06 Pressure Losses

8/11/2019 06 Pressure Losses

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2005 PetroSkills LLC, All Rights Reserved

PRESSURE LOSSES

The pressure losses within a well

are reflected in the standpipe

pressure


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2005 PetroSkills LLC, All Rights Reserved2

Pressure Losses

Pressure lossesare the sum of all

pressure losses in

the system

dcadpabitdcdpsurfs PPPPPPP


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Pressure Losses

The majority of the pressurelosses in the circulating system

are in turbulent flow

Surface connections, drill pipe,

drill collars and bit


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Pressure Losses

The velocityvectors are not

ordered and the

velocity profile isvery flat with the

average velocity

approximatelyequal to the

maximum velocity


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Pressure Losses

This is the classicFanning Friction

Factor Diagram

The friction factoris a function of the

roughness of the

pipe and theReynolds number


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Pressure Losses

The Reynolds number can bedetermined from the following

equation

In turbulent flow the viscosity is

me

vDR 47.15

2.3

PV


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Pressure Losses

e/D comes from the

Moody Diagram1. Cast Iron

2. Galvanized Iron

3. Asphalted CastIron

4. Commercial

Steel or Wrought Iron5. Drawn Tubing

0.000010

0.000100

0.001000

0.010000

0.100000

1 10 100

Pipe diameter, inches

e/D

Riveted Steel

Concrete

e=0.03

e=0.01

e=0.003

e=0.001e=0.00085

e=0.0005

e=0.0004

e=0.00015

e=0.000005

1

2

3

4

5



Pressure Losses

The frictional pressure loss isrelated to the friction factor by

the following equation

e/D is 0.0006 if you assume 4 IDsteel and the friction factor

would be

D

lfvP m

)10(298.9 4

2



Pressure Losses

By substituting into the equationfor pressure losses, one can

determine the pressure losses

inside pipefor turbulent flow

19.00458.0

eR

f



Pressure Losses

In this class we will use Equation6-6for turbulent flow in pipe

It includes pressure losses in the

surface connections, drill pipeand drill collars

83.4

19.081.181.05 )10(68.7

D

lPVQP m



Pressure Losses

Classes of surface equipment

COMPONENTS - LENGTH AND ID

CLASS # STANDPIPE HOSE SWIVEL KELLY

1 40' - 3" 45' - 2" 20' - 2" 40' - 2 1/4"

2 40' - 3 1/2" 55' - 2 1/2" 25' - 2 1/2" 40' - 3 1/4"

3 45' - 4" 55' - 3" 25' - 2 1/4" 40' - 3 1/4"

4 45' - 4" 55' - 3" 30' - 3" 40' - 4"



Pressure Losses

Example 6-1

Total Depth 17,193 feet (5240m)Hole Size 6 1/2 inches (165mm)

Rheology in Figure 4-16 and Table 4-5 of theDrilling Fluids Chapter

BHA 818 ft (249m). 4.8" OD (122mm) by 1 1/2" ID(38mm) DCs

Drill pipe 3 1/2" 15.5 #/ft, ID = 2.602 (89 by66mm)

Drill pipe length is 16, 375 feet (4991m)Surface Equipment is Class 2

Nozzles 2-11 and 1-12 (2-8.7mm and 1-9.5mm)

Drilling with 147 gpm at 3100 psi (0.556m3at

21,370 kPa)



Pressure Losses

Calculate pressure losses in thesurface connections using

Equation 6-6

Standpipe

Hose

psi1)5.3(

)40()29()147()15)(10(68.783.4

19.081.181.05

P

psi7)5.2(

)55()29()147()15)(10(68.783.4

19.081.181.05

P

(7 kPa)

(48 kPa)



Pressure Losses

Swivel

Kelly

Total

psi3)5.2(

)25()29()147()15)(10(68.783.4

19.081.181.05

P

psi1)25.3(

)40()29()147()15)(10(68.783.4

19.081.181.05

P

psi121371 surfP

(21 kPa)

(7 kPa)

(83 kPa)



Pressure Losses

Pressure losses in surfaceconnections are small and not

worth calculating unless done on

a computer



Pressure Losses

Calculate the pressure losses inthe drill pipe using Equation 6-6

psi1766)602.2(

)16375()29()147()15)(10(68.7

83.4

19.081.181.05

dpP

(12,180 kPa)

83.4

19.081.181.0

5 )10(68.7D

lPVQP m



Pressure Losses

Calculate pressure losses in thedrill collars using Equation 6-6

Pdc 7 68 10 15 147 29 818

1 51262

5 0 81 1 81 0 19

4 83

. ( )( ) ( ) ( ) ( )

( . )

. . .

.psi

(8700 kPa)

83.4

19.081.181.05 )10(68.7

D

lPVQ

P m



Pressure Losses

In this class, we will assume thatpressure losses in the drill string

are always turbulent which they

will be under almost anycircumstance



Pressure Losses

Equation 6-11is for pressurelosses through the jet nozzles

The pressure loss is based onthe change in kinetic energy

2

25

)10(14.9n

mbitA

QP



Pressure Losses

Example 6-2calculate thepressure loss through the jet

nozzles for the given well

23

22

214/ SSSAn

2222

in2961.032

12

32

11

32

11

4/

nA (7.52 mm2)



Pressure Losses

psi338

)2961.0(

)147)(15)(10(14.92

25

bitP (2330 kPa)

2

25 )10(14.9

n

mbit

A

QP



Pressure Losses

Laminar flow is a smoothordered flow

Distinguishing between turbulent

and laminar flow has always

been a problem

With classic fluids such aswater, turbulence occurs at a

Reynolds Number of 2000



Pressure Losses

With non-Newtonian fluids, thetransition can occur anywhere

between Reynolds Number of

2000 to 4000


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Pressure Losses

Equation 6-14 is assumed to bethe break over between laminar

and turbulent flow at a Reynolds

Number of 2000

n

n

ph

n

m n

n

DD

kV

22

14

2000

3

124.2)10(59.2


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Pressure Losses

Example 6-3Determine thecritical velocity in the drill pipe

annulus

fpm212)43.0)(3(1)43.0)(2(

5.35.64.2

15)45.2)(10(59.2 43.02

43.0

43.02

14

2000

V

(64.6 m/min)

nn

ph

n

m n

n

DD

kV

22

14

20003

124.2)10(59.2


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Pressure Losses

The annular velocity is

)(

5.2422

ph DD

Qv

fpm120)5.35.6(

)147)(5.24(22

v (36.6 m/min)


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Pressure Losses

Can calculatefriction in both

laminar and

turbulent flowWhichever is

greater is

correct

P


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Pressure Losses

For this class, we will assumethat the flow in the annulusis

always laminarand we will use

the power-law modelforcalculations

P L


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Pressure Losses

Equation 6-22is used for power-law and laminar flow in the

annulus

)(3003

124.2

ph

n

ph DD

kl

n

n

DD

vP

P L


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Pressure Losses

Example 6-4calculate frictionlosses in the annulus

Drill pipe

psi371)5.35.6(300)16375)(45.2(

)43.0)(3(1)43.0)(2(

5.35.6)120)(4.2(

43.0

dpaP

(2560 kPa)

)(3003

124.2

ph

n

ph DD

kl

n

n

DD

vP

P L


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Pressure Losses

Drill collars

psi51)8.45.6(300

)818)(45.2(

)43.0)(3(

1)43.0)(2(

8.45.6

)187)(4.2(43.0

dcaP

(350 kPa)

)(3003

124.2

ph

n

ph DD

kl

n

n

DD

vP

P L


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Pressure Losses

All the friction losses are addedtogether to determine the

standpipe pressure

P L


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Pressure Losses

In Example 6-4, it is assumedthat the pipe is hydraulically

smooth and the standpipe

pressure is equal to

psi3594513713381157166512 sP

(24,780 kPa)

dcadpabitdcdpsurfs PPPPPPP

P L


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Pressure Losses

The actual standpipe pressurewas 3100 psi

The calculated pressure does

not agree with the actual

pressure due to accuracy of the

equations, accuracy of the

standpipe gauge and estimated

pump efficiency

P L


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Pressure Losses

Usually assume 95% to 98%

volumetric efficiency for triplex

pumps and 85% to 90%

volumetric efficiency for duplexpumps

P L


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Pressure Losses

If the difference between actualand calculated standpipe

pressure is assumed to be pump

accuracy, the actual pumpefficiency can be determined

Friction losses in the system

should be a straight line on a

piece of loglog graph paper

P L


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Pressure Losses

By plotting pressure lossesversus flow rate, the flow ratecan be determined from theactual standpipe pressure

An arbitrary flow rate of 100 gpm(0.379 m3/min) was chosen forthe second point on the graph

and the calculated standpipepressure was 1942 psi (13,390kPa)

P L


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Pressure Losses

At a standpipe

pressure of3100 psi(21,370 kPa),the calculated

flow ratewould be 134gpm (0.507

m

3

/min) or apumpefficiency of92%

3100

134

Pressure Losses


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Pressure Losses

ECDEquivalent circulatingdensity

A way of expressing friction losses in

the annulus

Expressed in terms of additional mud

weight

Convert the friction losses to a mudweight and add to the mud weight

Pressure Losses


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Pressure Losses

Equation 6-25is used tocalculate ECD

The ECD at any point can be

calculated based on the frictionlosses downstream of that point

TVD

PP

ECD

dcadpa

m 052.0

Pressure Losses


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Pressure Losses

Example 6-5 calculates the ECDfor the well

TVD

PP

ECD

dcadpa

m 052.0

ppg47.15

17193052.0

5137115

ECD (1856 kg/m3)

Pressure Losses


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Pressure Losses

Class ProblemThe casing seat in the example well

is at 15,500 feet (4724m)

Calculate the ECD at the casing seat

Pressure Losses


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Pressure Losses

Answers

The friction loss in 16,375 feet(4991m) of drill pipe annulus is 371psi (2558 kPa)

Since friction losses are linear, thefriction loss per foot can be calculatedas follows:

371 psi / 16,375 feet = 0.0227 psi/ft(0.5125 kPa/m)

Friction at 15,500 feet (4724m) is:

0.0227 x 15,500 = 351 psi (2421 kPa)

Pressure Losses


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Pressure Losses

Calculate friction losses in theannulus

Drill pipe

psi351)5.35.6(300

)15500)(45.2(

)43.0)(3(

1)43.0)(2(

5.35.6

)120)(4.2(43.0

dpaP

(2420 kPa)

Pressure Losses


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Pressure Losses

The ECD can be calculated

ppg44.15

15500052.0

35115 ECD (1853 kPa)

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06 Pressure Losses