1B - Drilling Cost and Drilling Rate
1B - Drilling Cost and Drilling Rate
1B - Drilling Cost and Drilling Rate
1
Contents
Ø The AFE
Ø Drilling Cost and Bit Change
Ø Factors Affecting Drilling Rate
Ø Bit Weight, Rotary Speed
Ø Bottom-hole Cleaning
Ø Mud Properties, Solids Content
Ø HW #. ADE 1.12, 1.13, 1.14
2
Before getting approval to drill a well the
Drilling Engineer must prepare an AFE
- a detailed cost estimate for the well
DRY COMPLETED
HOLE
INTANGIBLE COSTS $ $
TANGIBLE COSTS $ $
TOTAL COST $ $
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AUTHORIZATION FOR EXPENDITURE (AFE)
EXPENDITURE DRY HOLE COMPLETED
(24.5 DAYS) (32.5 DAYS)
INTANGIBLE COSTS
LOCATION PREPARATION 30,000 65,000
DRILLING RIG AND TOOLS 298,185 366,613
DRILLING FLUIDS 113,543 116,976
RENTAL EQUIPMENT 77,896 133,785
CEMENTING 49,535 54,369
SUPPORT SERVICES 152,285 275,648
TRANSPORTATION 70,200 83,400
SUPERVISION AND ADMIN. 23,282 30,791
SUB-TOTAL 814,928 1,126,581
TANGIBLE COSTS
TUBULAR EQUIPMENT 406,101 846,529
WELL HEAD EQUIPMENT 16,864 156,201
COMPLETION EQUIPMENT 0 15,717
SUB-TOTAL 422,965 1,018,447
DEPTH
ft
TD
DAYS or DOLLARS
5
Drilling Cost Analysis
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The Drilling Engineer
Ø pump operation
Ø bit selection
Cb + Cr( tb + tc + tt ) $
Cf = Eq. 1.16
DD ft
Cb + Cr( tb + tc + tt ) $
Cf =
DD ft
Cb + Cr( tb + tc + tt ) $
Cf =
DD ft
12
Solution, cont’d
Cb + Cr( tb + tc + tt ) $
Cf =
DD ft
14
Drilling Costs
C = aebD …………………..(1.17)
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Drilling Costs, cont’d C = aebD
1
td = ( e 2.303 a 2D - 1)......... .....( 1.19 )
2.303a 2K
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Drilling Time cont’d
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EXAMPLE - Cost per ft
t R D Total Cost Cf
hr fph ft $ $/ft
70
60
Minimum Cost
50
40
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Economic Procedure in above Table
25
An increase in
TORQUE may
indicate that a bit
should be pulled.
Experience often
dictates when to
pull bit (footage or
hours).
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Factors that affect Penetration Rate
Variables:
Ø Type of Drill bit
Ø Bit weight
Ø Rotary speed
Ø Bottom-hole cleaning
Ø Mud properties
Fixed Factors:
Ø Rock hardness
Ø Formation pore pressure
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Bit Selection is based on
28
Bit Weight and Rotary Speed
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40,000 lbf
Consider 10” hole
(don’t overdo!!)
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EFFECT OF BACK PRESSURE
0 - 5,000 psi
37