Drill Bit Selection

Objectives

F Bit Selection Processes

Which Bit to Choose?Which Bit to Choose?

F Roller Cone or Fixed Cutter?F If Roller Cone:

l Steel teeth or tungsten carbide inserts?l Projection and Pitch of teeth / inserts?l Journal bearing or roller bearings?

F If Fixed Cutter:l PDC or natural diamonds?l Cutter size & shape?l Number of blades, hydraulics, bit profile?

Bit selection is at the heart of a processthat begins and ends with the customer

GeologyInfluenceRock TypeStrength

AbrasivenessStickiness

ParametersRecommendation

Gather Data:

Offset Bit Records

Well PrognosisMud ProgramDirectional Plan

Offset FRR’ sMud LogsElectric Logs

Analyze Data

Request

CUSTOMER

Drilling FluidsInfluence

Mud TypeMud Weight

PriorDrilling History

Bit types usedPerformance standardsTypes of vibration

Well Program

Summaryof

Well Data

BitRecommendationsPredicted

Performance

OperatingParameters

Hydraulics EconomicsCalculation

OffsetInformation

ProductInformation

Pricing

Directional DrillingInfluence

Build & Walk rate reqd.Tangent angle

Drive type

BIT SELECTION

Bit Selection Process OverviewBit Selection Process Overview

Selection ProcessSelection Process

F Applicationsl geological knowledge is essentiall enhanced selection process using offset bit records, well log

Analysis / GeoMechanicsl bit selection should meet actual criteria necessary to fail

specific rock types and satisfy the cleaning requirements

Bit Selection Process - DetailsBit Selection Process - Details

F Collect datal geologyl offset bit records, mud logs, well logs

F Analyze the proposed well planl length of hole sections, drill out casing?l drilling fluidsl directional drilling objectivesl geology

Bit Selection Process (continued)Bit Selection Process (continued)

F Consider the rock’s propertiesl hardness / drillability / compressive strengthl abrasivenessl stickiness

F Determine the “Engineering Classification” for the rock

F Identify best candidates from the “Roller Cone Bit Selection Table” and offsets

Bit Selection Process (continued)Bit Selection Process (continued)

F Identify opportunity for fixed cutter bitl use “Fixed Cutter Selection Table”l PDC, TSP or diamond?

F Make an economic forecastl cost per footl breakeven analysis

F Select the bitF Check and fine-tune answer

Estimating Compressive Strength of the Rock

Estimating Compressive Strength of the Rock

F Provide offset logs to Security DBSl sonic log, density log, porosity logl gammal mud log

F Security DBS performs “GeoMechanics” analysisF Results in a computed “strength log”F Strength values matched to bits

Engineering Classification for “Intact” Rock

Engineering Classification for “Intact” Rock

Classification

Very Low Strength

Low Strength

Medium Strength

High Strength

Very High Strength

Compressive

Strength, psi

< 4000

4000 - 8000

8000 - 16000

16000 - 32000

> 32000

> 70

35 -70

15 - 35

5 -15

< 5

ROP

ft/hr

Engineering Classification for “Intact” Rock

Engineering Classification for “Intact” Rock

Classification

Very Low Strength

Low Strength

Medium Strength

High Strength

Very High Strength

Compressive

Strength, MPa

< 27.6

27.6 - 55.2

55.2 - 110.4

110.4 - 220.8

>220.8

> 21.3

10.7 - 21.3

4.6 - 10.7

1.5 - 4.6

< 1.5

ROP

m/h

Classification

Very Low Strength

Low Strength

Medium Strength

High Strength

Very High Strength

Milled Tooth

codes

TCI

codes

1xx

1xx - 2xx

2xx - 3xx

3xx

n/a

N/A

4xx - 5xx

5xx - 6xx

6xx - 7xx

8xx

Roller Bit Selection TableRoller Bit Selection TableIADC CODES

Identify Opportunities for PDC Drill Bits

Identify Opportunities for PDC Drill Bits

F Potential PDC Applicationsl long shale, mudstone or claystone sectionsl chalk, limestone, salts and anhydritel gumbo shales with oil based mudl researched sandstone intervalsl absence of hard, well cemented, angular abrasive sandsl absence of chert, pyrite, quartzitel motor/turbine drilling (high RPM)

Identify Opportunities for Natural Diamond / Impregnated Drill BitsIdentify Opportunities for Natural Diamond / Impregnated Drill Bits

l hard siltstones, sandstonesl hard limestone, dolomite,l motor or turbine drilling (high RPM) l roller bit ROP < 6 ft/hour (1.8 m/h)l roller bit footage < 50 ft (15 m) per run

Economics of Bit ApplicationsEconomics of Bit Applications

F Cost of the drill bit is not the concern !F Performance is more important

l projected ROPl projected footage

F Relevant cost parameter is “Cost per Foot” l includes raw bit costl daily operations cost dominatesl trip time must be considered

bit cost + rig rate (trip time + rotating time)footage drilled

CPF =

CPF = (C + R ( t + T )) / F

•Where:

• bit cost, C, is in dollars

• rig rate, R, is in dollars per hour

• trip time, t, and rotating time, T, are in hours

• footage drilled, F, is measured in feet

Cost per Foot (CPF)Cost per Foot (CPF)

Where:

C bit cost, RubelsR rig rate, Rubels/hourt trip time, hourT rotating time, hour L meters drilled, meter

Cost per Meter (CPM)Cost per Meter (CPM)

bit cost + rig rate (trip time + rotating time)length drilledCPM =

CPM = LC + R(t+T) Rub/m

Bit Selection Process - SummaryBit Selection Process - Summary

F Collect all necessary offset dataF Perform GeoMechanics AnalysisF Identify bit types for all intervals to be drilled F Identify any PDC bit applicationsF Make an economic forecast

l cost per footl breakeven analysis

F Select the bitsF Build bit program, operating parameters, hydraulics

Thank youThank youThank you