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REDBACK Roller Reamers

Technical Overview

The Gearhart REDBACK Drilling Roller Reamer is a unique tool that is the result of a

research & development program launched by GEARHART UNITED PTY LTD,Australia to develop a roller reamer that is reliable and durable enough to be picked up

as part ofa drilling BHA.

The intention was to provide an effective solution to drilling-torque related challenges,

which are commonly created by stabilizers rotating in a poor hole-quality borehole or

when drilling long step out directional wells.

In the past the use of conventional roller reamers did not present a feasible solution

to these challenges as they lack both durability and reliability.

Todays field-proven advantages of using REDBACK roller reamers include, but arenot limited to the following:

1. Decrease of rotary torque and erratic torque values, thus allowing a more steady

drilling torque environment that results in positive drilling string/bits

performance, as follows.

Faster ROP.

Longer down-hole tools and bit life. Decreases/eliminates shock damage to drilling bits. With PDC type

benefiting the most.

Potential fewer trips per section.

Above would normally yield such savings that would greatly offset the

cost of using Redback roller reamers

2. Roller Reamers act like a bearing in between the BHA and the borehole, leading

to tangible reduction of drilling torque and hence, improve drill string

performance and minimise damage to tubular by reducing high stress loads.

Redback Drilling Tools, Newton Road, Kirkhill Ind. Estate,Dyce , Aberdeen, Scotland, AB21 0GE

Tel: +44 1224 774000, Fax +44 1224 774100, http://www.redbackdrillingtools.com

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3. Eliminates stabilizers hanging up in ledges or under-gauge intervals. This

commonly seen problem does result in severe drilling deficiency as well as

financial losses.

4. Minimises contact area with the well bores thus minimise the chance of

Differential- Sticking.

5. Wiped out doglegs greatly minimize the chances of Key-Seat stuck pipes.

6. Reaming while drilling eliminates a dedicated reaming/wiper trip.

7. Because of improved hole-quality casing and liners can be run faster and very

typically in one run.

9. Well suited to performance and steerable PDM applications.The

REDBACK Roller Reamers can provide the required stabilisation but with

the added benefits of reducing/steadying torque (slip-stick) and wiping out

micro dog legs without hanging up (reduced drag), improving the system

steering efficiency and bit performance.

10. REDBACK Roller Reamers enhance steer and slide better than stabilizers

when used behind motors due to the following design criteria.

The roller reamer body does not contact the well bores. Only 3-point contact

at the cutters offers less resistance to slide.

The cutters themselves are designed with a tapered (micro-step) profile to

balance the forces onto the cutting elements that also offer less resistance to

slide by having a lesser tendency to dig.

The cutters length is 3.1/2 in 12.1/4 tools and is only 3 in 8.1/2 tools,this small contact area is also conducive to less resistance to slide.

The following table summarises typical dimensional details of the most common

REDBACK Roller Reamer cutters:

Tool Nominal

Size

Roller reamer

Diameter

1st

Reduced Row

Diameter

2nd

Reduced Row

Diameter

3rd

Reduced Row

Diameter

6 6.000 -- -- --

8.1/2 8.500 8.400 8.300 --

12.1/4 12.250 12.150 12.050 11.950

17.1/2 17.500 17.400 17.300 17.200

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N.B. The full length of the cutting structure in a 12.1/4 tool (for example) is 10.20,

while the 8.1/2 cutter is 7.25 long. This excludes the two head blocks of the

cutter cartridge.

11. The patented Wedge Lock configuration cutter retention system, along

with the Sealed, Lubricated & Pressure Equalised Journal Bearing

design of our Redback roller reamers provide the following outstanding

performance:

Redbacks are the most reliable roller reamer in the market today, they have

been used in the harshest of drilling environments, performing well and

never loosing a cutter assembly in the hole, ever.

Highest bearing system durability due to the superior design. All most

common sizes of Redbacks have being used in excess of 3,000,000 cutters

revolutions and were pulled with effective bearings. The combination of an

effectively sealed, properly lubricated and pressure compensated bearing

system along with the proper selection of materials and optimised

dimensions make definitely our bearing system a superior design.

Redbacks patented and most efficient cutting structure configuration are

capable of tackling all kinds of reaming challenges and formations however

difficult. Roller reamers have the advantage of having to ream or destroy de-

stressed rock as opposed to bits that drill compressed rock and have been

used very successful in hard and well-cemented quartzite conglomerates,

hard and abrasive sandstones as well as plastic or swelling formations.

Metal Shims are available to help bringing worn cutters back in gauge,

thus further extending the life of the cutters.

Reamer bodies are made out of premium drill collar stocks, securing

excellent stress bearing characteristics under the most difficult dynamic

drilling conditions.