Best Practices: Chemical Selection for Gas Well Deliquification Laboratory Measurements...

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Best Practices: Chemical Selection for Gas Well Deliquification

Laboratory MeasurementsJose M Macias, Danny Lillard, Joel Gonzalez

ALRDC/SWPSC 2006 Gas Well Deliquification WorkshopFebruary 27 - March 1, 2006

One. Champion Infinite Solutions.Gas Well Deliquification Workshop, Denver – February 27 – March 1

Presentation Overview• Foam Basic principles applied to chemical selection• Foam requirements for gas well deliquification• Measurements of foaming in laboratory• Chemical families performance in laboratory• Parameters for Chemical Selection• Laboratory Chemical Selection vs field performance

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Foam Basic Principles• Foam stability influenced by interfacial properties.

– Film drainage and surface elasticity


Foam Basic Principles• Foam stability influenced by gas volume fraction.

– Stability Increases with increase in gas volume fraction– Dependant on mechanism of formation

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Foam Basic Principles

• Foam stability influenced by presence of hydrocarbon.

– De-stabilizes foam structure but can be carried in foam structure.


Foam Requirements for Gas Well Deliquification

• Provide foam stability to carry liquids to surface.• Provide Mechanism for hydrocarbon removal.• Break at surface before entering surface equipment.

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Standard Test Methods for Measurement of Foam and Evaluation of Surfactants

• ASTM D-3519 and modifications– Foam in Aqueous media (Blender Test)

• ASTM D-892 and modifications– Column Test Method

• ASTM D-3601 and modifications– Foam in Aqueous media (Bottle Test)


ASTM D-3519 and modificationsFoam in Aqueous media (Blender Test)

• Measurement of foam height and half life.• Measurement of drainage half life.

Foam height

Foam life Drainage Half Life

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• Foam generated with high shear thus stability high.• High shear can “shear” some foams dependant on surfactant used thus foam height lowered• Some surfactants prone to generate more foam in high shear conditions (would tend to

perform better in test)



• Ether sulfates prone to generate “more” foam than amphoteric surfactants.• Gas volume ratios vs foam height

– Ether sulfate - 1500ppm, 200mL 50,000 Cl – Brine• Foam Height 600mL , Gas Volume Ratio 0.35• Drainage time – 1min 25 sec

– Amphoteric - 1500ppm, 200 mL 50,000 Cl – Brine• Foam Height 520mL , Gas Volume Ratio 0.40

• Drainage Half Life 1min 10 sec

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• Useful for foam characterization under high shear conditions• Limited value to dynamic well unloading ,not predictive.• Use for surfactant comparison for well unloading dependant on what characteristic of foam

being investigated• Hydrocarbon influences cannot be considered because foam height severely reduced.


ASTM D-892 and modificationsColumn Test Method

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• Measure fluid carry over with given gas rate. (0.01ft/sec – 10ft/sec)• Measure foam height, foam life, and drainage time

– Gas rate influences foam characteristic– Lower gas rates produce more stable foam



• At higher gas rates, foam characteristics become more dynamic and better simulate deliquification conditions

– Metastable foam, foam film drainage, foam slugs

• Can be used with hydrocarbon.

• Lowered gas rates begin to remove dynamics from test

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Column Test 1000 PPM Surfcactant, 200mL initial volumeGas Velocity 0.5ft/sec,50,000 Cl Brine

95% Brine/ 5% Condensate

0

20

40

60

80

100

120

140

Amphoteric Ether Sulfate Anionic Cationic

Chemical Family

Ove

rflo

w (m

l)

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• Can be used to differentiate surfactants.• Predictability of foaming ability of surfactants in dynamic situation.• No preset criteria of “pass” but based on models can put minimum overflow dependent on

system.


ASTM D-3601 and modificationsFoam in Aqueous media (Bottle Test)

• Measurement of foam height and life.• Low shear and gas volume ratios dependant on gas volume available in bottle.• Useful for gross determination of “foaminess”.• No bias to chemical families observed.• Limitation on dynamic system predictability.

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Parameters for Chemical Selection

• Thermal stability • Fluid compatibility (Cl-,solids,etc)• Dynamic foam characteristic (well deliquification)• Foam life in well bore, ability to carry hydrocarbon• Delivery (application method).


Process for Chemical Selection

• Identify candidate well – modeling.• Select products that meet parameters. • Foam testing to differentiate products and confirm foaming ability.

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Laboratory selection vs field performance

• Selection of products that “failed” preset blender tests criteria have performed in the field.• Selection by column tests used to identify best surfactant for deliquification.


Conclusions• Laboratory measurements can be used study basic foam principles.• Foam measurements must take into account process where foam is to be applied.• For dynamic well deliquification, column testing is most applicable.

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Best Practices: Chemical Selection for Gas Well Deliquification Laboratory Measurements...

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