Directional Drilling Hydraulics

7/30/2019 Directional Drilling Hydraulics

1/36

HYDRAULICS

PetroSkills


2/36

Hydraulics Hydraulics can be maximized using the

horsepower method or the impact forcemethod

2

1714PQHp=

1932

QVIF nm

=


3/36

Hydraulics In the Pressure Loss chapter, we learned

that

dcadpabitdcdpsurfs PPPPPPP +++++=

3

to Pc yields

bitcs PPP+=


4/36

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 log-log paper


5/36

Hydraulics You can also say that:

Substituting Equation 7-1 into Equation 7-5

bitcs HpHpHp +=

5

714,1714,1714,1

QPQPQP bitcs+=


6/36

Hydraulics Rearranging and canceling the 1,714:

Substituting Equation 7-4 into Equation 7-7:QPQPQP csbit =

6

=sbit


7/36

Hydraulics Differentiating and setting equal to zero:

Minimum

Maximum

0=bitP

7

0)1( =+ ss KQsP


8/36

Hydraulics Substituting Equation 7-4 into Equation 7-

10:0)1( =+ cs PsP

8

cs PsP )1( +=

sc Ps

P

+

=

1

1


9/36

Hydraulics The horsepower at the bit will be

maximized when

1

9

sc

s +1


10/36

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


11/36

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


12/36

Hydraulics Example 7-2 derives the equation for the

maximum impact force Equation 7-17 can be used to calculate the

pressure drop across the bit nozzles

12

120,1

2nm

bit

VP

=


13/36

Hydraulics Substituting Equation 7-3 and 7-4 into

Equation 7-17 yields:

ss

nm KQPV

=

2

13

Rearranging Equation 7-18:

,

( )2

1

120,1

=

m

ss

n

KQPV


14/36

Hydraulics Substituting Equation 7-16 into Equation 7-

19

( )2/1

s

sm KQPQ

14

Simplifying:

120,1932,1

m

[ ] 2/122 += ss AKQQAPIF


15/36

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


16/36

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


17/36

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


18/36

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


19/36

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


20/36

Directional Drilling

PetroSkills


21/36

Introduction

Type I is a build and

holdDrilled to a relatively

shallow KOP

Deflected to amaximum inclination

The inclination is held

relatively constant toTD


22/36

Introduction

Type II is a build

hold and dropoften termed an

S curve

Multiple targetsAround salt domes

More torque and

drag for the samedeparture


23/36

Introduction

Type III is a

continuous build totarget

Deeper kickoff point

Small horizontaldeparture

Less expensive


24/36

Introduction

Type IV is a

horizontal wellboreBuild rates may behigh

Hold inclination isnear 90 degrees


25/36

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


26/36

Introduction

26


27/36

Introduction

27


28/36

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)


29/36

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


30/36

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


31/36

Survey Calculations Most common survey methods

TangentialBalanced Tangential

Average Angle

31

Radius of CurvatureMinimum Curvature


32/36

Survey Calculations

Tangential method uses only the lower

survey point and is the least accurate

survey method


33/36

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


34/36

Survey Calculations The average angle method assumes the

wellbore course is a straight line tangent to

the average angle

34


35/36

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


36/36

Survey Calculations Minimum Curvature is the balanced

tangential method but the straight lines are

smoothed into an arc by a correction factor

36

Directional Drilling Hydraulics

Documents