Why Acid Placement Is Critical in Carbonate Acidizing

Matrix acidizing is one of the most effective stimulation methods for carbonate reservoirs. However, achieving successful acid stimulation depends not only on the acid formulation itself but also on how effectively the acid is distributed throughout the formation.

Without proper diversion, hydrochloric acid naturally flows into the highest permeability zones, leaving tighter intervals untreated. This uneven acid placement often results in:

• Limited stimulation effectiveness
• Poor reservoir coverage
• Excessive acid consumption
• Lower production improvement
• Reduced economic returns

To solve these challenges, Viscoelastic Surfactant (VES) Diverting Agents have become one of the preferred technologies in modern acidizing operations.

What Is a Viscoelastic Surfactant Diverting Agent?

A Viscoelastic Surfactant Diverting Agent is a specialized surfactant system that temporarily increases the viscosity of the acid during stimulation.

Unlike polymer-based diverting systems, VES technology forms reversible wormlike micelle structures instead of permanent polymer networks.

This temporary viscosity increase helps divert acid away from already stimulated high-permeability zones and into untreated intervals.

Once the acid reacts with the formation hydrocarbons or is diluted by formation water, the viscoelastic structure breaks naturally without leaving damaging polymer residues.

Advantages of VES Diverting Agents

Compared with conventional polymer diverting systems, VES technology offers several important advantages:

Excellent Temporary Diversion

The temporary viscosity increase effectively blocks dominant flow paths and redirects acid toward lower permeability zones.

Minimal Formation Damage

Since VES systems contain no guar gum or other polymer residues, they significantly reduce the risk of permeability impairment.

Easy Flowback

After stimulation, the viscoelastic structure breaks automatically, allowing easier cleanup and improved post-treatment production.

Improved Acid Efficiency

More uniform acid distribution means higher acid utilization efficiency and lower acid consumption.

Typical Applications

Viscoelastic Surfactant Diverting Agents are widely used in:

• Carbonate matrix acidizing
• Multi-stage acid stimulation
• Naturally fractured reservoirs
• Horizontal wells
• High permeability formations
• Selective acid diversion treatments

These applications help maximize reservoir contact while minimizing unnecessary acid losses.

Factors Affecting Diversion Performance

Several operational parameters influence VES performance:

Temperature

The surfactant formulation should be selected according to reservoir temperature to maintain sufficient viscosity during treatment.

Acid Concentration

Most VES diverting systems are compatible with hydrochloric acid concentrations commonly used in carbonate stimulation.

Formation Mineralogy

Reservoir lithology affects acid reaction rates and diversion efficiency.

Injection Rate

Proper pumping rates help maintain the desired diversion mechanism throughout the treatment.

Optimizing these factors ensures maximum stimulation effectiveness.

Selecting the Right Viscoelastic Surfactant Diverting Agent

When selecting a VES diverting agent, operators should evaluate:

• Reservoir temperature
• Acid compatibility
• Diversion efficiency
• Cleanup performance
• Formation damage potential
• Operational simplicity
• Cost effectiveness

Laboratory compatibility testing and core flow experiments are recommended before field application.

AC-VES Viscoelastic Surfactant Diverting Agent from Sichuan All-Chem

Sichuan All-Chem Chemical Co., Ltd. has developed AC-VES, a high-performance Viscoelastic Surfactant Diverting Agent specifically designed for acidizing stimulation in carbonate reservoirs.

AC-VES provides:

• Efficient temporary diversion
• Excellent compatibility with hydrochloric acid systems
• Low formation damage
• Easy cleanup after treatment
• Improved acid placement efficiency
• Reliable performance under demanding oilfield conditions

More product information is available here:

AC-VES Viscoelastic Surfactant Diverting Agent

https://www.scall-chemical.com/viscoelastic-surfactant-diverting-agent-ac-ves-2-product/

Frequently Asked Questions

Is a Viscoelastic Surfactant Diverting Agent better than polymer diverting agents?

In many carbonate acidizing applications, VES systems offer cleaner flowback, lower formation damage, and more efficient temporary diversion than conventional polymer systems.

Does VES leave residue?

No. Properly designed VES systems form reversible micellar structures rather than permanent polymer gels, resulting in significantly lower residue after treatment.

Can VES be used in high-temperature reservoirs?

Yes. High-temperature formulations are available for different reservoir conditions. Product selection should be based on reservoir temperature and acid system design.

What formations benefit most from VES diversion?

Carbonate reservoirs, naturally fractured formations, horizontal wells, and heterogeneous reservoirs typically achieve the greatest benefits from VES-based diversion systems.

Conclusion

As reservoir stimulation becomes increasingly focused on efficiency and formation protection, Viscoelastic Surfactant Diverting Agents are playing an increasingly important role in modern carbonate acidizing.

By improving acid placement, reducing formation damage, and simplifying post-treatment cleanup, VES technology helps operators achieve higher stimulation efficiency and better production results.

Sichuan All-Chem Chemical Co., Ltd. continues to provide reliable oilfield stimulation chemicals, including AC-VES Viscoelastic Surfactant Diverting Agent, supporting oil and gas operators worldwide with high-performance acidizing solutions.