Remote Removal of Damaged

Steel Liner From Vent Shaft

Angus Place East Mine Expansion

Vent Shaft 1

Australian Shaft Drilling

ASD was formed in 2003 and proceeded to design and build a blind bore drill rig to service the Bowen Basin mines.

The company won its first contract for Moranbah North to drill a 2.2m finished diameter shaft to a depth of 275m.

The Shaft was completed in June 2005 and was quickly followed by a 4.5m diameter shaft drilled to 230m for the same mine.

Since that time ASD have expanded operations, built three new drill rigs and have at times managed four drilling projects concurrently. Some of the projects include

Kestrel Coal Drill 3.8m diameter to 230m depth lined with steel

Carborough Downs Drilled 5.4m to 150m

Kestrel Mine Extension Drill 5.5m diameter to 230m

Narrabri No 1 Vent Shaft Drill 5.5m diameter to 200m deep

Lady Loretta Vent Shaft Drilled at 5.4m diameter to 148m

Moranbah North Vent shafts two shafts drilled at 2.6m diameter to depths up to 345m

Grosvenor Mine Shafts 3 vent shafts, two at 2.6m Diameter and one at 6m Diameter to 170m

Angus Place East Mine Extension Site ASD was contracted to Centennial Coals Angus Place Colliery for the installation of the new Ventilation Shafts for Angus Place East which is a proposed extension of the Angus Place mine workings

The Drill site is located on the Newnes Plateau approximately 15 minutes from Lithgow

Vent Shaft Details Vent Shaft 1

Total Lined Depth 393m

Finished Lined Diameter 3.5m

Initial Drill Depth 75m @ 5m Dia

Lined with Dia 4.6 Steel casing

Final Drill Depth 396m @ 4.5 Dia

Lined with Dia 3.5 Steel casing

Liner Breakdown Lower Section 108m is made up of 9 x 12m sections of 20mm G350 Plate 230PFC stiffening rings at 1m spacing's Middle Section 108m is made up of 9 x 12m sections of 16mm G350 Plate 230PFC stiffening rings at 1.2m spacing's Upper Section 177m is made up of 15 x 12m sections of 12mm G350 Plate 230PFC stiffening rings at 1.5m spacing's

Floating of Liners Floating of Liners is undertaken when the weight of the liner is too large to handle with the Drill Rig and shaft is straight

The Rig being used in this instance was the SDR6500 this rig has a WWL of 300t. The Total liner weight to be installed was 615t

The process is to seal the bottom liner with a water tight bulkhead. This turns the liner tube into a sealed unit which floats. As each section is welded on to the top, fluid is pumped into the liner to equalize the buoyancy to allow controlled sinking of the liner sections. There is always a slight negative buoyancy

Bottom Liner Segment 20mm Plate Bulk Head Multiple Reinforcement Rings UB Beams Reinforcement

Valves to allow drainage when holing in from Mine

Loss of Liner (November 2014)

When Floating down section 29of Liner we had an unexpectedchange in buoyancy whichcaused the liner to sink

The lifting equipment broke away from the liner as designedto do to save the rig fromdamage

The liner sank to the bottom of the shaft approximately 45mbelow the collar

Initial investigations pointed to afailure in the liner wall which allowed an uncontrolled influx of water into the liner

There is some conjecture overwhat caused the split

External damaged during sinking Design fault due to the liner being

out of round reducing the F.O.S

Australian Standards for amount of deformation of Pressure Vessels

1% difference between Min and Max Dia

Deviation of 0.3% over Chord Length of .25 D

Chord Length 875mm Deviation 10.5mm

Deformation in Liner In Manufacture

Diameter 3.5 Liner Weights Installed

Liner Sections Number Off Weight (t) Length (m) Total lenghts (m) Quanity Length (m) Mass (t) 1 x 9m @ 12mm 1 12 9 0 0 14 x 12m @ 12mm 14 14.7 12 168 11 132 161.7 9 x 12m @ 16mm 9 19.6 12 108 9 108 176.4 8 x 12m @ 20mm 8 24 12 96 8 96 192 1 x 12m @ 20mm + Bulkhead 1 31 12 12 1 12 31

Diameter 3.5m 9.62 m2 393 29 348 561.1 t

Pressure Force 572.11 Kpa

Differential Fluid Height 53.0 m (SG 1.1)

Liner Sank 45m Water level inside Liner approximately 50m Below Collar Water level outside liner is level with collar

Sheet1

Diameter 3.5 Liner

Weights Installed

Liner SectionsNumber OffWeight (t)Length (m)Total lenghts (m)QuanityLength (m) Mass (t)

1 x 9m @ 12mm112900

14 x 12m @ 12mm1414.71216811132161.7

9 x 12m @ 16mm919.6121089108176.4

8 x 12m @ 20mm8241296896192

1 x 12m @ 20mm + Bulkhead131121211231

Diameter 3.5m9.62m239329348561.1t

Pressure Force572.11Kpa

Differential Fluid Height53.0m

(SG 1.1)

Damage Investigation

Fluid was pumped out of the shaft to reveal what the damage to the steel liner was

First Picture is with water pumped to 87m below the collar

The Liner above this is still

reasonable circular

Damage at section 87 to 93m

Liner stays a kidney shape down to141m and below During the pumping of fluid out for the initial investigations the liner toreopen at 141m due to pressuredifference and the liners weakened state Another small split developed in thewall at 155m There is no video of the liner shapeafter this depth. Due to having topump internally and externally tokeep the fluid levels balanced so notto propagate any more damage

So only split in liner before pumpingwas at 93m Liner below that was intact but deformed in the classic 2 lobe failure mode of thin walled cylinders

Sonic Calipier As the damage to the liner in the upper sections was too great to use our usual measuring instruments. We researched what instruments would be able to internally measure the diameter of a steel liner immersed in fluid.

The Sonic Caliper is a profiling sonar device specially adapted to function in drilling fluid.

Each 360 degree pass with the Sonic Calipier generates up to 120 individual echo returns. A geometric shape is fitted to the data points using the non-linear least squares technique. The plots indicated that below 180m the liner was round and not damaged. This depth coincided with the change in liner wall from 12mm to 16mm plate.

180 to 210m 290 to 317m

Decision to Proceed with Removal of Damaged Liner ASD developed a methodology for the reclaim of the liner which was

submitted to Centennial Coal for consideration and risk analysis; the methodology involved the cutting of the liner using a High Pressure Water Jet Cutter, then lifting of the cut sections to the shaft collar, followed by the removal of the damaged sections.

Following the Risk Assessment process the methodology was additionally peer reviewed by an independent engineering party with the consensus being that the reclaim was achievable. Australian Shaft Drilling commenced the reclaim work in early 2016 and is ongoing.

Basic Methodology for Liner Removal

The first section of liner to be removed started at 45m below shaft collar

Method was to cut two windows at top of liner section to be removed Cut the separation cut. This could be 12m or longer sections Install the lifting grapples or Lifting Beam Raise to the surface Lift out of shaft and remove from work area

Water Jet Cutter Two types of water jet cutters Garnet added at Nozzle (venturi mix) Garnet added upstream (slurry mix) Chose second type Due to no access to the

hopper. Pressure at nozzles is 1500 Bar Nozzles 0.8mm Garnet 80mesh - 177 microns 13L per minute water usage 60kg of garnet per hour (50% mix)

Cutting Tool No 1

This Cutting tool had telescopic arms in both directions

Idea behind design was front arm carried the high pressure cutting nozzles and the back arm was used to push against the opposite wall to keep the head steady during the cutting process.

Cameras where positioned at several different points to obtain views of the cutting nozzles and other areas.

Two cutting nozzles where fitted for redundancy

Rotation and Vertical Lift while Cutting

Good Cutting

Cutting at

Distance

Camera Vision

Damage to Camera lens

Cutting Tags due to poor visibility

Window Cutting

Grapple Installed in Window ready for lifting of Section

Crane Lift Grapple

Separation Cut

Chairing of Liner Section on Collar Welding of Lift Lugs

Removal of Liner Section from Shaft

First Three Sections Removed

Tear at 93m

Robot Cutting Arm

Robot Cutting Arm Nozzle Tip

Lowering Cutting Arm through Highly Damaged area to cut depth at 93m

Highly Damaged section area removed

Top of Liner at 93m

Pressing of Liner to reshape to allow better access for cutting and lifting. First 6m below the 93m edge

Liner Reformed at top section to allow lifting beam insertion

Windows Cut at 97m

Tear at 141 m

Liner Shape at 141m

Cutting of Separation at 141m

Pushing of Separation cut to check actual separation of Liner

Lift Beam inserted into windows ready for lifting of liner section

Top Risk from RA

Monitor Shaft Wall for collapse

Shaft Wall Erosion

Remote Removal of Damaged Steel Liner From Vent ShaftAustralian Shaft DrillingSlide Number 3Angus Place East Mine Extension SiteVent Shaft DetailsSlide Number 6Slide Number 7Floating of LinersSlide Number 9Slide Number 10Slide Number 11Slide Number 12Loss of Liner (November 2014) Slide Number 14Slide Number 15Slide Number 16Damage InvestigationDamage at section 87 to 93mSlide Number 19Sonic Calipier Slide Number 21Decision to Proceed with Removal of Damaged LinerBasic Methodology for Liner RemovalWater Jet CutterCutting Tool No 1Rotation and Vertical Lift while CuttingSlide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Highly Damaged section area removedTop of Liner at 93m Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Lift Beam inserted into windows ready for lifting of liner sectionSlide Number 52Slide Number 53Slide Number 54