Ammonium Persulphate Encapsulated Gel Breaker

Encapsulated Ammonium Persulphate Gel Breaker at a Glance

Ammonium Persulphate Encapsulated Gel Breaker is a controlled-release oxidative breaker developed for polymer-based hydraulic fracturing fluids. It consists of an ammonium persulfate, or APS, active core protected by a specially designed coating.

The coating limits premature contact between APS and the fracturing-fluid polymer during surface mixing, pumping and proppant placement. Under the selected downhole conditions, the coating allows or triggers release of the oxidizing active, which degrades polymer chains and reduces fluid viscosity for cleanup and flowback.

The product may also be described as Encapsulated Ammonium Persulfate, Coated APS Breaker, Controlled-Release Persulfate Breaker or Delayed Gel Breaker.

• Product type: Controlled-release oxidative gel breaker

• Active core: Ammonium persulfate

• Active CAS number: 7727-54-0

• Active formula: (NH₄)₂S₂O₈

• Finished-product CAS: Mixture; not normally represented by one CAS number

• Typical form: Coated free-flowing granules

• Primary application: Hydraulic fracturing-fluid viscosity reduction

• Release principle: Time-, temperature-, diffusion- and/or stress-controlled

• Chemical category: Encapsulated inorganic oxidizer formulation

Available release profiles, active content and particle-size ranges must be confirmed against the selected product grade and Technical Data Sheet.

How Encapsulated APS Gel Breaker Works

Ammonium persulfate produces reactive oxidizing species after release and activation in the aqueous fracturing fluid. These species attack the long polymer chains responsible for fluid viscosity, reducing their molecular weight and allowing the fluid to lose viscosity.

The coating delays this reaction so that the fracturing fluid can retain sufficient viscosity while it is being pumped and transporting proppant.

Controlled-Release Sequence

1. Coated breaker granules are added to the fracturing-fluid system.

2. The protective coating limits immediate dissolution of the APS core.

3. The intact fluid maintains viscosity during pumping and proppant transport.

4. Water, temperature, time, pressure or mechanical stress affects the coating.

5. APS is progressively released into the fluid.

6. Oxidation reduces polymer molecular weight and fluid viscosity.

7. The spent fluid can flow back more easily from the fracture and proppant pack.

The actual release mechanism depends on the coating chemistry and particle design. It may involve diffusion, coating permeability, erosion, swelling, cracking under stress or a combination of mechanisms.

Why Encapsulation Matters

Uncoated ammonium persulfate can begin reacting as soon as it dissolves in the aqueous fluid. If activation occurs too early, the fracturing fluid may lose viscosity before completing proppant placement.

Encapsulation can help:

• Delay initial breaker activity

• Maintain pumping viscosity

• Preserve proppant-carrying capacity

• Permit a higher total breaker concentration

• Distribute breaker through proppant-laden stages

• Promote more complete polymer degradation

• Improve cleanup of the proppant pack

• Reduce residual polymer damage

• Support more predictable flowback timing

• Improve retained fracture conductivity

These benefits depend on matching the release profile to the fluid system and downhole conditions. Encapsulation does not guarantee performance without laboratory qualification.

Encapsulated vs Unencapsulated APS Breaker

The two products should not be substituted on an equal-weight basis without correcting for active APS content and release efficiency.

LT, MT, HT and XHT Breaker Selection

“Low temperature,” “medium temperature,” “high temperature” and “extra-high temperature” are product-series descriptions rather than universal industry specifications.

LT Encapsulated Breaker

An LT grade is designed to release at comparatively lower bottomhole temperatures. It may use a thinner, more permeable or more readily activated coating.

Selection considerations include:

• Minimum bottomhole temperature

• Need for a low-temperature activator

• Pumping time

• Shut-in time

• Fluid pH

• Salinity

• Desired final break time

MT Encapsulated Breaker

An MT grade provides an intermediate release profile for moderate-temperature treatments.

It may be selected when an LT product releases too quickly but an HT coating would delay cleanup excessively.

HT Encapsulated Breaker

An HT grade uses a more temperature-resistant or less permeable coating to limit premature release at elevated temperatures.

It is commonly evaluated for:

• Longer pumping schedules

• High-temperature reservoirs

• High breaker concentrations

• Crosslinked guar systems

• Treatments requiring delayed cleanup

XHT Encapsulated Breaker

An XHT product is designed for more demanding thermal exposure and extended treatment conditions.

The buyer should request release curves and fluid-break data at the actual bottomhole temperature rather than relying only on the XHT designation.

Information Required to Select the Correct Breaker

Breaker selection should be based on the entire treatment design.

Provide the supplier with:

• Static bottomhole temperature

• Estimated dynamic treatment temperature

• Total pumping time

• Expected shut-in time

• Base-fluid composition

• Fluid pH

• Total dissolved solids

• Calcium, magnesium and iron content

• Polymer type and concentration

• Crosslinker chemistry

• Proppant type and loading

• Additive sequence

• Desired break time

• Maximum permitted early viscosity loss

• Target final viscosity

• Required cleanup or conductivity result

Two wells at the same static temperature may require different breaker grades because their pumping time, fluid chemistry, pressure and proppant schedule differ.

Typical Product Quality Parameters

A specification stating only “encapsulated ammonium persulfate” is not sufficient for technical comparison.

How to Compare Release Curves

A release result has meaning only when the test conditions are stated.

Every release curve should identify:

• Test temperature

• Test duration

• Water or brine composition

• pH

• Calcium and magnesium concentration

• Test pressure

• Agitation or shear

• Presence of proppant

• Breaker concentration

• Particle-size range

• Analytical method

• Sampling intervals

• Whether release is reported as APS, persulfate or active oxygen

A product showing slow release in fresh water at atmospheric pressure may behave differently in high-salinity fluid, under closure stress or after abrasive contact with proppant.

Release Mechanisms and Downhole Conditions

Temperature

Higher temperature generally accelerates water penetration, coating change, persulfate activation and polymer oxidation. The magnitude of this effect depends on the coating and fluid chemistry.

Time

The release profile must protect the fluid for the required pumping period while still allowing cleanup within the planned shut-in and flowback schedule.

Pressure and Mechanical Stress

Pumping, perforation passage, proppant contact and fracture closure can damage or rupture a coating. Mechanical strength should be sufficient to prevent excessive surface release while still supporting the intended downhole mechanism.

pH

Persulfate activity, polymer stability and coating behavior can all change with pH. Testing should use the expected fracturing-fluid pH rather than neutral laboratory water unless neutral water represents the field system.

Salinity

Chlorides, hardness ions and total dissolved solids can influence coating permeability, APS dissolution and polymer-breaking performance.

Proppant

Coated particles can experience abrasion and crushing when transported with proppant. Release testing without proppant may underestimate mechanical damage.

Fracturing-Fluid Compatibility

Encapsulated APS breakers are commonly evaluated with polysaccharide-based fracturing fluids, including:

• Guar

• Hydroxypropyl guar

• Carboxymethyl hydroxypropyl guar

• Linear gels

• Borate-crosslinked gels

• Selected metal-crosslinked systems

• Foamed gel systems

Compatibility must also be checked with:

• Crosslinkers

• Buffers

• Clay stabilizers

• Surfactants

• Scale inhibitors

• Biocides

• Friction reducers

• Iron-control agents

• Mutual solvents

• Brines and recycled water

A breaker compatible with one guar and crosslinker package may not provide the same result with another system.

Applications of Encapsulated Ammonium Persulfate Gel Breaker

The product is intended for treatments requiring polymer viscosity during placement followed by delayed and controlled viscosity reduction.

Guar-Based Hydraulic Fracturing

Encapsulated APS is commonly used to degrade guar and guar-derivative polymers after they have transported proppant into the created fracture.

The controlled release helps separate the proppant-placement period from the gel-breaking period.

Crosslinked Gel Systems

Crosslinked fluids can provide high viscosity and proppant suspension but may require a greater degree of polymer degradation during cleanup.

Breaker selection should consider both the polymer backbone and crosslinking chemistry.

High-Proppant-Concentration Treatments

Higher breaker loading may be required to distribute active material throughout a dense proppant pack. Encapsulation can limit the early viscosity reduction that would otherwise result from increasing uncoated breaker concentration.

Long Pumping Schedules

Treatments with extended pumping times require sufficient coating integrity to prevent excessive APS release before placement is completed.

High-Temperature Wells

HT and XHT coatings can delay release during elevated-temperature exposure. Actual temperature capability must be established through dynamic rheology and release testing.

Formation-Cleanup Programs

Encapsulated breaker can form part of a cleanup strategy intended to reduce polymer residue and improve flowback. Conductivity, regained-permeability or proppant-pack testing should be used to validate the complete treatment design.

Laboratory Qualification Program

A technically useful breaker evaluation should include more than a bottle test.

Baseline Fluid Test

Measure the fracturing fluid without breaker to establish its thermal stability and normal viscosity profile.

Early-Time Viscosity Test

Confirm that the selected breaker concentration does not cause unacceptable viscosity loss during the intended pumping period.

Dynamic Rheology Test

Evaluate viscosity under representative temperature, shear and time conditions.

Release-Rate Test

Measure initial and cumulative APS release under representative brine, pH, temperature and pressure conditions.

Final Break Test

Measure final viscosity after the planned break period. Define the measurement temperature and shear rate.

Residue Test

Determine insoluble or filterable residue from both polymer degradation and coating material.

Conductivity or Permeability Test

Where performance risk justifies it, test the treated fluid in a proppant pack or formation-core system.

Compatibility Test

Check for precipitation, coating damage, unexpected gas generation, color change or performance loss when the breaker is combined with the complete additive package.

Breaker Dosage Considerations

There is no universal dosage for encapsulated APS.

The required concentration depends on:

• Polymer loading

• Polymer type

• Crosslink density

• Active APS percentage

• Coating percentage

• Temperature

• Pumping and shut-in time

• Fluid pH

• Water salinity

• Desired final viscosity

• Cleanup target

• Proppant concentration

• Other breakers or activators

Dosage should be established through laboratory testing and confirmed by qualified stimulation personnel. Published competitor dosages should not be transferred directly to another breaker grade.

Common Causes of Unexpected Breaker Performance

Premature Viscosity Loss

Possible causes include:

• Incorrect temperature grade

• Excess fines

• Coating damage during handling

• Abrasion by proppant

• Excessive shear

• High temperature

• Chemical incompatibility

• Excess breaker concentration

Delayed or Incomplete Break

Possible causes include:

• Coating that is too resistant

• Low downhole temperature

• Insufficient time

• Low active APS loading

• Inadequate breaker concentration

• High polymer loading

• Unexpected fluid chemistry

• Poor breaker distribution

Inconsistent Release

Possible causes include:

• Broad particle-size distribution

• Segregation during transport

• Moisture exposure

• Variable coating thickness

• Damaged packaging

• Inadequate sampling

• Non-representative laboratory test conditions

Packaging and Storage

Encapsulated breaker may be supplied in approved moisture-resistant bags, pails, drums or bulk containers. Actual packaging depends on the grade, transport classification and customer requirements.

Store the product:

• In its original tightly closed packaging

• In a cool, dry and ventilated area

• Protected from moisture and direct heat

• Away from reducing agents and incompatible chemicals

• Away from unapproved combustible contamination

• Under the temperature conditions stated in the SDS

• With oxidizing chemicals segregated according to local requirements

Rough handling, crushing or repeated transfer can create fines and damage the coating.

Use clean, dry equipment for sampling and transfer. Never return contaminated material to the original package.

Safety and Transport Considerations

The active ammonium persulfate core is a strong oxidizing agent. Encapsulation controls release but does not eliminate the underlying chemical hazard.

Depending on the product composition, the finished formulation may be classified for:

• Oxidizing properties

• Harmful effects if swallowed

• Skin irritation

• Eye irritation

• Respiratory irritation

• Skin sensitization

• Respiratory sensitization

Use suitable ventilation, chemical-resistant gloves, protective clothing and eye/face protection. Avoid inhaling dust and prevent contact with incompatible materials.

Some encapsulated APS products are transported as UN 1444, Ammonium Persulfate, Class 5.1, Packing Group III. However, transport classification can vary with coating composition, active content and jurisdiction.

Always use the shipment-specific SDS and transport documentation rather than assigning the uncoated APS classification automatically.

Documentation for Supplier Qualification

Buyers may request:

• Certificate of Analysis

• Safety Data Sheet

• Technical Data Sheet

• Product specification

• Active APS declaration

• Coating-percentage declaration

• Particle-size distribution

• Initial-release result

• Cumulative-release curve

• Temperature-specific rheology data

• Moisture result

• Active-oxygen result

• Mechanical-strength data

• Residue data

• Compatibility test results

• Country-of-origin statement

• Transport classification

• Shelf-life or retest statement

• Change-notification policy

• Packaging specification

Test methods and conditions should accompany performance data.

What to Include in an Encapsulated Breaker RFQ

For an accurate technical recommendation and quotation, provide:

1. Required LT, MT, HT or XHT grade

2. Bottomhole static temperature

3. Estimated dynamic treatment temperature

4. Pumping time and shut-in time

5. Polymer type and concentration

6. Crosslinker type

7. Fluid pH

8. Water salinity and hardness

9. Proppant type and loading

10. Target break time

11. Target final viscosity

12. Required APS active content

13. Required particle-size range

14. Packaging preference

15. Order quantity and annual demand

16. Delivery country, city or port

17. Required technical and regulatory documents

Frequently Asked Questions

What is an Encapsulated Ammonium Persulfate Gel Breaker?

It is a controlled-release oilfield additive containing an ammonium persulfate oxidizer core protected by a coating. It is designed to delay polymer degradation until after fracturing-fluid placement.

Why is ammonium persulfate encapsulated?

Encapsulation limits premature contact between APS and the polymer, helping the fluid maintain viscosity during pumping and proppant transport.

What is the CAS number?

The APS active core has CAS No. 7727-54-0. The finished encapsulated product is a mixture and may not have one CAS number.

Is the product organic or inorganic?

The active ammonium persulfate core is inorganic. The complete product is a composite formulation containing an inorganic oxidizer and usually an organic or polymeric coating.

Is it a fine chemical or an intermediate?

It is a specialty fine chemical and oilfield performance additive. It is not normally classified as a chemical intermediate.

What is the difference between LT and HT encapsulated breaker?

LT grades are designed for release at comparatively lower temperatures. HT grades use a more resistant coating to delay release under higher-temperature conditions. The actual temperature ranges are product-specific.

Can encapsulated APS replace uncoated APS directly?

Not on an equal-weight basis. The active APS content is lower because part of the product mass is coating, and the release profile differs.

Does encapsulated APS work with all fracturing fluids?

No. It must be tested with the actual polymer, crosslinker, brine and additive package.

What controls the release rate?

Release can be affected by temperature, time, coating thickness, particle size, pH, salinity, pressure, mechanical stress and proppant abrasion.

Does the coating completely prevent early release?

No coating provides absolute isolation under every condition. Initial release and fines content should be included in the product specification.

How is breaker performance evaluated?

Useful tests include release rate, dynamic rheology, early-time viscosity, final break viscosity, residue, compatibility and proppant-pack conductivity.

Is encapsulated APS still an oxidizer?

Yes. The coating controls exposure and release but does not remove the oxidizing hazard of the APS core.

How should the correct dosage be determined?

Dosage should be determined by laboratory testing under representative fluid, temperature, shear, salinity and time conditions.

Request an Encapsulated APS Gel Breaker Quote

Send us your bottomhole temperature, pumping time, fluid system, polymer loading, water chemistry, required break time, packaging and delivery destination.

We will evaluate the appropriate release grade and confirm the available APS content, particle-size range, specification, technical documentation and commercial terms.