttings

2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0

1.2 1.0 0.8 0.6 0.4 0.2

1

2

3

4

5

6

Junk Slot #

0.0

1

2

3

4

5

6

Junk Slot #

Reverse Flow

Copyright Baker Hughes, Inc.

CFD Optimization – Lab Results 8¾” HC406 E0430

E0369

Flow Rate Comparison

3.5

E0369 % Flow / % Cuttings

3.0

E0430 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 1

2

3

4

5

6

Junk Slot No. Copyright Baker Hughes, Inc.

Simulator Results: 8¾” HC406 E0369

Max ROP of 270 ft/hr Balled and dropped to 200 ft/hr

E0430

Max ROP of 290 ft/hr* Field ROP consistent with lab results *Simulator limit Copyright Baker Hughes, Inc.

Gauge

 The stabilizing section of the bit Copyright Baker Hughes, Inc.

Matrix Body Gauge

 Round or cube Natural Diamonds  TCI bricks  TSP Copyright Baker Hughes, Inc.

Steel Body Gauge

PDC In Gauge TCI Compacts PDC Cutters

Standard Gauge

Premium Gauge

Copyright Baker Hughes, Inc.

PDC Gauge Option



In-gauge PDC cutters



Flush mounted on leading edge



Extra durability for applications that prematurely wear a conventional TCI/ND gauge

Copyright Baker Hughes, Inc.

Spiral Gauge Pads

 Used primarily on low blade count (<5) designs  Used to manage chordal drop Copyright Baker Hughes, Inc.

Updrill Options

Natural Diamond

PDC

Copyright Baker Hughes, Inc.

Genesis Nomenclature

HC R/M X XX S Z X Product Line Steerable Type

Blade Steel Zenith Back Up Count Body Cutters Cutters

(R = Rotary Steerable) Cutter Size (M = Motor Steerable) (eighths of an inch)

Example: HC607ZX



“HC” - Genesis product line



“6” - ¾” (19mm) cutter size



“07” - 7 blades



“Z” - Zenith



“X” - backup Cutters

Copyright Baker Hughes, Inc.

Example: 12 ¼” HCM606

Copyright Baker Hughes, Inc.