Hydraulic Adjustable Stabilizers for Directional and Horizontal Wells

Description

Goldenman ZBW Hydraulic Variable Gauge Stabilizers provide controllable bottom-hole-assembly stabilization during directional, horizontal and extended-reach drilling.

Unlike a conventional fixed-gauge stabilizer, the ZBW stabilizer uses drilling-fluid differential pressure to extend multiple wear-resistant support heads toward the borehole wall.

During circulation, the support heads extend and establish the required stabilization diameter. When circulation stops, the heads retract toward the tool body, reducing the external diameter for tripping and lowering the risk of drag, tight-hole resistance and mechanical sticking.

The standard Goldenman range includes:

• ZBW 8-1/2 in Hydraulic Variable Gauge Stabilizer
• ZBW 8-3/4 in Hydraulic Variable Gauge Stabilizer
• NC50 Box × NC46 Pin configuration
• NC50 Box × NC50 Pin configuration
• 15-head radial support system
• Maximum working pressure of 20 MPa
• Maximum allowable differential pressure of 40 MPa
• Radial support force of 513 kN at 10 MPa differential pressure
• High-strength alloy-steel pressure body
• Wear-resistant tungsten-carbide support surfaces
• Standard and high-temperature sealing packages
• Directional, horizontal and extended-reach drilling configurations
• Custom connection, gauge and hydraulic-response options

Product Short Description

Goldenman Hydraulic Variable Gauge Stabilizers use drilling-fluid differential pressure to extend multiple support heads and centralize the BHA during drilling.

When the mud pumps stop, the support heads retract and reduce the tool’s running diameter. This allows the stabilizer to pass more smoothly through tight sections, doglegs, ledges and locally under-gauge intervals.

The stabilizer can be positioned near the bit, between Drill Collars or within a rotary-steerable or motor BHA. Its effect on build, hold or drop tendency is determined by stabilizer position, expanded gauge, BHA stiffness, bit-to-stabilizer distance and drilling parameters.

Product Highlights

• Hydraulic variable-gauge stabilization
• Differential-pressure-activated support heads
• Automatic retraction after pump shutdown
• ZBW 8-1/2 and ZBW 8-3/4 models
• 15 radial support heads
• Minimum extension pressure of 0.1 MPa
• Maximum working pressure of 20 MPa
• Maximum differential pressure of 40 MPa
• 513 kN radial support force at 10 MPa differential pressure
• NC50 Box × NC50 Pin option
• NC50 Box × NC46 Pin option
• Compact 1,350 mm overall length
• 55 mm internal flow bore
• High-strength alloy-steel body
• Wear-resistant support-head surfaces
• Replaceable hydraulic seals and internal components
• Full-flow drilling-fluid passage
• Reduced tripping OD after retraction
• Improved BHA centralization
• Directional and horizontal drilling capability
• Build-, hold- and drop-angle BHA applications
• Reduced torque, drag and lateral vibration
• Reduced risk of stabilizer hang-up
• API 7-1 stabilizer manufacturing configuration
• API 7-2 rotary-shouldered connections
• Material and heat-number traceability
• UT, MPI and dimensional inspection
• Hydraulic function and pressure testing

General Technical Specifications

Parameter	Available Specification
Product	Hydraulic Variable Gauge Drilling Stabilizer
Series	ZBW
Product category	Bottom-Hole-Assembly Stabilizer
Applicable product standard	API Spec 7-1
Connection standard	API Spec 7-2
Standard models	ZBW 8-1/2 in and ZBW 8-3/4 in
Operating principle	Differential-pressure hydraulic actuation
Support-head quantity	15
Minimum extension differential pressure	0.1 MPa
Radial support force	513 kN at 10 MPa differential pressure
Maximum working pressure	20 MPa
Maximum allowable differential pressure	40 MPa
Internal flow bore	55 mm
Overall length	1,350 mm
Top connection	NC50 Box
Bottom connections	NC46 Pin or NC50 Pin
Main body material	High-strength alloy steel
Wear protection	Tungsten-carbide hardfacing or carbide inserts
Seal materials	HNBR, FKM and high-temperature elastomers
Service	Vertical, directional and horizontal drilling
Supply	Complete tool, repair kits and replacement support heads

ZBW Model Specifications

Parameter	ZBW 8-3/4 in	ZBW 8-1/2 in
Body OD	201 mm	204 mm
Internal bore	55 mm	55 mm
Support-head diameter	80 mm	80 mm
Number of support heads	15	15
Overall length	1,350 mm	1,350 mm
Top connection	NC50 Box	NC50 Box
Bottom connection	NC50 Pin	NC46 Pin
Variable outside diameter	211–213 mm	214–215 mm
Minimum extension pressure	0.1 MPa	0.1 MPa
Radial force at 10 MPa differential	513 kN	513 kN
Maximum working pressure	20 MPa	20 MPa
Maximum allowable differential pressure	40 MPa	40 MPa

The final model designation, body diameter, expanded gauge and connection combination are supplied according to the approved BHA drawing.

What Is a Hydraulic Variable Gauge Stabilizer?

A Hydraulic Variable Gauge Stabilizer is a drill-string component whose external stabilizing diameter changes in response to drilling-fluid pressure.

The tool contains:

• A central pressure body
• Full-flow internal bore
• Hydraulic pressure passages
• Axially or radially actuated piston system
• Multiple movable support heads
• Return mechanism
• Hydraulic seals
• Wear-resistant gauge surfaces
• Top and bottom rotary-shouldered connections

When differential pressure reaches the activation level, hydraulic force moves the support heads outward.

The extended heads contact or approach the borehole wall and provide lateral support for the BHA.

When the pumps stop and hydraulic pressure falls, the return system retracts the heads toward the body.

Operating Principle

Pump-Off Condition

When the mud pumps are stopped:

• Internal differential pressure falls
• Hydraulic force is removed
• Support heads retract
• External running diameter decreases
• Tool contact with the borehole wall is reduced

This condition supports:

• Running into the hole
• Pulling out of the hole
• Passing through doglegs
• Passing through locally under-gauge intervals
• Reducing mechanical resistance
• Reducing the risk of hanging up

Pump-On Condition

When drilling-fluid circulation begins:

1. Mud enters through the upper connection.
2. Fluid flows through the central bore.
3. A controlled pressure differential develops across the hydraulic actuation system.
4. Hydraulic force acts on the piston or support-head mechanism.
5. The support heads move radially outward.
6. The stabilizer reaches its designed operating diameter.
7. Radial force supports the BHA against lateral movement.

Pressure Increase

As differential pressure increases, the hydraulic mechanism produces greater support force within the tool’s working envelope.

The ZBW series produces a radial support force of 513 kN at a 10 MPa differential pressure.

Pump Shutdown

When circulation stops:

1. Hydraulic differential pressure decreases.
2. The piston returns to its initial position.
3. The support heads retract.
4. The effective stabilizer diameter decreases.
5. The tool can be tripped through the wellbore with reduced wall contact.

Variable Gauge Stabilizer vs Fixed Stabilizer

Feature	Hydraulic Variable Gauge Stabilizer	Integral Blade Stabilizer
Stabilizing diameter	Changes hydraulically	Fixed
Drilling condition	Support heads extended	Blades remain at fixed OD
Tripping condition	Heads retract	Fixed OD remains unchanged
Activation	Drilling-fluid differential pressure	Mechanical borehole contact
Internal components	Hydraulic mechanism and seals	Solid forged body
Tight-hole passage	Improved through reduced running OD	Controlled by fixed under-gauge clearance
Maintenance	Hydraulic and mechanical inspection	Gauge and hardfacing inspection
Main application	Directional wells with variable clearance	General vertical and directional drilling
Main advantage	Adjustable contact and reduced trip resistance	Simplicity and durability

Variable Gauge Stabilizer vs Underreamer

A Hydraulic Variable Gauge Stabilizer is designed primarily to stabilize and centralize the BHA.

An Underreamer is designed to cut and enlarge the borehole beyond the pilot-bit diameter.

The ZBW Stabilizer:

• Uses wear-resistant support heads
• Applies radial support
• Controls BHA position
• Does not rely on cutting structures to enlarge the formation
• Retracts for tripping

It should not be specified as a hole-opening tool unless the approved design includes qualified cutting elements.

Variable Gauge Stabilizer vs Casing Centralizer

A drilling Stabilizer and a Casing Centralizer perform different functions.

Drilling Stabilizer	Casing Centralizer
Installed in the rotating BHA	Installed on casing
Used while drilling	Used while running and cementing casing
Controls BHA lateral movement	Maintains casing standoff
Carries torque and drilling-fluid pressure	Normally does not transmit drilling torque
Uses rotary-shouldered connections	Installed over or between casing joints
Manufactured as a drill-stem element	Manufactured as cementing equipment

The correct product name for this page is Hydraulic Variable Gauge Drilling Stabilizer, not Drill Pipe Centralizer.

BHA Placement

The hydraulic stabilizer can be installed:

• Immediately above the bit
• Above a Downhole Motor
• Between Drill Collars
• Between Heavy Weight Drill Pipe sections
• Within a packed BHA
• Within a pendulum BHA
• Near an MWD or LWD assembly
• Within a Rotary Steerable System BHA

The correct location depends on the required directional response.

Near-Bit Placement

A stabilizer positioned close to the bit provides strong lateral support at the lower BHA.

It can:

• Improve bit stability
• Reduce bit whirl
• Reduce borehole spiraling
• Reduce lateral bit movement
• Improve hole-size consistency
• Support hold-angle or build-angle assemblies
• Improve toolface stability during sliding

The effect depends on bit-to-stabilizer spacing, gauge diameter and BHA stiffness.

String Stabilizer Placement

A String Stabilizer is installed farther above the bit between Drill Collars or other BHA components.

It can:

• Centralize the Drill Collar section
• Reduce lateral vibration
• Control bending distribution
• Reduce collar-to-wall contact
• Improve weight transfer
• Support trajectory control
• Reduce local BHA wear

Multiple stabilizers can be used in a packed BHA.

Build-Angle BHA

A fulcrum-type BHA places a stabilizer near the bit with selected spacing to the next contact point.

The arrangement creates a bending tendency that can increase inclination.

Build tendency is controlled by:

• Near-bit stabilizer position
• Expanded stabilizer gauge
• Drill Collar stiffness
• Bit-to-stabilizer distance
• Weight on bit
• Rotary speed
• Formation response
• Motor bend setting

The stabilizer does not independently guarantee a specific build rate. The complete BHA geometry determines the resulting dogleg severity.

Hold-Angle BHA

A packed BHA uses multiple near-full-gauge stabilizers to resist lateral bending.

It provides:

• Improved directional stability
• Reduced unwanted inclination change
• Reduced borehole tortuosity
• Improved hole quality
• Reduced BHA vibration
• More stable rotary drilling

The Hydraulic Variable Gauge Stabilizer can be extended during drilling and retracted during tripping.

Drop-Angle BHA

A pendulum BHA positions the first major stabilizing point farther above the bit.

Gravity and BHA bending create a tendency to reduce inclination.

The hydraulic stabilizer can be placed according to the required pendulum length and directional program.

Directional Drilling Applications

Goldenman ZBW Stabilizers are used in:

• Directional oil wells
• Horizontal wells
• Extended-reach wells
• Sidetrack wells
• Build sections
• Tangent sections
• Drop sections
• Rotary drilling
• Slide drilling
• Motor BHAs
• Rotary Steerable System BHAs
• High-dogleg well profiles
• Wells with tight or irregular hole sections
• Wells with repeated tripping difficulty

Horizontal Well Applications

Horizontal wells create increased contact between the BHA and the low side of the borehole.

The stabilizer helps:

• Centralize the lower BHA
• Control lateral movement
• Reduce Drill Collar wear
• Improve weight transfer
• Reduce vibration
• Improve toolface control
• Maintain the planned trajectory
• Reduce excessive borehole enlargement

The retractable design reduces external contact when the pumps are stopped for tripping.

Extended-Reach Applications

Extended-reach wells create high torque and drag due to long inclined and horizontal intervals.

A correctly configured variable-gauge stabilizer supports:

• Reduced wall contact during trips
• Improved weight transfer during drilling
• Controlled BHA centralization
• Improved hole cleaning around the BHA
• Reduced risk of stabilizer hang-up
• Stable directional response

Hydraulics, equivalent circulating density and pressure losses are evaluated together with the activation requirement.

Tool Construction

Main Body

The main body provides:

• Structural strength
• Internal pressure containment
• Rotary torque transmission
• Axial-load transmission
• Hydraulic flow path
• Support-head guide locations
• Top and bottom connections

The body is manufactured from forged high-strength alloy steel and receives controlled heat treatment.

Support Heads

The support heads provide the primary borehole contact.

They are designed for:

• Radial movement
• High contact load
• Abrasive formation exposure
• Repeated extension and retraction
• Gauge retention
• Drilling-fluid circulation around the body

Wear surfaces use tungsten-carbide hardfacing, inserts, tiles or project-specific carbide systems.

Hydraulic Piston

The hydraulic piston converts drilling-fluid differential pressure into mechanical movement.

The piston system controls:

• Extension pressure
• Support-head travel
• Radial force
• Return movement
• Pressure isolation

Return System

The return mechanism retracts the support heads after the pressure differential is removed.

It can include:

• Mechanical springs
• Hydraulic balancing
• Cam surfaces
• Return sleeves
• Combination return mechanisms

Sealing System

Hydraulic seals isolate the actuation chambers from drilling-fluid leakage.

Available materials include:

• HNBR
• FKM
• High-temperature elastomers
• Abrasion-resistant polymer seals

Seal selection is based on temperature, mud type, pressure, chemical additives and expected circulation time.

Main Body Material

The standard body uses high-strength quenched-and-tempered alloy steel.

Available material configurations include:

• AISI 4145H Modified
• Equivalent drill-stem alloy steel
• Sour-service-controlled material
• High-toughness low-temperature material
• Non-magnetic material for selected directional assemblies

The body material provides:

• High tensile strength
• High torsional capacity
• Impact toughness
• Fatigue resistance
• Stable heat-treatment response
• Resistance to drilling shock and vibration

Non-Magnetic Configuration

A non-magnetic stabilizer configuration is used near:

• MWD tools
• LWD tools
• Magnetometers
• Directional survey instruments
• Formation-evaluation equipment

Non-magnetic material reduces local magnetic interference that can affect directional measurements.

The finished tool undergoes magnetic-permeability and magnetic-field inspection according to the project specification.

Wear Protection

Support-head wear protection can include:

• Crushed tungsten-carbide hardfacing
• Tungsten-carbide inserts
• Carbide tiles
• Carbide blocks
• Spray-applied carbide coating
• Nickel-based carbide matrix
• Gauge-edge reinforcement

The hardfacing system is selected from:

• Formation abrasiveness
• Expected run length
• Rotary speed
• Support-head contact pressure
• Mud solids
• Casing-friendly requirements
• Repair strategy
• Maximum permitted gauge wear

Open Flow Paths

The stabilizer body and support-head arrangement maintain open flow paths for drilling fluid and cuttings.

The flow-path design supports:

• Cuttings transport
• Reduced packing
• Reduced pressure loss
• Reduced solids accumulation
• Mud circulation around the BHA
• Cleaning of the support-head mechanism

Flow area is matched to the drilling-fluid rate, rheology, solids loading and required hydraulic activation pressure.

Drilling-Fluid Compatibility

Available sealing and material packages support:

• Water-Based Mud
• Oil-Based Mud
• Synthetic-Based Mud
• High-salinity drilling fluids
• Weighted drilling mud
• High-solids systems
• High-temperature mud systems

The quotation identifies:

• Mud base
• Mud density
• Chloride concentration
• Oil-water ratio
• Solids concentration
• Maximum temperature
• Chemical additives

Rotary-Shouldered Connections

Standard connection options include:

• NC46
• NC50
• Project-specific NC connections
• API Regular connections
• IF connections
• Customer-specified rotary-shouldered connections

The current ZBW models use:

• NC50 Box × NC50 Pin
• NC50 Box × NC46 Pin

Connection inspection covers:

• Thread form
• Taper
• Lead
• Pitch diameter
• Thread height
• Shoulder flatness
• Shoulder perpendicularity
• Box counterbore
• Pin nose
• Connection concentricity
• Surface finish

Stress-Relief Features

Pin stress-relief grooves and box borebacks are available according to the selected connection and BHA fatigue requirements.

Stress-relief features reduce fatigue concentration near the last engaged thread.

The connection design balances:

• Fatigue resistance
• Torsional capacity
• Tensile capacity
• Pin internal diameter
• Connection geometry
• BHA loading

Stabilizer Gauge Selection

The operating gauge is selected from:

• Bit diameter
• Nominal hole size
• Required under-gauge clearance
• Well trajectory
• Formation stability
• Hole enlargement tendency
• Expected gauge wear
• Trip-clearance requirement
• Directional response
• BHA placement

A fixed stabilizer is commonly selected at or slightly below bit gauge.

A hydraulic variable-gauge stabilizer requires both:

• A retracted running diameter
• An expanded operating diameter

Both dimensions must be included in the BHA clearance analysis.

Hydraulic Selection

Hydraulic selection includes:

• Minimum pump flow rate
• Maximum pump flow rate
• Pump pressure
• Bit pressure drop
• Motor pressure drop
• MWD pressure drop
• Stabilizer activation pressure
• Stabilizer pressure loss
• Maximum differential pressure
• Mud density
• Mud rheology
• Nozzle configuration

The stabilizer must extend within the planned circulating range without consuming excessive hydraulic power or reducing bit cleaning.

Operating Procedure

Before Running

1. Verify model and serial number.
2. Verify top and bottom connections.
3. Measure retracted outside diameter.
4. Inspect all support heads.
5. Confirm free support-head movement.
6. Inspect the internal bore.
7. Inspect rotary-shouldered threads.
8. Verify seal and repair-kit configuration.
9. Complete a low-pressure extension test.
10. Complete a retraction test.
11. Install thread protectors until assembly.

BHA Makeup

1. Clean the pin and box connections.
2. Inspect sealing shoulders.
3. Apply approved rotary-shouldered thread compound.
4. Align the connected components.
5. Make up the connection using calibrated tongs.
6. Apply the specified makeup torque.
7. Record the BHA position and stabilizer orientation.
8. Confirm unrestricted internal flow.

Running in Hole

The tool is run with the support heads in the retracted condition.

Running practices include:

• Controlled tripping speed
• Monitoring hook load
• Monitoring drag trends
• Avoiding uncontrolled impact
• Circulating through tight sections when required
• Recording restriction depths
• Confirming pressure response before drilling

Activating the Stabilizer

1. Establish drilling-fluid circulation.
2. Increase flow at a controlled rate.
3. Observe standpipe-pressure response.
4. Reach the required activation differential pressure.
5. Confirm stable pressure behavior.
6. Begin drilling within the approved operating envelope.

Drilling

During drilling, monitor:

• Standpipe pressure
• Pump rate
• Torque
• Weight on bit
• Rate of penetration
• Toolface stability
• Vibration
• Cuttings return
• Hole cleaning
• Directional response

Tripping Out

1. Stop or reduce circulation according to the operating procedure.
2. Allow hydraulic pressure to decay.
3. Confirm support-head retraction.
4. Begin pulling at a controlled speed.
5. Monitor overpull and drag.
6. Circulate if abnormal resistance develops.
7. Avoid excessive force through known restrictions.

Maintenance After Each Run

After recovery:

• Wash the internal bore
• Flush hydraulic passages
• Remove drilling solids
• Inspect support-head movement
• Measure support-head wear
• Measure retracted and expanded OD
• Inspect carbide wear surfaces
• Inspect tool-body erosion
• Inspect seal areas
• Inspect return components
• Inspect pin and box threads
• Perform MPI on critical areas
• Replace damaged seals
• Function-test extension and retraction
• Pressure-test the repaired assembly

Common Failure Modes

Support Heads Fail to Extend

Possible causes include:

• Insufficient differential pressure
• Blocked hydraulic port
• Solids contamination
• Damaged piston
• Seal leakage
• Broken return or actuation component
• Incorrect assembly

Support Heads Fail to Retract

Possible causes include:

• Packed drilling solids
• Damaged return spring
• Scored guide surfaces
• Deformed support head
• Internal corrosion
• Excessive hardfacing damage
• Pressure trapped inside the actuation chamber

Excessive Pressure Loss

Possible causes include:

• Restricted internal bore
• Blocked flow passages
• Incorrect nozzle or hydraulic configuration
• Internal component movement
• Mud solids accumulation
• Seal extrusion

Rapid Gauge Wear

Possible causes include:

• Abrasive formation
• Excessive rotary speed
• High lateral loading
• Incorrect hardfacing
• Long rotating interval
• Poor hole cleaning
• Extended drilling in an under-gauge hole

Tool Hangs Up While Tripping

Possible causes include:

• Incomplete retraction
• Borehole ledge
• Keyseat
• Differential sticking
• Accumulated cuttings
• Under-gauge hole
• Damaged support head
• Excessive tripping speed

Connection Fatigue

Possible causes include:

• Incorrect makeup torque
• Damaged shoulder
• Thread wear
• Excessive dogleg severity
• High bending load
• Vibration
• Incorrect stress-relief geometry
• Repeated uncontrolled recutting

Manufacturing Process

Goldenman manufacturing includes:

1. Forged alloy-steel material verification
2. Heat-number assignment
3. Rough machining
4. Quenching and tempering
5. Mechanical-property testing
6. Ultrasonic examination
7. Internal-bore machining
8. Hydraulic-port machining
9. Support-head pocket machining
10. Piston and sleeve machining
11. Rotary-connection machining
12. Thread gauging
13. Support-head manufacturing
14. Carbide hardfacing application
15. Hardfacing inspection
16. Seal and hydraulic-component assembly
17. Dimensional inspection
18. Support-head travel inspection
19. Extension-pressure testing
20. Retraction testing
21. Differential-pressure testing
22. Pressure-hold testing
23. Radial-load verification
24. Final MPI
25. Surface coating
26. Permanent marking
27. Documentation review
28. Export packaging

Quality Control and Testing

Inspection and testing include:

• Chemical-composition verification
• Heat-treatment verification
• Yield-strength testing
• Tensile-strength testing
• Elongation testing
• Impact testing
• Hardness inspection
• Full-body ultrasonic testing
• Magnetic-particle testing
• Body OD and ID inspection
• Overall-length inspection
• Concentricity inspection
• Support-head dimension inspection
• Support-head quantity verification
• Hardfacing thickness inspection
• Carbide-bond inspection
• Thread-gauge inspection
• Shoulder inspection
• Minimum activation-pressure testing
• Maximum working-pressure testing
• Extension and retraction cycling
• Hydraulic leakage testing
• Internal flow testing
• Final visual inspection

Product Marking

Each stabilizer is permanently marked with:

• Goldenman identification
• Product type
• ZBW model
• Body outside diameter
• Variable-gauge range
• Internal bore
• Top connection
• Bottom connection
• Maximum working pressure
• Maximum differential pressure
• Heat number
• Serial number
• Manufacturing date

Product Documentation

The documentation package includes:

• Certificate of Conformity
• Product datasheet
• General assembly drawing
• BHA dimensional drawing
• Hydraulic schematic
• Material certificate
• EN 10204 3.1 certificate
• Chemical-composition report
• Heat-treatment record
• Mechanical-property report
• Hardness report
• Impact-test report
• Ultrasonic-test report
• Magnetic-particle-test report
• Thread-gauge inspection report
• Dimensional inspection report
• Hardfacing inspection report
• Hydraulic function-test report
• Extension and retraction test report
• Pressure-test report
• Material traceability list
• Operation and maintenance manual
• Recommended spare-parts list
• Packing list
• Third-party inspection report

Spare Parts and Repair Kits

Goldenman supplies:

• Support heads
• Carbide wear blocks
• Hydraulic pistons
• Actuation sleeves
• Return springs
• HNBR seal kits
• FKM seal kits
• High-temperature seal kits
• Backup rings
• Retaining rings
• Flow nozzles
• Internal bushings
• Thread protectors
• Complete overhaul kits

Frequently Asked Questions

What type of stabilizer is shown on this page?

This page covers the ZBW Hydraulic Variable Gauge Drilling Stabilizer.

It is not a conventional Integral Blade Stabilizer or Casing Centralizer.

What models are available?

The standard published models are:

• ZBW 8-1/2 in
• ZBW 8-3/4 in

How does the stabilizer extend?

Drilling-fluid differential pressure acts on the hydraulic mechanism and moves the support heads outward.

How does it retract?

When circulation stops and differential pressure falls, the return mechanism moves the support heads back toward the body.

What is the minimum extension pressure?

The standard listed minimum differential pressure for support-head extension is 0.1 MPa.

What is the maximum working pressure?

The maximum listed working pressure is 20 MPa.

What is the maximum allowable differential pressure?

The maximum listed allowable differential pressure is 40 MPa.

What radial support force does it produce?

The standard models provide 513 kN radial support force at a 10 MPa differential pressure.

How many support heads are installed?

Each standard ZBW model contains 15 support heads.

What is the internal bore?

The standard internal flow bore is 55 mm.

What connections are available?

The published configurations include:

• NC50 Box × NC50 Pin
• NC50 Box × NC46 Pin

Custom rotary-shouldered connections are available according to the BHA design.

Is the tool used for build-angle drilling?

Yes.

The tool can be installed in build-, hold- or drop-angle BHAs. The directional response is determined by the complete BHA configuration.

Does it enlarge the hole like an Underreamer?

No.

Its principal function is BHA stabilization and centralization. It does not replace a qualified cutting Underreamer.

Can it be used in horizontal wells?

Yes.

The retractable design is particularly useful where horizontal sections, doglegs and tight spots create high tripping resistance.

Can it be installed near the bit?

Yes.

Near-bit and String Stabilizer placement can be configured according to the approved BHA design and required connection arrangement.

Are tungsten-carbide support heads available?

Yes.

Support heads are supplied with carbide hardfacing, inserts, tiles or project-specific wear protection.

Are high-temperature seal kits available?

Yes.

HNBR, FKM and high-temperature elastomer packages are available for different mud and temperature conditions.

Is a non-magnetic version available?

A non-magnetic configuration is available for BHAs located near MWD, LWD and directional survey instruments.

How is the tool tested?

Testing includes material inspection, UT, MPI, connection gauging, hydraulic extension, automatic retraction, pressure holding, leakage and dimensional verification.

Information Required for Quotation

Please provide:

• Required nominal hole size
• Required expanded stabilizer OD
• Required retracted OD
• Bit diameter
• BHA position
• Near-bit or String Stabilizer application
• Top connection
• Bottom connection
• Required internal bore
• Maximum pump flow rate
• Minimum pump flow rate
• Normal standpipe pressure
• Available activation differential pressure
• Maximum allowable tool pressure loss
• Drilling-fluid type
• Mud density
• Solids content
• Chloride concentration
• Maximum circulating temperature
• Maximum static temperature
• Formation type
• Formation abrasiveness
• Expected rotary speed
• Expected weight on bit
• Maximum dogleg severity
• Build-, hold- or drop-angle requirement
• Carbide hardfacing type
• Non-magnetic material requirement
• Sour-service requirement
• Seal-material requirement
• Spare-parts package
• NDE requirements
• Third-party inspection
• Documentation requirements
• Required quantity
• Destination country
• Delivery schedule

Request a Technical Quotation

Goldenman supplies ZBW Hydraulic Variable Gauge Stabilizers for directional, horizontal and extended-reach drilling.

The standard range includes:

• ZBW 8-1/2 and ZBW 8-3/4 models
• 15-head hydraulic support systems
• Minimum activation pressure of 0.1 MPa
• 513 kN radial force at 10 MPa differential
• Maximum working pressure of 20 MPa
• Maximum allowable differential pressure of 40 MPa
• NC50 Box × NC46 Pin connections
• NC50 Box × NC50 Pin connections
• Alloy-steel and non-magnetic configurations
• Carbide hardfacing and replacement support heads
• High-temperature seal and overhaul kits

Complete tools are supplied with material traceability, connection inspection, UT and MPI reports, hydraulic function testing and pressure-test documentation.

Email: info@goldenman.com