Chemical Foamers For Gas Well Deliquification Training ... · Chemical Foamers For Gas Well Deliquification Training Workshop Presented by: ... Corrosion inhibitors ... Capstring

Confidential 1

Chemical Foamers For Gas Well Deliquification

Training Workshop

Presented by: Duy Nguyen

Martin J Willis

European Gas Well Deliquification Conference

Groningen, Netherlands, Sept 2009

Essential Expertise for Water, Energy and AirSM

Workshop Contents

�Theory of Foam

�Foamer Chemicals

�Laboratory Testing

�Application in the Field

�Summary

Confidential 2

Basic Foam Theory

� Physics of foam

� in “close-up”

� at a molecular level

� How foam is stabilised

� Role of surfactants

Foam

�Why is High Foam Desirable ?

� Seen as evidence product is working

� ie. Shampoo, dishwashing liquid

� Indicates where product has been applied

� ie. Shaving foams, abattoir cleaners

� High expansion ratio

� Fire fighting foams

� Reduced liquid density and reduced surface tension

� i.e, gas well deliquification

Confidential 3

Soap – We Use It Everyday!

�Daily used surfactant

�Definition:

�Foam is a dispersion of gas in liquid and is caused by agitation and surfactant

Images courtesy of “google images”

Foamer Chemicals

� Surfactants typically applied to aqueous systems

� Reduce surface tension

� Decrease relative density

� Increases elasticity

� Allows gas/liquid dispersion at a lower gas pressure.

� In the lamellar condensate is trapped

� The benefits

� Reduces the critical velocity of the well

� Enables liquid unloading with low set-up cost

� Customised for local environment

� Facilitates continuous production

� Reduces well decline curve

LIQU

ID

GA

S

GA

S

Confidential 4

Dynamic Surface Tension Apparatus

2)( max rPP

o−

=γ

Dynamic Surface Tension Data

10.2% NaCl and 3.7% CaCl2.2H2O

20.00

25.00

30.00

35.00

40.00

45.00

50.00

55.00

10 100 1000 10000 100000Time (milliseconds)

Su

rfa

ce

Te

ns

ion

(m

N/m

)

Betaine at 400 ppm

Alkyl Ether Sulfate at 400 ppm

Olefin sulfonate at 400 ppm

Confidential 5

Correlation Between Max DST Reduction Rate & % Liquid Unloading

R2 = 0.95

40

45

50

55

60

65

70

75

80

400 500 600 700 800 900 1000

DST Reduction Rate, dyne/cm.s

% U

nlo

ad

ing

Olefin sulfonate

Alkyl ether

sulfate

Betaine

Conditions: 400 ppm active surfactant in 10.2% NaCl and 3.7% CaCl2.2H2O, 0% condensate

Foam Life Cycle

� Gas forms spheres in

liquid.

� Honeycomb with thick

lamellae between cells.

� Liquid drains into

junctions leaving thin

lamellae between cells.

Surfactant Properties - Foam

Formation

Confidential 6

Pure Liquids Don’t Foam

Gas

Gas

Liquid

Gas

Gas

Liquid

Gas

Liquid

. . .

When the Bubbles Collide .....When the Bubbles Collide .....

Film stabilisation

Foam drainage

.... .... they “unload” waterthey “unload” water

Confidential 7

Low Gas VolumeLow Gas Volume

Foam

Drainage

High Gas VolumeHigh Gas Volume

Polyhederschaum

Two Types of Foam

Foam Drainage Leads to Collapse

Caused by

Plateau

Border

Lamella

PolyhederschaumKugelschaum

� Gravitational force

� Capillary pressure

� Diffusion of gas

� Bursting of bubbles

� Rearrangement of lamellae

drainage

Confidential 8

Gas Permeability & Bubble Growth

Gas

Gas

Liquidr1

r2

. . . Also leads to foam collapse

Film Elasticity .......

...... makes them stretchy!...... makes them stretchy!

Confidential 9

FOAM STABILIZATIONFOAM STABILIZATIONFOAM STABILIZATION

PLATEAU BORDER FORMED FROM INTERSECTION OF 3 OR MORE FOAM CELLS

PLATEAU BORDER FORMED FROM INTERSECTION OF 3 OR MORE FOAM CELLS

SURFACTANT STABILIZATION OF FOAM LAMELLAE

SURFACTANT STABILIZATION OF FOAM LAMELLAE

Liquid flows

Liquid flows

Liquid flows

Marangoni Effect

-

-

-

-

- -- -

- -

- -- -- -

Viscous drag

Liquid flow

Viscous drag

Liquid flow

Surface tensionrestoring force

��

--

-

-

-

-

-

Micellarreservoir

Drainage -

The dynamics of rapid diffusion needed to restore and maintain film elasticity . . .

Confidential 10

Foam Stability: Area per molecule

Packing at the air-liquid interface

Air Air

Liquid Liquid

• Unstable foam

Loosely packed film Tightly packed film

- High area per molecule - Small area per molecule

- Low degree of packing - High degree of packing

• Stable foam

Area

FOAMFOAM

ElasticityElasticity Degree of packingDegree of packing

Confidential 11

Foam

�Foam stabilisation is thought to occur via the following mechanisms:

� Increasing elasticity of the foam film

�Slowing drainage of liquid in the lamellae

�Decreasing the diffusion of gas across the lamellae

� Increasing the thickness of the electrical double layer

� Increasing the surface and bulk viscosity of the foam film

Foam Inhibition

�Disruption of interfacial film structure

�Displacement of stabilising surfactant

�Poor interfacial orientation

�Spontaneous spreading of oils

�Low surface tension liquids

�Positive spreading coefficient

�Physical rupture of lamellae

�Waxy or hydrophobic particles

�Oil droplets and inverse micelles

Confidential 12

Configuration of Oil at the Air-liquid Interface

Oil Water

Air

Oil drop inside the solution

Oil

Pseudoemulsion Film

Oil drop at the surface separated by a pseudo-

emulsion film from the air

Oil

Oil drop enters the gas phase and forms lensOil spreads at the solution surface

and ruptures the bubble

Mechanisms of Foam Break Degradation

� Coalescence

� The flocculated foam cells form larger bubbles due to thinning and

rupture of the lamellae separating the bubbles. Usually occurs as a result of thinning due to prolonged drainage

� Gravitational separation

� Rise of bubbles through foam mass, while liquid is draining due to gravity through lamellae and plateau borders between bubbles

� Disproportionation

� The gas inside the bubbles diffuses across the foam lamellae, from areas of high pressure - small bubbles to areas of lower pressure -large bubbles

Confidential 13

Foam

�What does a foam modifier/booster do ?

�Product that acts synergistically with another product to increase volume of foam

�Product that stabilises the foam to prevent breakdown of the foam structure

� Improves appearance of a foam

� i.e. creamier appearance

Foam

�Additives for foam stabilisation

�Organic compounds

� Polymers

� Surface active materials

� Biopolymers

�Electrolytes

�Finely divided particles

Confidential 14

Foam

�Effect of addition of foam stabiliser

� Increases packing density at air/water interface

�Cause charge shielding of charged surfactant

�May interact with charged surfactant

�May reduce the CMC

Foam

�Commonly used foam stabilisers

�Fatty alcohols

�Amine oxides

�Betaines

�Alkanolamides

Confidential 15

Typical Chemicals

� Nonionic � More soluble at lower temperature

� Increase temperature &/or salt concentration reduces solubility – lowers cloud point

� Good for wells with unknown water chemistry

� Anionic� Excellent aqueous foamers

� Highly polar

� Can be affected by high brine solutions

� At elevated temperatures can degrade

� Cationic � Good for foaming water/oil mixtures

� Efficacy dependant on molecular weight

� Can be prone to emulsion issues

� Amphotheric� Very versatile

� Good high temperature performance and stability

� Effective in high salt content brines

R

SO3Na

α-olef in sulfonate

R

O

SO4Nan

Alkyl ether sulfate

R

SO3Na


R

SO3Na


R

O

SO4Nan

Alkyl ether sulfate

R

O

SO4Nan

Alkyl ether sulfate

R NH

NO Na

OCH3

CH3 O

-+

Cocoamidopropyl betaine

R NH

NO Na

OCH3

CH3 O

-+

Cocoamidopropyl betaine

Combination Products

�Formulating additional actives into foamers

�Corrosion inhibitors

�Scale inhibitors

�Biocides

�Paraffin inhibitors

�etc

�Facilitates easier chemical programs

�Less inventory

�Reduce exposure risks

�Saves on pumps, storage and freight

Confidential 16

Foam

�Selection of surface active foam stabiliser

�Type of foam to be stabilised

� Charged

� Nonionic

�Structure of surfactant hydrophobe

� Alkyl chain length

� Branching on alkyl chain

�Presence of polar entities capable of forming multiple hydrogen bonds

�Ability to lower the CMC

Foamer Chemical Requirements for Gas Well Deliquification

� Provide foam stability to carry liquids to surface

� Thermal stability

� Fluid compatibility (chloride, solids,..)

� Ability to unload hydrocarbon

� Break at surface before entering surface equipment

� Delivery (batch, continuous)

� Winterized

Confidential 17

Chemical Solutions

�Solid state� Dropped downhole to find aqueous environment

� Dissolve in the liquid

� Foam when liquid and gas mix

�Liquid Foamers� Delivered by various means at targeted locations

� Already in liquid state, so require less soak time

� Foam when liquid and gas mix

Foaming Technology

Yesterday, foamer selection was a lot like fishing. It was

an art.

Yesterday Today Tomorrow

Investigation of key factors that govern the foaming performance and foaming

mechanisms.*To be published in “Petroleum Science and Technology”

Journal

Modeling and prediction of foamer performance: a

proactive approach

Confidential 18

Factors That Influence Foaming

A 25 Factorial Design ( a 2 level with 5 factors) with two replicates (64 experiments)

Performance Response: % Unloading

Temperature 25oC 70oCOil 0 % 50% Chloride 2.4% 8%Foamer dosage 400ppm 1000 ppmOil type cycloalkane aliphatic

Factors Levels

Temperature 25oC 70oCOil 0 % 50% Chloride 2.4% 8%Foamer dosage 400ppm 1000 ppmOil type cycloalkane aliphatic

Factors Levels

Design Of Experiment

FOAM

FOAM

TemperatureTemperature ChlorideChloride % Oil% Oil

Confidential 19

Design Of Experiment

FOAM

FOAM

Foamer DosageFoamer Dosage Oil TypeOil Type

Cycloalkane

Aliphatic

FOAM

FOAM

Prediction of Foamer Performance

Predicted vs. Actual % Unloading

2222

Actual

Predicted

-11.08

14.33

39.75

65.16

90.58

-11.08 14.33 39.75 65.16 90.58

R2 = 0.917

Confidential 20

Conclusions

�Prediction and modeling of foamer performance with confidence

�A proactive approach to manage program

�“No touch” foaming testing

�Quick response when process variables change

�Foamer mapping

Laboratory Testing

Confidential 21

Laboratory Testing

� Standard Laboratory Testing

� Standard performance tests� ASTM D-3601 - Foam in Aqueous media (Bottle Test)

� ASTM D-3519 - Foam in Aqueous media (Blender Test)

� ASTM D-892 - Column/Cylinder Test Method (Dynamic Test)

� Specialised performance test

� Unloading rig

� Injection systems

� Well simulators

� Customer tests

� Example Protocol

Standard Chemical Testing

Product

Recommendation

Density

Ecotox Environmental

Profile

Flash Point

Thermal Stability

Materials Compatibility

Viscosity Profiles

Emulsification Tendency

Defoamer Compatibility

Chemical Compatibility

Product

Recommendation

Product

Recommendation

Density


Profile

Flash Point

Thermal Stability



Viscosity ProfilesViscosity Profiles





Confidential 22

ASTM D-3601 (Foam in Aqueous media -Bottle Test)

� Quick and cheap test

� Established for aqueous, low viscosity system

� Using low shear to generate foam

� Some foamers are prone to perform better under shear rather thangas flow

� If high shear required use the blender test

� Result is a comparison of foam height and nature versus a control

ASTM D-3519 (Foam in Aqueous Media - Blender Test)

� Data Collected

� Foam Height

� Foam Life

� Drainage Half Life

� Foam characterization under high shear conditions

� Hydrocarbon influences difficult to assess due to affect on foam height and emulsification issues

� Some surfactants prone to generate more foam in high shear conditions

Confidential 23

ASTM D-892 & Modifications(Column/Cylinder Test Method – Dynamic Test)

� Data Collected

� Foam height versus Time

� Fluid carry over with given gas rate (0.01–10 ft/sec)

� Foam life

� Drainage half life

� Modifications

� Heating the liquid to provide more representative conditions

� Changes the size of the cylinder – gives different ID

� Still assess the same properties

Dynamic Unloading Rig

% Unloading vs Time

400 ppm active foamer and 75% Condensate

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Time, min

% U

nlo

ad

ing

Novel Nalco Foamer (patent pending)

Traditional Foamer

timeFoam >1000ml

% Unloading vs Time


0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Time, min

% U

nlo

ad

ing


Traditional Foamer

% Unloading vs Time


0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Time, min

% U

nlo

ad

ing


Traditional Foamer

% Unloading vs Time


0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Time, min

% U

nlo

ad

ing

Time, min

% U

nlo

ad

ing


Traditional Foamer


Traditional Foamer

timeFoam >1000ml

100W

W Unloading%

initial

min 15tX

==

αααα-olefin sulfonate Betaine

High condensate

foamer

Carry over

arm

Gas In

Jacketed

cylinder

Foam Stability

Confidential 24

Capstring Injection Performance

�Capstring simulation

�Fitted with atomising nozzle at base of column

�Same principal and output as the unloading rig

Atomiser Performance

Confidential 25

Automated High Pressure & Temperature Foam Column Testing Apparatus

Pakulski M.“AUTOMATED HIGH PRESSURE, HIGH TEMPERATURE FOAM COLUMN TESTING APPARATUS”, Gas Well Deliquification Workshop, Denver, Colorado February 23 -26, 2009

� Lab simulator to make closer comparison to the field

� Temperature

� Pressure

Operator Test ProtocolProcedure for testing foamer performance

200 milliliter tap water (or produced water from a well, or artificial brine based on well water

analyses) is transferred into a 1000ml measuring cylinder (h = +/- 450mm. ∅ = 60mm,) 40ml white spirit, and foamer is added (1000- 5000ppm.) A nitrogen sparge (50l/hr) is applied to the cylinder via a P2 sintered gas dispersion tube. The height reached in the column after 2 minutes bubbling is noted, or the time taken to fill the column up to the 1000ml mark (1.) The gas sparge is removed and for those samples that reached the 1000ml mark and the time taken to collapse to half of the foam column level (+/- 600ml) is noted together with the time taken for the foam to collapse completely. At this stage, any observations regarding the mixture quality are noted (emulsions, solids, water quality, condensate quality.) The nature of the foam is noted. The following observations are noted:

- Foam build up time (s) - Half-life of foam column (or >240 s) - Foam type - Other observations

Foam build-up time

Foam build-up time

Foam build-up time

< 80 s good

80 < x < 120 moderate

> 120 poor

Foam half-life time Foam half-life time

Foam half-life time

< 240 good

60 < x < 240 moderate

< 60 s poor

Confidential 26

Taking Technology To The Field

Chemical Methods of Artificial Lift

� Soapsticks

� Batch treatments

� Squeeze treatments

� Continuous applications

�Chemical drip

�Capillary injection

� Combination products

Confidential 27

Pros & Cons of Chemical Methods

� Pros

� Set-up and operating cost

� Potential to use to abandonment

� Versatility for different completions and environments

� Can be used in addition to mechanical methods

� Tolerance of particulates

� Rapid response

� Automated continuous programs

� Can controls down hole corrosion, scale and paraffin problems

� Cons

� Placement can be difficult

� Soapsticks

� Capstrings

� Need to monitor stock

� Personnel intervention

�Well conditions change could render specific product ineffective

� Temperature stability on surface and down hole

� Environmental concerns

Well Suitability & Modelling- From The Lab To The Field

Confidential 28

Production Patterns

�Sharp decline in production rate

�Changes in water production

�Slugs of liquid coming through

�Decline in produced water &/or condensate

�Changes in pressure deltas

�Casing minus tubing versus time

Critical Velocity Model

INPUT DATA: PREDICTION OF LIQUID LOADING

Tubing I.D., inches 2.441 Desensitized Model - WATER ONLY

Wellhead Temperature, oF 85 vt, ft/sec 9.46

Wellhead Pressure, psig 500 Qg, Mscf/d 967

Gas Specific Gravity 0.68 vt, ft/sec (w/ Turner Adj. Factor of 20%) 11.35

Mole Fraction N2 0.002 Qg, Mscf/d (w/ Turner Adj. Factor of 20%) 1,161

Mole Fraction CO2 0.023

Mole Fraction H2S 0 Desensitized Model - CONDENSATE ONLY

Condensate Rate, bbls/d 57.4867 vt, ft/sec 6.08

Condensate API Gravity 55 Qg, Mscf/d 623

Water Rate, bbls/d 56.2397 vt, ft/sec (w/ Turner Adj. Factor of 20%) 7.30

Sodium - Na 17,000 Qg, Mscf/d (w/ Turner Adj. Factor of 20%) 747

Calcium - Ca 250

Potassium, - K 150 Desensitized Model - WATER & CONDENSATE

Magnesium - Mg 10 vt, ft/sec 8.00

Strontium - Sr 5 Qg, Mscf/d 818

Barium - Ba 3 vt, ft/sec (w/ Turner Adj. Factor of 20%) 9.60

Iron - Fe 12 Qg, Mscf/d (w/ Turner Adj. Factor of 20%) 982

Chloride - Cl 55,000

Sulfate - SO4 75 Desensitized Model - WATER & FOAM

Bicarbonate - HCO3 25 vt, ft/sec 6.426

Qg, Mscf/d 657

Confidential 29

Modeling Process, Output & Ranking

Variable Results Completion Details Is a completion diagram available?

Tubing I.D., inches Well depth (VD and TVD)

Casing I.D. inches Perforation depth and spacing

Wellhead Temperature, °F Well deviation

Wellhead Pressure, psig Is the well completed with a packer?

Botton Hole Temperature (degF) If yes, what depth is this at

Bottom Hole Pressure (psig) If not, is there access to the annulus?

Gas Specific Gravity Is there an injection string or plans to install one?

Mole Fraction N2 Are there any specific materials compatibilities?

Mole Fraction CO2

Is the tubing clean and free of deposits? Surfactants can remove

deposits & it is important to understand the fate of these & potential

impact on the process

Mole Fraction H2S Is a liquid level known?

Condensate Rate, bbls/d Treatment

Condensate API GravityIs a chemical storage tank, sight glass and injection pump available for

the application?

Water Rate, bbls/dDoes the operator have a company internal calculation to base the

economics of the foaming option?

Current gas rates (mmscfd) Surface Implications

What is the production pattern;

continuous, intermittent, shut in?Is there an injection point at the wellhead for the application of antifoam?

Sodium - Na What is the distance to the separation trains?

Calcium - Ca Do the level controllers in the inlet separator operate smoothly?

Potassium, - K Are there any water quality specs?

Magnesium - Mg Is water disposed overboard, storage tank, re-injected?

Strontium - Sr Is there a downstream compressor?

Barium - Ba

Iron - Fe

Chloride - ClSulfate - SO4

Bicarbonate - HCO3

INPUT DATA:

Brine

Chemistry /

ppm

INPUT DATA:

Variable A B C D E

Tubing I.D., inches 5.5 4.767 4.892 4.767 4.767

Casing I.D. inches 6.184 4.897 6.189 2.867 3.795

Wellhead Temperature, °F 72 60 68 55 60

Wellhead Pressure, psig 198 204 165 176 205

Botton Hole Temperature, °F 146 141 155 165 143

Bottom Hole Pressure, psig 1025 55 572 595 900

Gas Specific Gravity 0.59 0.59 0.59 0.59 0.59

Mole Fraction N2 0.011 0.011 0.011 0.011

Mole Fraction CO2 0.002 0.002 0.003 0.002

Mole Fraction H2S 0 0 0 0 0

Condensate Rate, bbls/d 1 2 1 1 1

Condensate API Gravity 56 56 56 56 56

Water Rate, bbls/d 4 33 2 9 1

Sodium - Na 65910 65910 64770 65910

Calcium - Ca 13560 13560 19830 13560

Potassium, - K 1468 1468 1805 1468

Magnesium - Mg 2523 2523 4138 2523

Strontium - Sr 420 420 1035 420

Barium - Ba 2 2 6 2

Iron - Fe 161 161 265 161

Chloride - Cl 136000 136000 20000 139200 136000

Sulfate - SO4 425 425 255 425

Bicarbonate - HCO3 35 35 10 35

Current gas rate mmscf/d 2.8 3 1.75 0 2.2

Well depth (TD and TVD) TD 10700 ft 99551ft TD 11065 ft TD 12557 ft TD

Packer depth 8311 ft 7276 ft 7819 ft 7756 ft 10412 ft

Perforation depth and spacing

A 10075 - 10212

B 10228 - 10284

C 10310 - 10354

D 10378 - 10440

8220 - 9785 ft

A 9045 - 9145

B 9178 - 9270

C 9285 - 9331

10939 ft

A 11387 - 11610

B 11660 - 11720

Brine

Chemistry

Well

Tubing A B C D E

ID / in 5.5 4.767 4.892 4.767 4.767

Crit

ical

rate

s

Water only 3,478 2,679 2,440 2,501 1,698

condensate only 2,183 1,675 1,581 1,561 1,061

water/condensate 3,092 2,447 2,164 2,263 1,391

water / foam 2,373 1,819 1,662 1,698 1,153

max. production rate / mscf/d 2,800 3,000 1,750 0 2,200

% above water critical -19 12 -28 -100 30

Total daily liquids (est.) 5 36 2 10 2

Casing A B C D E

ID / in 6.184 4.897 6.189 2.867 3.795

Crit

ical

rate

s

Crit

ical

rate

s

Water only 4,396 2,827 3,905 4,294 2,679

condensate only 2,760 1,767 2,530 2,681 1,675

water/condensate 3,909 2,582 3,464 3,881 2,195

water / foam 2,999 1,920 2,661 2,917 1,819

max. production rate / mscf/d 2,800 3,000 1,750 0 2,200

% above water critical -36 6 -55 -100 -18

Total daily liquids (est.) 5 36 2 10 2

Crit

ical

rate

s

Ranking

Hard decline

Production Trend

Bes

t Tria

l

Can

dida

te

Comment

Model shows loading in both the tubing and casing of this well. Liquid production is low, so this could

indicate DH liquid accumulation. A

C

ESteady decline, intermittent

rates > critical

Decline since year start

Hard decline

Model shows both the well tubing and casing are not far from critical conditions. Application of foamer

now could delay the onset of liquid loading and maintain continuous production.

Rise at year start, but now

decline

Bes

t Tria

l

Can

dida

teModel shows loading in both the tubing and casing of this well. Liquid production is low, so this could

indicate DH liquid accumulation.

Evidence to infer loading in both the well's tubing and casing. Liquid production is low, so this could

indicate liquid build up DH. Supported by production rate decline

Leas

t Suite

d

Model shows well to be producing above the tubing critical rate, but below critical in the larger ID

casing. Flow regime and liquid production would indicate this as a candidate for treatment.

B

D

Model shows both the well tubing and casing are not far from critical conditions. Application of foamer

now could delay the onset of liquid loading and maintain continuous production.

Production for this well is intermittent, but it would appear levels are already < critical for water and

foam combined. Possible batch candidate, although it may be beyond help from foamer

Rise to mid-year then

decline

Rise at year start, but now

decline

Leas

t Suite

d

Echometer

� A tool for finding the liquid level

� Can assist in treatment planning and suitability assessment

� Widely used in the industry

Confidential 30

Lab Testing & Product Selection

Product

Recommendation

Foamer Performance

Density


Profile

Flash Point

Thermal Stability


Viscosity Profiles




Field Application

� Treatment options

� Topside trial

� Batch

� Liquid batch

� Solid state

� Squeeze

� Continuous

� Drip

� Capillary string

� Well & process considerations

� Climate

� Supply / logistics

� Well completion

� Hardware limitations

� Easy to control treatment and optimise rate

� Rapid response to dosing

Confidential 31

Monitoring Performance

� Foamers will respond quickly in a system

� Beneficial for trials and optimisation

� KPIs

� Production rates� Gas, Liquids (water / condensate)

� Flowing time

� Shut-in period

�Wellhead temperature

� Other important parameters� Separation efficiency

� Oil in Water levels

� These are often dictated by the well and process set-up

� E.g. if there is no test separator then accurate monitoring of production rates can be difficult

Batch Treatment

�This can be applied in a various ways�Solid state soapsticks

� Manual or automated drop via production tubing

�Batching down the backside

� Only on packerless completions

�Batch and Fall

� Good if the well can be rocked

� If there is a very high level of loading

�Bull heading or tubing displacement

� Use a volume of flush to drive the chemical into location

�Squeeze

� Can be achieved with liquid or gas and the post-treatment flush

Confidential 32

Offshore Application

� Condensate loaded well (>95%)� 30,000 ppm foamer batched via production tubing

� Well shut-in for 24 hours

� Initial flow back, well failed to kick

� Shut-in for additional hour

� Production kicked with significant benefits

Down hole Batch Treatment

Variable

Previous

Flow

back

Trial

results % gain

Condensate within 30 mins/bbls 5 40 700

Gas Rate after 30mins/mmscfd 5 6.5 30

Condensate after 12 hours 50 81 62

Well uptime (days) 6 60 900

Offshore Application

�Trial Conclusions

�Batch treatments completed on a condensate dominant well

� Levels at >90% condensate

�Key differentiators observed by Operator

� Superior modelling of candidate wells

� Unrivaled performance in lab tests

� Knowledge and contribution of foamer expertise

� Minimal effect on PW quality

� Environmentally “green”, non-sub product, gold HQ

�Production benefits observed in many ways

� Key advantage being well shut in cycling went from every 6-8 days to 63 day interval

� No impact on BS&W or OiW

Confidential 33

Squeeze Application

Zinterl M. “Foamer Squeeze - The

Advancement of Foamer Batching”,

Gas Well Deliquification Workshop,

Denver, Colorado February 23 -26,

2009

Continuous Treatment

� Continuous injection is preferred

� Capillary strings are most efficient means

� Can occur via the gas lift system

� Depending on completion strings can be run down the producer (concentric) or banded on the tubing (eccentric)

� Various types of atomisers and nozzles available

� Placement is key to performance� Need to ensure that the chemical is delivered to the

correct location

� Typically aim for top perforations

� Can be used in addition to other artificial lift methods

Co

nfid

en

tial

34

Capstrin

g Treatm

ent

Date

Production rate / MSCF

Walk

er K

2

0.0

100

.0

200

.0

300

.0

400

.0

500

.0

600

.0

700

.0

2/21/05

4/21/05

6/21/05

8/21/05

10/21/05

12/21/05

2/21/06

4/21/06

6/21/06

8/21/06

10/21/06

12/21/06

Pro

du

ctio

n

Fo

am

er B

atc

h T

rend

Date


Date


Walk

er K

2

0.0

100

.0

200

.0

300

.0

400

.0

500

.0

600

.0

700

.0

2/21/05

4/21/05

6/21/05

8/21/05

10/21/05

12/21/05

2/21/06

4/21/06

6/21/06

8/21/06

10/21/06

12/21/06

Pro

du

ctio

n

Fo

am

er B

atc

h T

rend

Walk

er K

2

0.0

100

.0

200

.0

300

.0

400

.0

500

.0

600

.0

700

.0

2/21/05

4/21/05

6/21/05

8/21/05

10/21/05

12/21/05

2/21/06

4/21/06

6/21/06

8/21/06

10/21/06

12/21/06

Pro

du

ctio

n

Fo

am

er B

atc

h T

rend

Batch Vs Contin

uous Applicatio

n

>2

40

00

MS

CF

Confidential 35

Continuous Application Using Atomiser

Well #3, 35% CondensateWell #2, 24% Condensate

Onshore Application Batch & Continuous

� Batch and Continuous trials completed versus incumbent product

� Performance comparable or better

� Batch

� Equivalent performance at reduce treat volume

� Continuous

� First trial well neither product improved production

� Second application Product A gave excellent performance

� improvement over Incumbent

Timeline Product Treat Rate Ave. Production Rate

l / hr Mm3 / day

15 215

+1 hr 5 185

+15 hr 5 185

5 130

+7 hr 5 130

System flush and change out of product

Product A

Incumbent

WAV15-FR-4-17-1

NM3/D

WAV15-PT-4-17-2

barg

Plot-0

01/09/2008 13:49:29.828 01/10/2008 13:49:29.82830.00 days

10000

20000

30000

40000

50000

60000

70000

0

80000

0

70

57.686

1.2506E-12

Incu

mben

t: 5

0li

tres

Incu

mben

t: 1

00

litr

es

Pro

du

ct A

: 7

5li

tres

Pro

du

ct A

: 7

5li

tres

Pro

du

ct A

: 50 l

itre

s

Co

nfid

en

tial

36

Applicatio

n Above Critic

al Velocity

Date


0.0

20

0.0

40

0.0

60

0.0

80

0.0

100

0.0

120

0.0

140

0.0

160

0.0

3/4/05

3/11/05

3/18/05

3/25/05

4/1/05

4/8/05

4/15/05

4/22/05

4/29/05

5/6/05

5/13/05

5/20/05

5/27/05

6/3/05

6/10/05

6/17/05

6/24/05

7/1/05

Prod

uctio

n

Pre-F

oam

er T

rend

Tubin

g C

ritical V

elo

city

Ad

ded F

oam

er 5

-04-0

5

Date


Date


0.0

20

0.0

40

0.0

60

0.0

80

0.0

100

0.0

120

0.0

140

0.0

160

0.0

3/4/05

3/11/05

3/18/05

3/25/05

4/1/05

4/8/05

4/15/05

4/22/05

4/29/05

5/6/05

5/13/05

5/20/05

5/27/05

6/3/05

6/10/05

6/17/05

6/24/05

7/1/05

Prod

uctio

n

Pre-F

oam

er T

rend

Tubin

g C

ritical V

elo

city

Ad

ded F

oam

er 5

-04-0

5

Applicatio

n of C

hemical w

ith Plunger

Date


0.0

100.0

200.0

300.0

400.0

500.0

600.0

7/18/06

8/1/06

8/15/06

8/29/06

9/12/06

9/26/06

10/10/06

10/24/06

11/7/06

11/21/06

Production

Foam

er

PlungerFoam

er and Plunger

Date


Date


0.0

100.0

200.0

300.0

400.0

500.0

600.0

7/18/06

8/1/06

8/15/06

8/29/06

9/12/06

9/26/06

10/10/06

10/24/06

11/7/06

11/21/06

Production

Foam

er

PlungerFoam

er and Plunger

Confidential 37

Application of Combination ProductsWell A

Production

Gas Mscf/d 450

Water / BOWPD 12

Condensate / BOPD 0

Tubing Pressure / Psi 400

Casing Pressure / Psi 400

Treatment

Date Chemical

13/09/2007 Batch CI

23/11/2007 Foamer batch



07/02/2008Installed continuous

backside treatment

Corrosion Data

Pitting Rate / MPY 1.4 - 5.3

General Rate / MPY 2.4 - 7.3

Caliper Surveys 03/12/2007

06/06/2008

Well B

Production

Gas Mscf/d 330

Water / BOWPD 14

Condensate / BOPD 0

Tubing Pressure / Psi 400

Casing Pressure / Psi 800

Treatment

Date Chemical

26/09/2007 Batch CI

21/11/2007Installed continuous

backside treatment

Corrosion Data

Pitting Rate / MPY 4.5 - 12.2

General Rate / MPY 0.6 - 2.9

Caliper Surveys 29/11/2007

02/06/2008

Application Trouble Shooting

�Emulsion formation

�Surfactants can potentially increase emulsion tendencies

�Foamer treatments are often managed with antifoam and emulsion breakers as required

�Field evidence demonstrates no impact on process

�Process upsets

�Proper topside foam control should prevent any disruptions

� Correct defoamer application

�No reported impact on water quality specification

Confidential 38


�No well response

�Dead well

� Insufficient gas or agitation

� Can rock or swab the well

� Apply gas sticks / pellets – introduce localised gas

�Flowing well

� Chemical not reaching the liquids

� Well conditions are not conducive to loading

– Modelling error


�Capstring issues

�Plugging of the line

� Use only capstring qualified products

� Apply appropriate flushing procedures for shut down

�Compatibility

� Materials

� Chemicals

� Produced fluids

Confidential 39

Continuous Improvement Application Program

1. Collate well data (as per questionnaire)

2. Model & rank wells3. Prepare product recommendation / trial proposal

4. Performance measurement method understood?5. Similar Case Studies / Best Practices6. Understand all criteria for success

7. Nalco support specialists defined?

1. Supply chain capabilities2. Storage needs3. Equipment for well application?

– what / who / when4. Well sample points adequate?

5. Source monitoring equipment

1. Base line completed

2. Stock / delivery monitoring3. Well variable / performance monitoring

4. Communication of results

1. Optimisation plan2. Troubleshooting guide

3. Develop Case Study4. Evaluate new technology

Select Programme

Monitor Performance

Plan / Design

Measure / Monitor

Learn / Improve Act / DoGas Well

Foamer

Programme ApplyReview / Continuous

Improvement

1. Collate well data (as per questionnaire)

2. Model & rank wells3. Prepare product recommendation / trial proposal

4. Performance measurement method understood?5. Similar Case Studies / Best Practices6. Understand all criteria for success

7. Nalco support specialists defined?

1. Supply chain capabilities2. Storage needs3. Equipment for well application?

– what / who / when4. Well sample points adequate?

5. Source monitoring equipment

1. Base line completed

2. Stock / delivery monitoring3. Well variable / performance monitoring

4. Communication of results

1. Optimisation plan2. Troubleshooting guide

3. Develop Case Study4. Evaluate new technology

Select Programme

Monitor Performance

Plan / Design

Measure / Monitor


Foamer


Improvement

Select Programme

Monitor Performance

Plan / Design

Measure / Monitor


Foamer


Improvement

Foamer Performance Summary

� See great versatility of the foamer application� On- and Off- Shore

� Continuous and Batch� Continuous is preferable in majority of instances

� Optimisation is facile with rapid response

� Performance observed:� Above the critical velocity

� When the casing is loaded

� Instead of and with plungers

� Benefits:� Increased production

� Improved decline curve

� Extended flowing period

� Well clear out

� Extend well longevity

� Can be used to support asset integrity and flow assurance programs� Reduce chemical inventory and injection hardware requirements

Confidential 40

Workshop Summary

�Demonstrated the benefits chemical foamers can offer gas producers

�Applying a robust selection and testing process means best suited products are recommended

�Utilising surfactant chemistry expertise and the fundamentals of foam science facilitates the development of efficient deliquification chemicals

Questions

Confidential 41

Referenced Material

� Gas Well Deliquification, J. Lea, H. Nickens, M. Wells, ISBN 0-7506-7724-4

� Zinterl M. “Foamer Squeeze - The Advancement of Foamer Batching”, Gas Well Deliquification Workshop, Denver, Colorado February 23 -26, 2009

� Willis M., Visser J. “Selection and Application of Chemical Foamers for Offshore, North Sea”, Gas Well Deliquification Workshop, Denver, Colorado February 23 -

26, 2009

� Willis M., Hudsen J. “Foamer Field Trials”, 2008 Gas Well Deliquification Conference, Groningen NL

� Conrad G., Nguyen D. “The Use of Foamer and Injection Nozzle for Increasing Gas Production“, Gas Well Deliquification Workshop, Denver, Colorado February 23 -26, 2009

� Pakulski M.“Automated High Pressure, High Temperature Foam Column Testing

Apparatus”, Gas Well Deliquification Workshop, Denver, Colorado February 23 -

26, 2009

� http://www.echometer.com/ (visited 7th August 2009)

� http://www.kruss.info/index.php?content=http%3A//www.kruss.info/instruments/b

p2_e.html (visited 20th May 08)

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