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HYDRAULICS
PetroSkills
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Hydraulics Hydraulics can be maximized using the
horsepower method or the impact forcemethod
2
1714PQHp=
1932
QVIF nm
=
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Hydraulics In the Pressure Loss chapter, we learned
that
dcadpabitdcdpsurfs PPPPPPP +++++=
3
to Pc yields
bitcs PPP+=
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Hydraulics Pressure losses in the circulating system
(everything except the bit) can also beexpressed as:
sc KQP =
4
Where Kis a constant and s is the slope of a
line on loglog paper
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Hydraulics You can also say that:
Substituting Equation 71 into Equation 75
bitcs HpHpHp +=
5
714,1714,1714,1
QPQPQP bitcs+=
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Hydraulics Rearranging and canceling the 1,714:
Substituting Equation 74 into Equation 77:QPQPQP csbit =
6
=sbit
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Hydraulics Differentiating and setting equal to zero:
Minimum
Maximum
0=bitP
7
0)1( =+ ss KQsP
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Hydraulics Substituting Equation 74 into Equation 7
10:0)1( =+ cs PsP
8
cs PsP )1( +=
sc Ps
P
+
=
1
1
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Hydraulics The horsepower at the bit will be
maximized when
1
9
sc
s +1
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Hydraulics If the slope s is assumed to be 1.86 (the
industry usually assumes between 1.80 and1.86), the equations become:
10
sc PP 35.0=
sbit PP 65.0=
sc PP
+
=
186.1
1
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Hydraulics Hydraulic horsepower will be maximized
when the pressure losses in the circulatingsystem are 35% of the maximum allowable
standpipe pressure and the pressure losses
11
at the bit are 65% of the maximumallowable standpipe pressure
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Hydraulics Example 72 derives the equation for the
maximum impact force Equation 717 can be used to calculate the
pressure drop across the bit nozzles
12
120,1
2nm
bit
VP
=
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Hydraulics Substituting Equation 73 and 74 into
Equation 717 yields:
ss
nm KQPV
=
2
13
Rearranging Equation 718:
,
( )2
1
120,1
=
m
ss
n
KQPV
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Hydraulics Substituting Equation 716 into Equation 7
19
( )2/1
s
sm KQPQ
14
Simplifying:
120,1932,1
m
[ ] 2/122 += ss AKQQAPIF
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Hydraulics whereA is a constant equal to
Differentiating and setting equal to zero333,3
m
A
=
15
[ ]dQ
AKQQAPd
dQ
IFds
s
2/122)(
+
=
[ ] [ ]12/122 )2(22
10 +
+
+=s
ss
s AKQsQAPAKQQAP
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Hydraulics
1)2(20 ++= ss KQsAQAP
QPsAQAP cs )2(20+=
cs PsP )2(20 +=
16

maximizing impact force at the bit
sc P
s
P
+
=
2
2
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Hydraulics Again, assuming the slope is 1.86, the
impact force will be maximized when
17
sc PP 52.0=
sbit PP 48.0=
sc PP +=
286.1
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Hydraulics Impact force will be maximized when the
pressure losses in the circulating system are52% of the maximum allowable standpipe
pressure and the pressure losses at the bit
18
are 48% of the maximum allowablestandpipe pressure
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Hydraulics
Keeping the same
surface pressure Ps,
the flow rate canbe varied and HP
and IF can be 800
1000
1200
1400
IMPACT FORCE
calculated
The maximum
values can befound0
200
400
600
0 100 200 300 400 500 600 700
Flow Rate, Q
Hp
orI
HORSEPOWER
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Directional Drilling
PetroSkills
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Introduction
Type I is a build and
holdDrilled to a relatively
shallow KOP
Deflected to amaximum inclination
The inclination is held
relatively constant toTD
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Introduction
Type II is a build
hold and dropoften termed an
S curve
Multiple targetsAround salt domes
More torque and
drag for the samedeparture
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Introduction
Type III is a
continuous build totarget
Deeper kickoff point
Small horizontaldeparture
Less expensive
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Introduction
Type IV is a
horizontal wellboreBuild rates may behigh
Hold inclination isnear 90 degrees
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DesignerWell
00
252500500500
750750
10001000
15001500
12501250
17501750TrueVerticalDepth(m)
TrueVerticalDepth(m)
ERD Wells withERD Wells withsignificantsignificant
azimuthazimuth
change(s)change(s)
20002000
22502250
FinalFinalWellboreWellbore
PilotPilot HoleHole
HighlyHighlyengineered wellengineered well
plan requiredplan required
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Introduction
26
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Introduction
27
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Survey Calculations
Common
terminology for a
directional profileEOB or EOCEOB or EOC
KOPKOP
Build SectionBuild Section
RKBRKB
ftf
t
Departure, ftDeparture, ft
Tangent or HoldTangent or Hold
DropDrop
SectionSection
TVD,
TVD,
Build rate angle (BRA, Drop rate angle (DRA)
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Survey Calculations Dogleg severity is a measure of the amount of
change in the inclination and/or azimuth of aborehole, usually expressed in degrees per
29
length
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Survey Calculations IfI1 = 2
o, I2 = 4o and MD = 100, then the
dogleg severity would be( )
'100/2100
24 0=
=DLS
30
IfI1 = 2o, I2 = 4
o and MD = 50, then the
dogleg severity would be
( )'100/4
2
2
50
24 0=
= xDLS
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Survey Calculations Most common survey methods
TangentialBalanced Tangential
Average Angle
31
Radius of CurvatureMinimum Curvature
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Survey Calculations
Tangential method uses only the lower
survey point and is the least accurate
survey method
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Survey Calculations The balanced tangential survey methodassumes the wellbore course is two straightlines with half the wellbore course tangentto the upper survey point and the otherhalf to the lower survey point
33
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Survey Calculations The average angle method assumes the
wellbore course is a straight line tangent to
the average angle
34
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Survey Calculations Radius of curvature assumes that the
wellbore course is an arc of a circle
Used for planning but not for final survey
35
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Survey Calculations Minimum Curvature is the balanced
tangential method but the straight lines are
smoothed into an arc by a correction factor
36