Progressing Cavity Pumps forAggressive Oil Applications2010 SPE ATW Cancun

Presented by: Oscar Salazar

1

Outline

• Introduction

• Aggressive oil applications (aoa)

• Problems in (aoa)

• Materials engineering approach

• Experimental

• Field trials

2

PC pump Key Attributes

• low CAPEX / OPEX

• handle liquids, solids and gases

• high overall system efficiency

• low profile, low noise

3

Aggressive Oil?

• light oil, above 35 API, often warmer• medium oils with aromatics• coal bed methane with CO2 gas.• light aromatics (benzene, xylene, toluene)• sour: CO2 + H2S• corrosion inhibitors, amines• chemical stimulation fluids

Severity depends on level ofcombinations

4

What Problems in AOA?

• elastomer swell (liquid or gas)– high torque– reduced cavity volume– severe damage surfacing

• elastomer/metal degradation– excessive hardening or softening– bond deterioration– corrosion (rotors, tube)

Low pump reliability

5

Why Problems in AOA?

• elastomer swelling caused by– physical contact with fluids

– explosive decompression (CO2,H2S, N2, CH4)

• degradation caused by– elastomer/metal chemical reaction

• amines, corrosion inhibitors

• water (Hydrolysis, salts, PH)

• O2 (thermal degradation)

• H2S

6

Swelling by fluids

A physical phenomenon governed by– polymer-solvent solubility

– temperature

– solvent viscosity and shape

– activity of multicomponent fluids

– elastomer thickness

– elastomer composition

7

Effect of water on elastomers• high water cut oil (> 90%), dilution effect

• wide range of swelling in PC pump

• elastomer selection is critical

Designation Vol swell (%)Elastomer A 12.28Elastomer B 4.00Elastomer C 0.50Elastomer D 15.63Elastomer E 19.50Elastomer F 26.77Elastomer G 16.48

Swell in water at 100o C, 7 days

8

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

0 2 4 6 8 10 12 14 16 18

Time (day)

Mas

s C

han

ge(

%)

Top LayerSecond LayerMiddle Layer

Swelling: Effect of thickness

Medium nitrile swell in 30/70 Isooctane/toluene at RT, 3 days

6.1%

0.8%

0.8%

0.8%6.1%

12 mm

Top layer

second layer

Middle layer

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Explosive Decompression (ED)• Failure shows blisters or cracks within elastomer

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ED mechanism

• gas dissolves and diffuses into elastomer

• high pressure, absorbed gas at equilibrium• pressure releases, gas comes out of solution• pressure differential: gas expansion - swelling

• at critical elastomer internal pressure: bubbles orcracks are inevitable

• internal pressure depends on elastomercomposition

11

ED variables

• a complex phenomena, too many variables

– temperature

– gas/fluid mixture

– differential pressure magnitude

– time of exposure

– depressurization rate, dwell time

– depressurization cycles

– thickness, geometry, constraints

– elastomer composition

12

Historical Application….

• fluid analysis + compatibility testing (sometimes)

• select best elastomers

• rotor sizing to accommodate swell (trial and error)

• sizing iterations based on performance

13

Materials Engineering …

• elastomer composition vs. critical properties

• DOE

• lab mixing and testing

• manufacturing trials

• full scale product testing

• field testing

• commercialization

14

Materials Engineering….

• a tool for design

• balanced properties

• compatibility tests

• predictive rotor sizing

• materials “fit for service”

New approach for aggressive oil

15

Elastomer Development Example

• tests under lab conditions

• tests under aggressive crude oils and chemicals

• explosive decompression tests

• comparison with other elastomers

• field trials

A fit for purpose elastomer

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RESULTS

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Swelling vs. aromatic content3 day test, 50o C in Isooctane / Toluene blends

0.00

5.00

10.00

15.00

20.00

25.00

30.00

0% 5% 10% 15% 20% 25% 30% 35%

%Toluene

%Vo

l

Elastomer CElastomer AElastomer B

Newdevelopment

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Volume swelling aggressive fluids

rotating autoclaves, 7 days, ASTM D412

A B C A B C1 Colombia 15% 21 ND 48 1500 8.1 2.7 NT -21.0 -6.0 -3.02 Romania 90% 30-40 ND 50 2200 6.3 1.3 NT -11.0 -2.0 NT3 Africa 30% 22 3% 60 1500 16.5 7.4 21.7 -21.0 -6.0 -3.04 Czech Republic 50% 32.5 ND 50 1500 5.6 0.9 NT -9.0 -2.0 NT5 Canada 38% 36 9% 48 1100 4.8 2.2 9.8 -8.0 2.0 -13.0

No

Hardness change(pts)Location BHT

DegCBHP(psi)

% Volume swellWatercut API Aromatics

(%mol)

A: elastomer A, std nitrileB: elastomer B, new developmentC: elastomer C, std nitrile

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Volumetric swelling in chemicalscorrosion inhibitor; alkylamine salt; 65o C; 1,000psi

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

0 10 20 30 40Time (hours)

%Vo

l.

Elastomer A

Elastomer B

Newdevelopment

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Explosive decompression tests

Mixture of gas 90%CH4 and 10% CO2

Elastomer A Elastomer B

Soaktime

(days)Pressure

(Psi)Depres rate

( psi/min)Temp

©

VolumeChange

Hardnesschange

AverageCrackLength

Elastomer A 3 1900 240 70 20.93 -1 4.3Elastomer B 3 1900 240 70 7.35 -3 4.4

Formulation ED Testing Details according to Norsok M-CR-710 guideline

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Swelling by elastomer family

Viton HNBR A Elastomer B HNBR B1.63 24.22 1.94 7.090.63 15.40 0.34 3.48-1 -15 0 -4Hardness Change (Shore A)

Clear FracVolume Change (%)Mass Change (%)

3 day test, 100o C, 1,000 psi

• Clear Frac characteristics:– API: 41.8– aromatic content: 3.2%

22

Field trials: Huila- Colombia• Problem

– reduced life: less than 6 months.– high torque (seized rotors) after shut down– ED presence

• operational conditions– API gravity: 21, water cut 15%– CO2: not determined– GOR: above 200 scf/bbl– BHT: 48o C, BHP: 1500 psi.

• change to elastomer B, Model: 22-1500

23

Field trials: Huila- Colombia• increased run from 180 days to 488 days

• ED problems minimized

Elastomer A: 6 months Elastomer B: 15 months

24

Pengrowth Enchant - Canada• problem:

– Inability to restart after shutdown

– Rotor resizing several times a year (money $$$$)

• operational conditions:– API gravity: 26.2, water cut 98%

– CO2: 22% molar, H2S: 0.7%

– GOR: 200 m3/m3 BHT: 30o C BHP: 100 psi.

• change to elastomer B

• pump model: 47-1500

25

Pengrowth Enchant- Canada

• 1st pump: 9 1/2months– no torque problems– pump showed subsurface cracking at surface.

• 2 more pumps with 360+ days run and no rotorchange

Discharge

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Summary

• PC pump elastomer limiting factor in AOA

• swelling and ED are the main problem

• elastomer can be engineered for AOA

• “fit for purpose” elastomer:

– simplify pump application process

– improves performance

– expands application range

27

Questions????