Spe 74514

Copyright 2002, Society of Petroleum Engineers Inc.

This paper was prepared for presentation at the IADC/SPE Drilling Conference held in Dallas,Texas, 2628 February 2002.

This paper was selected for presentation by an SPE Program Committee following review ofinformation contained in an abstract submitted by the author(s). Contents of the paper, aspresented, have not been reviewed by the Society of Petroleum Engineers and are subject tocorrection by the author(s). The material, as presented, does not necessarily reflect anyposition of the Society of Petroleum Engineers, its officers, or members. Papers presented atSPE meetings are subject to publication review by Editorial Committees of the Society ofPetroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paperfor commercial purposes without the written consent of the Society of Petroleum Engineers isprohibited. Permission to reproduce in print is restricted to an abstract of not more than 300words; illustrations may not be copied. The abstract must contain conspicuousacknowledgment of where and by whom the paper was presented. Write Librarian, SPE, P.O.Box 833836, Richardson, TX 75083-3836, U.S.A., fax 01-972-952-9435.

AbstractThis paper describes the successful development andapplication of a new low-friction flouropolymer-based coatingapplied to PDC bits to minimize and often prevent ballingwhile drilling shale formations. Successful laboratory testing,the results of several field runs and one field case study will bepresented. The rate of penetration is shown to more thandouble in certain cases resulting in significant savings to theoperator.

IntroductionDuring development of the new coating process, full-sizedcommercial bits were tested in a laboratory under verycontrolled, simulated downhole conditions with and withoutthe proprietary coating. The authors will present data fromthese laboratory tests, summarize several successful field runsand provide detailed results of one case study where a coatedbit was used in the Tembungo B9 well for Petronas Carigali inMalaysia. This flouropolymer-based coating more thandoubled the average penetration rate relative to standard PDCbits traditionally used to drill this hole section.

The Malaysian case study will document that the coatingprevented bit balling while drilling more than 1,400 feet.Although the coating was eroded at the conclusion of the run,the test was considered successful because of the significantimprovement in average rate of penetration. Additionally, theauthors document the economic savings of preventingdownhole balling with PDC bits in water-based muds.

BackgroundPDC bits drilling with oil-based muds (OBM) or synthetic-based muds (SBM) have consistently set the performancebenchmark for drilling shales, especially in deep, highpressured wells. The exceptions are areas where tighteningenvironmental regulations, high risk of lost circulation and/ormarginal project economics make use of OBM/SBMunattractive. These areas are growing and this has persuadedoperators and service companies to invest considerableresources into trying to improve the performance of PDC bitswith water-based muds.(1)

The worldwide average penetration rate in deep,overpressured sections experienced by one major operator in1997 was 12.7 feet per hour. Taking the figures for water-based mud alone, the average penetration rate was even lower.

The combination of oil-based muds and PDC bits gave thebest overall average rate of 17.3 feet per hour. It wasrecognized that if this performance could be achieved in allwells, the annual worldwide savings would exceed $500million.(4) However, the use of oil-based muds is prohibited orrestricted by environmental, safety, and other considerations inmany parts of the world. Therefore, innovative methods mustbe found to solve the bit-balling problem, and increase drillingpenetration rates with water-based muds.

Causes and Prevention of Bit BallingWhen drilled with a PDC bit, rock tends to fail in shear,scraping cuttings off of the bottom of the borehole. PDC bitballing occurs when the chips do not separate themselves fromthe cutters and, instead, accumulate on the body of the bit.(5)(6)

Historically there has been confusion about what causesdrilling cuttings to agglomerate and attach themselves to thebit and bottom hole assembly.

When shale material fails due to the cutting action, there is asudden and large increase in formation porosity and acorresponding drop in pore pressure.(3) This phenomenon isknown as rock dilation. In addition, most clay-rich shalesexhibit a pronounced tendency to hydrate i.e. draw water into

SPE 74514

Innovative Low-Friction Coating Reduces PDC Balling and Doubles ROP DrillingShales with WBMM. Rujhan Mat and Mohd Zulkifi Bin Zakaria, Petronas Carigali, Steve Radford and Darren Eckstrom, HughesChristensen/Baker Hughes

2 ZAKARIA, MAT, RADFORD, ECKSTROM SPE 74514

the clay fabric and swell upon rock failure. Thus, right afterfailure we are left with a shale chip that combines low porepressure (due to rock dilation) with a pronounced tendency tohydrate (due to the effects of the swelling pressure). Whensuch a cutting comes in contact with the bit-face, it becomesisolated from the mud pressure on that side, and may be heldin place by differential pressure. The material, thus,vacuums itself onto the bit face or, if present, onto othercuttings.(1)

Field experience shows that bit-balling problems are oftenmore severe deeper in the well, i.e. at high hydrostaticpressure.(2) One report concluded that the bit performance inonly the deep, over-pressured sections of wells representedalmost 20 percent of the total cost of such wells or about $2.9billion worldwide in 1997. (4)

To be successful in preventing bit balling, the problem mustbe approached in a systematic manner, addressing manyelements: including bit design, drilling mud design, hydraulicsand the surface characteristics of the bit.

It has been recognized for some time that certain bit featurestend to minimize bit balling. The most common of these arelarge open face volume and junk slot area combined withoptimized nozzle placement and adequate hydraulichorsepower. These variables are most effectively optimizedusing numerical modelling through computational fluiddynamics (CFD) computer software. Other importantconsiderations include focus on chip management with sharp,polished cutters(3), aggressive rake angles and edge geometry.

Depth of cut control through operating parameters and bitdesign features is another way to limit cuttings volume andsize.(1)

Bland, et al, concluded that, with some limitations, use ofsynthetic-based mud or the addition of Drilling Enhancers towater-based mud were effective in increasing rate ofpenetration and preventing balling of PDC bits. The drillingenhancer appears, in some cases, to keep the cuttings morediscrete, helping to reduce their creation of cohesive masses.

Bit Anti-Balling TreatmentsVarious types of anti-balling coating systems have beenapplied to PDC bits for over 20 years, but with very limitedsuccess. They have ranged from ultra-smooth epoxy paints tonickel plating, rare metals, and nitriding.

There is also published university laboratory research showingthat the application of strong electrical potential reduces theelectrical attraction of shale to steel. Claims have been madeby one bit manufacturer that the very small latent negativecharge left after applying a proprietary processing technique tothe surface of a steel-body PDC bit is sufficient to accomplishthis phenomenon. No known research has been published of afull-scale bit being tested under controlled conditions with and

without the treatment. Some results are presented later in thispaper, which provide an indication of the relative effectivenessof this treatment.

Coating Development For many years, PDC bit manufacturers have recognized thegreat potential of an effective non-stick coating that couldprevent bit balling.

Teflon, which was accidentally invented by engineers atduPont in 1938, is the best known of the non-stick coatings,and novel uses for its unique properties continue to bediscovered. Flouropolymers like Teflon have the uniqueproperty of being non-water-wet with very excellent releaseproperties. In other words, clay and shale will not adhere toflouropolymer coatings.

At various times over at least the past 20 years, Hughes ToolCo. and Christensen Diamond Products have tested Tefloncoatings. Along with the many attempts that were made byother bit manufacturers, the results were disappointing.Success has fiinally been achieved however, with thedevelopment of a coating process that uses a speciallyformulated, reinforced Teflon-like flouropolymer.

When used alone, Teflon and other flouropolymer coatingsare relatively soft and only attach to a surface mechanically,not chemically. This effectively means that the roughness ofthe surface is the only thing holding the coating in place.Typically, the coating was found to peel, scrape or erode veryquickly. After nearly three years of experimentation,however, a new reinforced flouropolymer coating process hasbeen developed, which has proven very successful.

The new coating, which was developed cooperatively by a bitmanufacturer and a commercial coating supplier, retains all ofthe non-stick properties of Teflon, along with greatlyimproved durability and enhanced ability to adhere to a basesurface. The coating is reinforced with proprietary additivesto give it extraordinary toughness. To improve adhesion, thesurface of the matrix or steel body bit undergoes a specialroughening process that gives the coating a three-dimensionalprofile to grip. When this is used together with a newlydeveloped surface primer to chemically assist in the adhesion,the coating develops an excellent bond to the bit.

Laboratory TestingSingle Point Cutter TestingInitial testing was performed in the Hughes Christensenlaboratory, utilizing a traditional Single Point Cutter machine.The models used to test the coatings had no PDC cutter, butwere simply machined from steel. Tests were performed inthe apparatus cutting Catoosa shale (a typically balling shale)in water both before coating and then after coating. Twosamples were coated with different types of commercialTeflon and two others were plated with a commercial nickel-Teflon plating process.

SPE 74514 INNOVATIVE LOW-FRICTION COATING REDUCES PDC BALLING AND DOUBLES ROP DRILLING SHALES WITH WBM 3

Figure 1 shows that one of the Teflon formulations reducedaxial force by 25% and tangential force and coefficient offriction by lesser amounts. These results gave initialindication that flouropolymer coating could increase bit ROP.It was also noted that the commercial nickel/Teflon platingswould probably not be effective.

Baseline Full-scale Bit TestingA 6 inch IADC M332 bit was selected as the baseline testbit and run in a downhole drilling simulator located at theHughes Christensen research facility.

The bit was intentionally run at conditions that would promoteshale bit balling, drilling Catoosa shale with 1.0 hsi, 250 gpm,240 rpm, with 9.5 ppg water-based FW/CLS mud at 6000 psiconfining pressure.

Figure 2 shows results of testing this baseline, uncoated bit,compared to the same bit coated with ceramic/epoxy (CK); aplastic/Teflon composition; nickel-Teflon plating; andanother commercial downhole flouropolymer coating(Comm01). These are compared against developmental bitcoatings 9901B, 9901E, and 9901F.

It can be seen from the results that the Comm01 coating wasthe only coating with performance close to the developmental9901 coatings, but still had 40% lower ROP. Thedevelopmental 9901 series of coatings all provided ROP ofover four times that of the bare matrix baseline bit. Allcoatings exhibited full or partial shale balling at the conclusionof the tests. The baseline uncoated bit was fully balled upwith shale at 3,500 lb WOB.

Simulator Testing of Two Commercial BitsTwo full-sized commercial PDC drill bits were tested bothuncoated and then coated in a downhole drilling simulator attypical downhole drilling conditions. Both showed substantialROP improvement with the 9901 coating. Neither coated bitexperienced bit balling and both pushed the simulator to itsmaximum ROP.

Figure 3 shows the results of running an 8 IADC M323PDC bit, a commercial bit typically run in soft shaleformations, in a downhole simulator. The bit drilled Catoosashale in 9.5 ppg WBM at typical conditions. The uncoatedmatrix bit drilled with a maximum ROP of 200 fph beforeballing, while the coated bit did not experience bit balling andwas able to attain a test-machine maximum ROP of 270 fph.

The coated bit drilled 25-50 fph faster at all bit weights. Thecoating, therefore, not only prevented bit balling, but it seemsto have improved penetration rate throughout the test.

Historically few bits have drilled to maximum simulatorpenetration rate in high weight (16 ppg) water-based mud,when drilling Catoosa shale. The uncoated developmental 8

IADC M223 bit balled in the shale at a normallyrespectable 175 fph (see Figure 4). However, coating the bitwith the test coating prevented balling and allowed thesimulator to drill to its maximum ROP of 270 fph beforeceasing the test. Figure 5 shows a typical full-sized bit coatedwith the proprietary reinforced flouropolymer coating.

Case Study: MalaysiaPetronas Carigali has historically experienced bit ballingproblems offshore Malaysia, in some formations below 8,000-foot depth when using water-based mud. Having achievedsome improvement in a previous well using a commercial bitwhich was treated with a process involving surface electricalcharge, Petronas Carigali decided to try a Hughes Christensenbit with reinforced flouropolymer coating on the TembungoB9 well. The uncoated PDC IADC M323 bit is shown asFigure 6.

Field HistoryA six-slot jacket was installed in the Tembungo field inSeptember 1993. This field is about 48 miles northwest of thecity of Kota Kinabulu, which is on the island of Sabah(Borneo) in Malaysia (see map Figure 7). The initial projectwas completed in February 1995 after a seventh slot wasinstalled. Two more slots were installed in January 2000,during the Tembungo Western Area Further FieldDevelopment project, and wells were drilled to nearly 13,000-foot depth.

Tembungo B9 was spudded in March 2000. The reinforcedflouropolymer coated PDC bit was run in the 12 holesection, and reached a section TD of 11,527 feet. TembungoB9 was the final well of the project, and was completed as adual string selective oil producer in April 2000.

Case Study DetailsAs typical of the previous eight wells drilled with water-basedmud in the Tembungo Western Area, the ROP on TembungoB9 sharply decreased due to bit balling as the well reachedgreater depths with higher mud weights being used. Figures 8and 9 show that at hole depth shallower than 7,800-ft, the rateof penetration remained a reasonable 67 fph with a light-setPDC bit. Thereafter as the well depth increased, the ROPdecreased even though PDC and aggressive milled-tooth rollercone bits were used.

A PDC bit run achieved 43 fph, following which, successiveruns with roller cone and PDC bits never exceeding 30 fph,one PDC bit drilling at only 10 fph. At that point, PetronasCarigali decided to try a PDC bit that was coated with thenewly developed reinforced flouropolymer coating. Thepotential risks associated with running the coated bit wereconsidered minimal since the IADC M323 bit style (HCCBD535), had been the top ROP performer in the 8 holesection of the previous Tembungo B8 well, and it wasconsidered unlikely that the bit coating could adversely affectperformance.


Case Study ResultsThe PDC bit was run at a depth of 10,125 ft. with the drillingconditions and parameters described in Figure 8. The bitdrilled 483 feet at 101 fph until an MWD failure required thedrill string to be tripped out of the hole. This, however,allowed inspection of the bit, which was still found to be inexcellent condition and was rerun. The 12 hole sectionreached TD with this bit at 11,527 ft with an overall bit ROPof 72.3 fph. As can be seen in Figure 9, this overall averageROP of the polymer-coated bit was DOUBLE the average ofall other bits previously run in the 12 hole section with a95% ROP increase. Compared to the other bits run in thedeeper part of the hole (over 7800 ft), the ROP increase was157%.

In reviewing the run parameters in Figure 8, it can be seen thatthe coated bit was run with lower flow rates and lower WOBthan previous PDC bit runs. This indicates that in these casesWOB and flow rate had only a limited effect on bit ballingwhen compared to the use of flouropolymer coatings. Theprevious PDC bits had been run with TFA from 1.75 to ashigh as 3.21 sq. inch, but all suffered from bit balling. Thepolymer-coated bit did not suffer from bit balling with 1.74 sq.inch TFA, and at lower flow rates.

The effect of bit balling increased, and ROP decreased, asmud weight increased from 9.2 to 10.3 ppg. However with theexperimental coated bit, balling was avoided even with as highas 10.6 ppg mud weight. The conclusion that has beenreached from this case study is that good bit hydraulic design,combined with coating the bit surface with a flouropolymer toprevent the shale from initially attaching to the bit surface,seem to be key factors.

Comparison with AB-ProcessOn the previous Tembungo B8 well, at similar depths (below10,000 ft), a bit had been run with an anti-balling electricalcharge surface treatment (described earlier). The comparisonis shown in Figure 10. At similar depths, and in the sameformations, 51 fph was achieved using the steel-body bit withthe anti-balling surface charge process. This ROP had been asignificant improvement over previous bit performance, butwas exceeded by 50%, using the flouropolymer-coated PDCbit. The latter initially drilled at 101 fph and achieved anaverage ROP of 72 fph over the full interval.

Durability of Flouropolymer CoatingFigure 11 shows that very little of the polymer coatingremained on the bit after it had reached hole section TD. Bynature, flouropolymers are soft. The reinforcement toughensit and allows it to remain on the bit for a much longer periodof time. However, if the bit is drilled through a substantiallayer of sandstone or other hard rock, the coating will abradeoff. Further enhancements made since this April, 2000 testmake the coating substantially more durable, but toughnesswill always be an issue with flouropolymer coatings. It is

important for any operator to judge the value of any coating orbit enhancement, not on the condition of the surface treatmentat the conclusion of the run, but on the economics: in this case,doubling ROP and finishing the interval. The coatingremained on the bit long enough in this case study to make asubstantial postive impact on the average run ROP.

Economics of Polymer Coated BitsThe first six bits used in the 12 hole section of TembungoB9 drilled the 4003 ft interval in 108 hours. At a spread costof $70,000US per day, this is equivalent to $79US per ft. Thefinal 1402 ft were drilled in 19.4 hrs with the reinforcedflouropolymer-coated PDC bit, costing $40US per ft. Thisrepresents a saving of $39US per ft. Applying these savingsto the first 4003-ft of the interval would have saved$156,000US in drilling time. (See Figure 12) Additionally, ifthree coated bits had drilled the interval rather than theprevious 6 bits, 4 bit trips (assuming 1000 ft/hr) would havesaved roughly 64 hours and another $187,000US. It is alsopossible that, using coated bits higher in the hole in the easierdrilling section, penetration rates and net cost savings couldhave even been higher.

Other Field Testing Experience of ReinforcedFlouropolymer CoatingSince April, 2000, when Petronas Carigali first utilized areinforced flouropolymer coating to reduce ROP in stickyshale formations in Malaysia, the technology has been testedworldwide and been commercialized for general usage. Theadded cost of the coating is small relative to the total bit cost,whereas the potential benefit is substantial. Figure 13highlights ROP improvements of from 27% to 107% fromAfrica to Argentina, Israel to Indonesia among others.Through 31 October 2001, more than 70 bits have been coatedwith the new product.

Summary1. A new reinforced flouropolymer PDC bit surface coating

has been developed and is now commercially available.2. The new proprietary coating reduced axial force by 25%

and tangential force by 15% in single point cutter testing.3. Baseline developmental testing of the coating on a 6

PDC bit in a drilling simulator at downhole conditionsgave a 500% ROP improvement over an uncoated bit.This magnitude of improvement may have been tied tothe particular bit type.

4. Simulator tests of flouropolymer-coated 8 and 8 PDC bits at up to 16 ppg mud prevented balling up to theROP capacity of the equipment, whereas the uncoated bitsballed at 175-200 fph.

5. In a Case Study from Petronas Carigali in offshoreMalaysia, a 12 IADC Type 323 PDC bit did not ballwith shale and doubled the average penetration rate of theprevious six bits, which had experienced balling.

6. In the Case Study, the flouropolymer showed 50% ROPimprovement over a different suppliers anti-balling (AB)process through the same hole section on the previous


well.7. In the Case Study, the coated bit saved the operator $39

per foot in drilling time over the average of the previoussix bits run in the well for a total savings of $156,000.Avoided bit trips would likely have provided additioinalsavings.

8. More than 70 total bits have been successfully coatedwith the new reinforced flouropolymer coating.

9. Coating durability is an issue although at least one bit hasdrilled over 7,600 ft with some coating surviving.Coating typically will be stripped off of bits drilledthrough significant abrasive formations.

10. Success of using flouropolymer-coated bits should bejudged on improved rate of penetration, not on the finalcondition of the coating.

ConclusionSubstantial drilling penetration rate improvements have beenexhibited in areas around the world with a unique newreinforced flouropolymer bit coating now available tooperators. Though a relatively small part of the overall bitcost, its use has the potential of saving the oil and gas drillingindustry millions of dollars through preventing bit balling incommon difficult shale formations.

AcknowledgmentsThe authors would like to thank Petronas Carigali and HughesChristensen for supporting this project and allowing data to beused. We also want to thank Neil Hudson and CraigFlemming for their contributions.

References(1) van Oort, E., Bland, R., Pessier, R., Drilling More Stable

Wells Faster and Cheaper with PDC Bits and WaterBased Muds, IADC/SPE Paper 59192, presented at the2000 IADC/SPE Drilling Conference, New Orleans, Feb.23-25.

(2) Smith, J.R., Diagnosis of Poor PDC Bit Performance inDeep Shales, PhD Dissertation, Louisiana StateUniversity, August, 1998, p. 347.

(3) Smith, R.H., Lund, J.B., Anderson, M., Baxter, R.,Drilling Plastic Formations Using Highly Polished PDCCutters, SPE 30476, presented at 1995 SPE AnnualConference, Dallas, Oct. 22-25.

(4) Smith, John Rogers, Performance Analysis of Deep PDCBit Runs in Water-Based Muds, ETCE2000/Drill-10123,presented at ETCE/OMAE2000 Conference, NewOrleans, Feb. 14-17.

(5) Zijsling, D.H., Illerhaus, R., Eggbeater PDC DesignConcept Eliminates Drilling in Water Based DrillingFluids, SPE Paper 21933 presented at the 1991SPE/IADC Drilling Conference, Amsterdam, March 11-14.

(6) Bland, R.G., Halliday, B., Illerhaus, R., Isbell, M.,McDonald, S., Pessier, R., Drilling Fluid and BitEnhancements for Drilling Shales, AADE Paper

presented at the 2000 Annual Technical Forum Improvements in Drilling Fluids Technology.

(7) Bland, R., Pessier, R., Isbell, M., Balling in Water-BasedMuds, AADE 01-NC-HO-56 Paper presented at the 2001AADE National Drilling Conference, Houston, March 27-29.

NOTE: Teflon is a registered trademark of E.I. duPontNemours and Company


Figure 1: Improvement over Bare Steel with Teflon and Ni/Tef Coatings

Figure 2: Simulator Testing of Various Coatings on IADC M332 PDC Bit

Single-Point Cutter Test Machine with Water as Test Fluid

(no PDC cutter, 10o backrake, 9000 psi confining pressure,

.011" depth of cut, 273 rpm)

-10.0%

0.0%

10.0%

20.0%

30.0%

BLTe

flon

GRTe

flon

Ni/T

ef

Ni/T

ef

Pe

rce

nt

De

cre

ase

with

T

eflo

n C

oa

ting

Axial Force Tangential Force Coefficient of Friction

6 1/2" IADC M332 PDC Bit WBM - 9.5 ppgSimulator Testing in Catoosa Shale: 250 gpm / 240 rpm / 1.0 hsi

0

30

60

90

0 1 2 3 4 5 6 7 8 9

Weight on Bit (kip)

RO

P (

fph)

Baseline -Uncoated Bit 9901B Plastic/Teflon

CK 54 9901E 9901F

Comm01 Nickel-Teflon Plating


Figure 3: Performance of Coated vs. Uncoated 8 IADC M323 PDC Bit

Figure 4: Performance of Coated vs. Uncoated 8 IADC 223 PDC Bit

6,000 psi Downhole Simulator: 445 gpm, 2.0 hsi, 120 rpm 9.5 ppg FW /CLS W ater-Based Mud in Catoosa Shale

0

50

100

150

200

250

300

0 5 10 15 20 25WOB (kip)

RO

P (

ft/h

r)

Coated - ROP

Uncoated - ROP

6,000 psi Simulator, Catoosa Shale: 466 gpm, 5.0 hsi, 120 rpm, 16 ppg FW/CLS WB Mud w/5% Drilling Enhancer

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35

WOB (kip)

RO

P (

ft/h

r)

Uncoated Bit

Coated Bit


Figure 5: Typical PDC Bit Coated with Figure 6: IADC Type M323 used in Case Prototype Reinforced Flouropolymer Study on Tembungo B9 (before coating)

Figure 7: Map of Location of Case Study: Tembungo Western Area

Tembungo FieldLocation


Table of Test Parameters and Conditions

Well Petronas Carigali Tembungo B9

Depth 6,122 11,527 ft

RPM 200-275 total

Mud Type Water-based KCL/PHPA Glycol (no ROP-enhancers added)

Mud Properties 18-20 PV; 17-22 YP; 8.5-9.3 pH

PDC Bits Used in 12 Interval of Tembungo B9

Bit Mfgr. Vendor S Vendor H Vendor D Vendor S HCC

IADC Type M123 M223 M223 M123 M323

Coated? No No No No Yes

TFA (sq in) 1.75 1.86 2.53 3.21 1.74

Depth In (ft) 6122 7787 8956 9432 10125

Footage (ft) 1665 652 476 21 1402

Drlg Hours 24.7 15.0 16.0 2.1 19.4

ROP (fph) 67.4 43.5 29.8 10.0 72.3

Flow (gpm) 840-920 885-920 840-925 800-880 750-800

WOB (kip) 5-50 2-15 6-37 8-23 8-15

Well Angle 48.8 47.7 41.7 40.8 31.9

MWt (ppg) 9.2-9.7 9.7-9.8 10.2-10.3 10.3 10.3-10.6

Figure 8: Table of Test Parameters and Conditions for Case Study


Tembungo B9 Bit ROP vs Depth

0

10

20

30

40

50

60

70

80

6000 7000 8000 9000 10000 11000 12000

Depth (ft)

Ave

rag

e R

OP

(fp

h)

PDC IADC M123

PDC IADC M223

Roller Cone IADC 4.3.5

PDC IADC M223

PDC IADC M123


Coated PDC IADC M323

Figure 9: Penetration Rate Improvement with Flouropolymer-Coated Bit

Figure 10: Comparison between Two Anti-Balling Processes

ROP in Deep Hole over 9,000 ft.Tembungo B9 vs B8

0

10

20

30

40

50

60

70

80

90

9000 10000 11000 12000

Depth (ft)

Ave

rag

e R

OP

(fp

h)

Tembungo B8Tembungo B9

HCC PDC IADC M323 PolymerCoated

Security PDC IADC S323 w/Anti-Balling Process

PDC IADC M123


PDC IADC M123


Figure 11: Photograph of Flouropolymer Coated Bit after Run

Figure 12: Comparison of Drilling Cost per Foot between Polymer-Coated and Uncoated Bits

0

10

20

30

40

50

60

70

80

Cost per Foot(US $)

Average of Previous Six Bits Used Polymer-coated Bit

Tembungo B9 Drilling Costs

$

$


Location Coated BitStyle

IntervalDrilled (ft)

AverageROP (fph)

Average Improvement overComparable Offsets

Israel(Gaza Marine 1)

20 DOSRWD 945 73 107%

Abu Dhabi(BAB Field)

12 IADC M121

(Note 1)

2545 292 50% (Note 2)

Abu Dhabi(W. Mubarraz)

12 IADC M121

(Note 1)

527 87 71% (Note 2)

Thailand(Bongkot)

8 IADC M122

(Note 1)

3729 199 55%

Indonesia(Attaka Field)

8 IADC M122

(Note 1)

7122 134 63%

Argentina(Can. Leon)

8 IADC M122

(Note 1)

543 53 44%

Nigeria(MEJI)

8 IADC M323

5222 (Note 3)

94 27%

Notes1. The improved ROP in most cases is attributable to both improved bit design (cutter layout,

hydraulics, and junk slot improvement) plus the reinforced flouropolymer coating.2. Improvement over other bit suppliers patented AB Anti-Balling Coating3. This was the second run on the bit. First was 2452 ft at 65 fph in an earlier well. Bit was not

re-coated between runs. Some coating was still visible after total of 7,674 ft. of drilling.

Figure 13: Selected Worldwide Field Testing ResultsOf New Reinforced Flouropolymer Coating on PDC Bits

IntroductionBackgroundCauses and Prevention of Bit BallingCoating DevelopmentSimulator Testing of Two Commercial Bits

Case Study: MalaysiaCase Study DetailsCase Study ResultsComparison with AB-ProcessDurability of Flouropolymer Coating

SummaryConclusion

AcknowledgmentsReferencesFigure 1: Improvement over Bare Steel with Teflon and Ni/Tef CoatingsFigure 2: Simulator Testing of Various Coatings on IADC M332 PDC BitFigure 3: Performance of Coated vs. Uncoated 8 Figure 4: Performance of Coated vs. Uncoated 8 Figure 7: Map of Location of Case Study: Tembungo Western Area

PDC Bits Used in 12 Interval of Tembungo B9YesFigure 10: Comparison between Two Anti-Balling ProcessesFigure 11: Photograph of Flouropolymer Coated Bit after Run

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