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Master In e neria del Petrolio 2006-2007

G R O U P

Stage Subject

Techniques of artificial lift for viscous oil

San Donato Milanese October the 22nd-23rd 2007

Author

In . Stefano Mazzone

Company Tutors

In . Roberto Fanciulli

Ing. Salvatore Pilone

University Tutor

Prof. Ing. Francesca Verga

Dept. SPEO/COMP


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Artificial lift techniques for viscous oils

Summar

9Description of traditional systems of artificial lift ( piston type

pumps, jet pumps, rod pumps, progressive cavity pumps, electricsubmersible pumps)

performance

performances in presence of heavy / viscous oils


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Medium Heavy Oil

c cmobile at reservoir conditions

Extra Heav Oil

20> API > 7 10 000 cP > > 100 cP

ar an s an umen

12> API > 7 > 10 000 cPnon mobile at reservoir conditions


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Artificial lift techniques Systems overview

Description of traditional systems of artificial

lift

Piston pumps Jet Pumps

Rod Pumps

Progressive Cavity Pumps - PCP Electric submersible pumps - ESP


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Hydraulic piston pumps

There are two types of piston pumps

exhausted power fluid to mix with the produced fluid

power fluid separated from the produced fluid

van ages

high pressure head good efficiency

sa van ages

low capacity power fluid solid control

depth up to 17.000 feet

resists to high temperatures

(300 -500F)

essential(to avoid excessive wear)


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y rau c e pumps

The Jet um has no movin arts. Power fluid water, crude oil or

diluent) at high pressure is supplied to the nozzle which converts thepressure head into a high velocity jet reducing the pressure in the

.

together in the throat, recover pressure in the diffuser and proceed

upwards.

Advantages

no movin arts low wear

suitable for low quality production fluids suitable for gassy wells

Disadvantages

hi h suction ressure to avoid cavitation high input horse power due to low efficiency (up to 30%)

possible emulsion former


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Rod Pumps

TubingThe um in ca acit of these devices de ends on

Connectionw/tubingstroke length, pumping speed, volumetric efficiency

(i.e. the percentage of pumps volume effectively

Plunger

.

economic

resists to high temperatures

Travelingvalve

Disadvanta es

Standing

Cage unsuitable for deviated wells

seal wear

Ball & seat

valve low depth (10,000 ft)


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A PCP is a positive displacement pump made up of a helical rotor.

from surface by rotating rods or by a bottom hole electric motor viaa gear reducer (max speed 500 rpm)

Advantages

-

suited for high viscous and/or abrasive fluids

works at high temperatures up to (300 F)

low capacity (max speed 500 rpm)

low ability to handle free gas (low efficiency)


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Electrical Submersible pumps

Submersible pumps are multi-staged centrifugal pumps.

Each stage consists of a rotating impeller and a stationary diffuser. The impeller imparts kinetic energy and some pressure head to the fluid

The diffuser converts some of the fluid kinetic energy into pressure headand directs it to the next sta e.

Stage after stage the total head required is obtained.

Advantages Disadvantages

high capacity good efficiency for high rates

depth limitations due to inputhorsepower limitation

sensitivit to hi h

good head

less than volumetric pumps

temperatures

gas locking problems


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ESPs typical curvesRev. A Fluid Specific Gravity 1.00Minimum Casing Size 6.625 inches OD Check Clearances

peet

60%

B.E.P.

Q = 5511H = 2833.84P = 173.95E = 66.12

6,000 600

50%5,000 500

30%

40%

3,000

4,000

300

400

20%2,000 200

10%1,000 100

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000

Capacity - Barrels per Day


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Artificial lift techniques

Summary



performance

performances in presence of heavy / viscous oils ( 8-20 API)


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Whats the problem?

ESPs performance is always evaluated

At moderate to high viscosity ESPs

increase of break horse power

head and capacity reduction


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Current correction methods

n y aws or ro a ona spee correc on

(applicable to inviscid fluids)

Hydraulic Institute charts,

tepanoff,

Turzo etc..


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9Tests based on single stage pumps handling viscous oils.

9 Equations used for corrections, when water performances are known :

BEP (Qw,Hw) Fluid viscosity

Qvis = CqQwHvis = ChHwvis = Cw

3960

vis

visvis QH

BHPvis =


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Turzo proposed the use of correlations

Cq = )2*4*3 10724.1100327.41 qq

C = ( )2*4*2 108875.2103075.31 qq +

Ch1 =

2*5*3

( )2*5*3 1036.41068.31 qq

=

Ch3 =

.. qq

2*5*3 1041.1100076.71 qq

Ch4 = ( )2*5*3 1031.11001.91 qq


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tepano s exper ments s owe t at at constant rotat ona spee t especific speed Ns (defined at the best efficiency point) remains constant

either um in viscous oil or water :

2/12/1

bepbep woilqNqN

.51=

2/3

oiloil Hq =4/34/3

bepbep woil

s

HH

Hq

ww Hq


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Defining a Reynolds number-likeas indipendent variable

Rstepanoff =w

oil

bepqN

oilbep

correction chart for head, capacityand efficiency at the B.E.P. :


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Artificial lift techniques

Summary



performance

performances in presence ofheavy / viscous oils ( 8-20 API)


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Comparison betweenwater design and oil design of an ESP for a viscous oil

(8 Api, 336 cp at T = 100C) :

Re uired arameters : Head = 782 feet Ca acit = 3336 RB/da

Size : 5,13Efficiency at the required point : 73%

Size : 5.13Efficiency at the required point : 15.9%

um er o stages :

BHP required : 26.1

Frequency : 50 Hz

Number of stages : 87

BHP required : 119.8

Fre uenc : 50 Hz


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Performances (31 stages)

1400

1000

1200

Water

Re uired oint

600

800

H(

feet)

200

400

0

0 1000 2000 3000 4000 5000 6000 7000

Q (RB/day)


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Oil design ( = 336 cp)

Performances (87 stages)

3500

4000 Turzo

2500

3000

Required point

Edvocia

1500

2000

H(

feet)

500

1000

0

0 1000 2000 3000 4000 5000 6000 7000

Q (RB/day)


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Excel sheet linking to ProsperQwbep (RB/d) 60Hz Hwbep (ft) 60Hz (cp) n (rpm) (sp. gr.) Cq Ch Qobep Hobep

4053.700 37.100 317.000 2897.981 0.962 0.718 0.802 2 425.491 640.412

stages Q req H req

Water erformance

Link to Prosper

. .

Pump Manufacturer Pump Name Size Cq Ch Qobep Hobep

CENTRILIFT E127 5.13 0.711 0.796 2401.034 636.100

EDVOCIA

0,6*Hwbep 0.8*Hwbep Hwbep 1.2*Hwbep Cq Ceff Ch1 Ch2

32.7 29.7 25.8 20.7 0.688 0.231 0.835 0.811

Ch3 Ch4 qcorrette hcorrette

Stepanoff

. . . .

1859.867 747.545

2324.833 605.459

2789.800 444.731

coefficients Q (RB/d) H (ft) Qmax 60 Hz RB/ Hz TURZO5.750E+01 0.000 1237.853 7200 50

-6.316E-03 315.789 1192.006

2.073E-06 631.579 1154.819

-6.431E-10 947.368 1122.691

Edvocia

Turzo

6.093E-14 1263.158 1092.576

-2.259E-18 1578.947 1061.940

1894.737 1028.717

2210.526 991.262

2526.316 948.304

2842.105 898.905

3157.895 842.409

3473.684 778.398

3789.474 706.651

Performances1500

w ater

Stepanoff

Edvocia

Turzo

required point

. .

4421.053 539.741

4736.842 444.687

5052.632 342.022

5368.421 231.8035684.211 114.009

6000.000 -11.508

1000

(feet)

0

500

0 2000 4000 6000 8000

Q (RB/day)


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ESPCPs performances operating viscous oil


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Rod driven PCPs performances operating viscous oil


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Comparison between ESP and ESPCP

( = 336 cp)

ESP ESPCP

BHP required : 119.8 BHP required : 23.0

Efficiency : 15.9% Efficiency : 68.5%


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Conclusions

9 Both ESPs and PCPs are suitable to handle highviscous oils

9 PCPs are uite insensitive to oil viscosit showinno reduction in head, capacity.

9ESPs do loose head, capacity and efficiencyperformances requiring heavy oversizing.

However this low efficiency ends up in heatingthe produced oil hence reducing its viscosity.


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Future developments for ESPs in viscous oils


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Future technologies to operate viscous oil

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