Bit Selection
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Transcript of Bit Selection
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