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BBL Dri llShoeTM
Information PackMay 2002 Version
CONTENTS
1. Overview of Drilling with Casing
2. What is a DrillShoe?
3. Facts and Figures about DrillShoes
4. Applications & Case Histories
5. Quality6. Cutting Structures
7. Hydraulics
8. DrillShoe Nose
9. DrillShoe Body
10. Running Procedures
11. Technology Developments
This Information Pack has been produced as an Introduction to BBL DrillShoes.The technology incorporated in these tools is new and is developing quickly.
If in any doubt, please contact the BBL staff listed below.
This version is accurate as of the date printed above.
Further revisions will be made as and when required.
BBL Downhole Tools Ltd Mike Wardley +44 1224
293656Suite 9, McNeil Business Centre [email protected]
Greenbank Cres., Jim Bain +1 713 973 9014
Aberdeen [email protected] 3BG Mitch Bavidge +44 1224 293663
Scotland [email protected]: +44 1224 293660
Fax: +44 1224 293669
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1. Overview of Drilling with Casing
Drilling with Casing is a new technology where the casing string is used as the drill stringinstead of drill pipe. To date, the technology has had limited exposure in worldwide oilfield
terms, with probably less than 200 applications. With the exception of a few experimental
wells, casing has been used to drill specific sections of the wellbore, rather than the entire
hole.
Drilling with Casing comes in two flavours. In one arrangement, a hydraulic motor islatched into the lowermost casing joint along with a packer. The casing is advanced by
pumping through the motor, in much the same way as slide drilling is accomplished
conventionally on drill pipe. When TD is reached, a retrieval tool is run, which has to be
latched into the BHA. Overpull is applied to recover the BHA.
BBL have adopted a different approach. With the BBL system, the casing is simplyrotated, in exactly the same way as drill pipe. A crossover to the top drive is used to
transmit torque. The unique feature of the BBL system is that the drill bit (DrillShoe)is fully drillable this means that once the section is completed, there is no drill bit to
recover through the casing. Cementing can begin immediately and then the next bit is run
and drills-out the shoe track in exactly the same way as a conventional operation.
The BBL system is currently targeted at soft to medium-soft, straight hole sections which
are capable of being drilled with a single bit run. Ongoing and future developments arediscussed in section 11.
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9-5/8 x 12-1/4 DrillShoe with
Tungsten Carbide HVOF
Cutting Structure
2. What is a DrillShoe?
A DrillShoe is BBLs term for a Drillable Casing Drill Bit. The
DrillShoe is made up to the casing in the same way as a conventional drill
bit would be made up to a drill string.
The DrillShoe has a two part construction;
A body, which has the casing connection and a gauge sectionmade from steel, &
A nose, which is made from aluminium alloy, upon which is
mounted a drillable cutting structure.
The two parts are threaded and locked together and the tool is supplied
as a unit, as shown.
In the applications to date, two cutting structures, composed of denseTungsten Carbide or Thermally Stable Diamond have been used.
The nose of the DrillShoe has flow ports or nozzles strategically
positioned to clean and cool the cutting structure and flush away thecuttings up the annulus.
The entire unit is fully drillable with PDC or roller cone drill bits.
When the casing is rotated, the cutting structure cuts the rock with a
shearing action, in the same way as PDC cutters on a
conventional drill bit.
When TD is reached cementing can begin immediately a
non-return valve may be incorporated in the DrillShoe and / or
float collars in the casing string.
After waiting-on-cement the next drill bit is run and drills
through the shoetrack and DrillShoe before entering virgin
formation.
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3. Facts and Figures about BBL DrillShoes
Invented in Nov 1999 for drilling in surface casing in the Gulf of Thailand
Designed in collaboration with Unocal Thailand
First tool run in Jan 2000
Became the Standard Technique in the Gulf of Thailand by Apr 2000
Patents applied for in 1998/99/2000
Smallest Tool (to date) 5 x 6-3/4
Largest Tool (to date) 20 x 24
48 tools run to Nov 2000 with eight customers with a 100% success rate
A total of 68 tools delivered (to Nov 2000)
The Original 1999 Design
This design (7-5/8 x 9-7/8) had HVOF cutting
structure on high blades and a Cutrite
reaming action.
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4. Applications & Case Histories
Applications to date have been extended to drilling-in surface casing from jack-ups and
platforms, second strings after setting conductor pipe or drilling with liners. In the Gulf of
Thailand, the Standard Procedure for drilling and setting surface casing is to use a DrillShoe.
- Gulf of Thailand - Jan 2000 Case History No.1
Well No. Yala 6
Casing String 9-5/8 Surface Casing
Connection Buttress
Distance Drilled 690 ft
On-Bottom Time 2.3 hrs
Average ROP 300 ft/hr
Running Parameters
WOB 0-10 klbs
RPM 60-150
Torque 2 - 7 kftlb
Flow 790 gpm
Comments
Coal stringers caused torque spikes and reduced overall ROP.
Drilled-out with BB452 in 15 mins Pulled-back and Reamed DrillShoe Bit Damaged
- Gulf of Thailand - Feb 2000 Case History No.2
Well No. Arthit 15-3X
Casing String 9-5/8 Surface Casing
Connection Buttress
Distance Drilled 780 ft
Total / On-Bottom Time 6.0 / 1.3 hrs
Average ROP 607 ft/hr
Running Parameters
WOB 2-12 klbs
RPM 50 90
Torque 1 - 2 kftlb
Flow 870 gpm
Comments
Very fast run.
Drilled-out with BB452 in 10 mins - No Damage to Bit.
- Chevron Thailand - May 2000 Case History No.3
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Well No. Kung 2
Casing String 9-5/8 Surface Casing
Connection Buttress
Distance Drilled 693 ft
IADC Time 2.9 hrs
IADC ROP 239 ft/hr
Running Parameters
WOB 2-10 klbs
RPM 50 90
Torque 1 2.5 kftlb
Flow 870 gpm
Comments
Overall ROP reduced, slow progress through rotary with straked casing.
Drilled-out with PDC bit - No Damage to Bit.
- Vietnam - Jun 2000 Case History No.4
Well No. 48/95-TDD-1X
Casing String 9-5/8 Surface Casing
Connection Buttress
Distance Drilled 732 ft
Total / On-Bottom Time ? / 2.5 hrs
Average ROP 287 ft/hr
Running Parameters
WOB 4-16 klbs
RPM 110
Torque 0.5 2.0 kftlb
Flow 850 gpm
Comments
First 550 ft, drilled at 460 ft/hr
Slowed down over last 180ft Firmer Formation
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- Unocal Indonesia - Jul 2000 Case History No.5
Well No. YN-23HZ
Casing String 13-3/8 Surface Casing
Connection Buttress
Distance Drilled 493 ft
On-Bottom Time 1.3 hrs
Average ROP 372 ft/hr
Running Parameters
WOB 24-13 klbs
RPM 40 100
Torque 1 3.5 kftlb
Flow 400-800 gpm
Comments
Drilled thru three sand stringers at about 30 ft/hr
Drilled-out with PDC bit - No Damage to Bit.
- Chevron USA - Nov 2000 Case History No.6
Well No. Viosca Knoll 70 #1 WB1
Casing String 13-3/8 Second String
Connection Buttress
Distance Drilled 729 ftROP Variable (>400 ft/hr in sand / < 50 ft/hr in Gumbo)
Running Parameters
WOB 2 - 15klbs
RPM 50 - 60
Torque 2 3 kftlb
Flow 930 gpm
Comments
Drilled out with Roller Cone Bit
Design has been improved to cope with Gumbo
First Run with
Diamond (TSP)
Cutting Structure
First Gulf of Mexico Run
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- Phillips Australia - Nov 2000 Case History No.7
Well No. Coleraine ZOCA 96-16
Casing String 7 Liner
Connection New Vam
Distance Drilled 179 m
Running Parameters
Torque
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5. Quality and BBL
BBL has ISO9001 accreditation covering Design and Manufacture of Drill Bits and
Downhole Tools. BBL gained accreditation in 1993. BBL is accredited by Det Norske
Veritas (DNV). DNV is one of the worlds leading quality assurance organisations.
All BBL DrillShoes are manufactured to set procedures and a Certificate of Conformance is
issued with all tools.
Where the thread is cut before despatch from BBL, we will include a copy of the third party
licensees thread certificate.
All tools are drifted to API 5CT Specifications or to special drift requirements if specified in
the order.
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6. Cutting Structures
Two cutting structures are available and field proven; tungsten carbide and thermally stable
diamond. Both cutting structures have been designed to be fully drillable with any type of
oilfield drill bit, without damage to the drill bit cutters.
1st
Generation tools utilise a hard and dense layer of tungsten carbide (TC) as the cutting
structure. The layer can be between 0.006 and 0.120 thick depending on application. TheTC is applied using a proprietary process known as High-Velocity-Oxy-Fuel (HVOF), the
photograph below shows the TC being applied to a 1 subsea gate valve. HVOF tools are
designed for the very softest of oilfield formations.
The HVOF process involves firing minute particles of TC at the workpiece at supersonic
speeds. Upon impact the particles weld themselves to the workpiece. The result is a hard,
non-porous coating which has a very high bond strength to the underlying material.
BBLs 2nd
Generation tools utilise thermally stable diamond (TSP) where the formations are
too firm for HVOF. TSP has about 10x the hardness of TC and is able to drill formations
effectively where TC would wear out. Pre-formed monolithic pieces of TSP are attached to
the aluminium nose by a proprietary process.
Applications of these cutting structures to drillable tools have been patented by BBL.
7. Hydraulics
Originally, all DrillShoes were run with open ports. This was because interchangeable drill bit
nozzles are constructed from tungsten carbide and are simply not drillable. Typically the TFA
with open ports has been about 5 sqin, to avoid eroding the soft aluminium nose of theDrillShoe. The DrillShoe pressure drop is about 40 psi and the HSI is
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8. DrillShoe Nose
The leading end of the DrillShoe is termed the Nose. The nose of the shoe is fully drillable
with any standard oilfield bit.
An Aluminium material has been specifically chosen to allow the bit to drill through the noseeasily. In addition, BBL DrillShoes incorporate chipbreakers into the tool nose to ensure that
the aluminium cuttings do not birds-nest the drill bit.
Chipbreaker Holes Small Chips during Drill-Out
(Note: The material and internal design of the Nose are identical to the Award Winning BBL
Reamer Shoe. Over 1250 of these tools have been run worldwide with not a single instanceof bit damage when drilling-out).
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9. DrillShoe Body
All DrillShoes are box-up. The tool has a single-piece integral box connection, BBL does
not use a coupling, and the casing pin can be stabbed straight into the tool.
DrillShoe bodies are made from AISI 4145 steel, unless otherwise specified. This is thesame grade of steel as used for the manufacture of drill collars.
In terms of casing grades, 4145 is superior to P110. So for a casing string of P110 or
lesser grade, the tool is inherently stronger than the casing. Even if the casing grade is
higher, say Q125, the DrillShoe is never the weak link in the chain, since wall sections are
always thicker than the corresponding casing. If required, BBL can supply minimum burst andcollapse pressures for DrillShoes.
Stabiliser blades are a feature of all DrillShoes. BBL DrillShoes incorporate ground
Tungsten Carbide stabiliser blades as standard. The blades stabilise the DrillShoe in thesame way as the Gauge Pads on a Drill Bit.
At the uphole end of the stabiliser blades, a backreaming facility is included as standard.
These Cutrite carbide blades ensure that the tool can be used to back-ream if necessary.
This feature is particularly useful in swelling shale formations, where the formation may be
continuously moving.
The hard faced stabiliser blades provide good stand off at the shoe for an improved cementjob.
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10. Running Procedures (typical)
General Information and Recommendations
The tool is set with high density, HVOF tungsten carbide or Thermally Stable Diamond (TSP)
cutting structure on the front and tops of the blades. The nose of the tool is constructed from
aluminium alloy, which is fully drillable with any type of oilfield drill bit. This tool is very aggressiveand will drill very quickly with low WOB. Aggressive Drilling Tools can generate high torque for
low weight. It is recommended that WOB be kept to a minimum until the torque response
of the DrillShoe is known. This may take a few joints. Applying high weight, too early, may
over-torque the casing connections.
On no account sho u ld the too l be set on bot tom unless
ful l pum p rate and rotat ion have been achieved.
Preparation Prior to RunningUnpack the tool and make the following checks:
Check and record the serial number, tool size and type Confirm no damage to aluminium nose or cutting structure Check that the ports are clear Remove thread protector and check for damage Confirm that there is no debris inside the tool
Making-Up to the Casing Drilling String
Stand the DrillShoe box-up on a rubber mat or wooden board Stab in the casing joint and make-up to normal torque
Pick-up and run casing as per normal procedure until one joint fromtagging bottom.
Make-up casing joint with water bushing
Initiating the Drilling Process
Pump at high flow rate rotate as per the product recommendations Zero the weight indicator, record pump pressure and rotary torque Run down slowly to the mudline, carefully monitoring WOB, torque and pressure
It is recommended that the first joint is drilled down with minimum weight to
establish the hole and give lateral stability to the casing string.
Drilling Ahead Always kick in the pumps and rotate before going to bottom
Increase weight gradually to achieve desired ROP Remember that excessive WOB will reduce tool life
Monitor pump pressure carefully, an increase may indicate bit balling. Pick up off bottom,
rotate at max rpm, and stop and start the pumps several times to try to wash the DrillShoe
clean of cuttings
Drilling Out with a Bit
The aluminium nose is best drilled with med WOB, low RPM and maximum flow rate (if
run on a PDM, reduce flow rate to give a maximum of 150rpm total) Expect to take 5 20 minutes to drill through the nose
Once into the rathole proceed as per the drill bit manufacturers recommendations Do NOT rotate when pulling BHA up thru the shoe unless absolutely necessary
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Drilling Out with a DrillShoe The aluminium nose is best drilled with very low WOB, low RPM and max. flow rate.
Expect to take 10 30 minutes to drill through the nose Once into the rathole proceed as per the product recommendations above Do NOT rotate when pulling BHA up thru the shoe unless absolutely necessary
11. Summary of Ongoing & Future Developments
Displaceable / Retractable Cutting Structures
It is expected that formations harder than medium-soft may require an even more competent
cutting structure than Drillable Diamond. For these applications BBL are developing a
DrillShoe with a PDC cutting structure that is displaced into the annulus after reaching TD.
The next drill bit simply has to drill through an aluminium nose of the DrillShoe and does notencounter any hard obstructions.
Steerability
BBL is looking beyond applications to straight hole drilling and are developing steerable
versions of the DrillShoe. These tools will be run on an orientable BHA suspended below the
casing shoe. Steering is done by orienting the casing and pumping through the motor. To drill
straight ahead, both the casing and the motor are rotated.
At TD the BHA is pulled back to surface, leaving the DrillShoe latched to the casing shoe.
Since the DrillShoe incorporates a non-return valve, cementing can proceed immediately.
Retrievable/Replaceable DrillShoe
The current ranges of DrillShoes are required to drill the entire section to TD. A failure to
succeed may involve pulling the casing string. BBL is actively engaged in a development
process to enable recovery and replaceability of the DrillShoe. This range of tools will allow
the possibility of casing-drilling multi-bit wellbore sections, combined with the advantage of
DrillShoe drilllability.