What Is the Difference Between PAC HV and PAC LV? Filtration Control in Drilling Mud
PAC (Polyanionic Cellulose) is a cellulose-based polymer used in water-based drilling fluids to control filtration and improve filter-cake quality. The main practical difference between PAC LV and PAC HV is their contribution to mud viscosity.
What does PAC LV do?
PAC LV is selected to reduce filtration while increasing mud viscosity as little as practical. It can be advantageous when existing rheology is sufficient but filtration remains too high.
What does PAC HV do?
PAC HV provides filtration control together with a more pronounced viscosity and carrying contribution. It can be considered when both filtration and rheology support are required.
Main differences
| Property | PAC LV | PAC HV |
|---|---|---|
| Filtration control | High | High |
| Viscosity contribution | Low | Pronounced |
| System already has high viscosity | May be more suitable | Use carefully |
| Need filtration + viscosity | Limited | More suitable |
What should a good filter cake look like?
Filtrate volume alone is not enough. A thin, tight, low-permeability and reasonably smooth filter cake is generally preferred. Two fluids with the same filtrate volume can produce very different filter-cake behaviour.
What is the difference between PAC and CMC?
PAC and CMC are in the same cellulose-derivative family, but product structure, purity, salt tolerance and field performance can differ. See the CMC guide for more detail.
What is the difference between PAC and xanthan gum?
PAC is selected primarily for filtration control. Xanthan gum is used especially for low-shear rheology, suspension and cuttings transport. They can be used in the same system for different functions.
Do hardness and salinity matter?
Yes. PAC can perform well in many difficult-water conditions, but it should not be described as unaffected by hardness or infinitely salt tolerant. Test in the actual field water.
How should PAC be mixed?
Add PAC gradually under adequate turbulence and allow time for complete hydration. Adding it too quickly can cause lumps and reduce effective product use.
MUDOPAC LV and MUDOPAC HV
MUDOPAC LV is positioned for filtration control with low viscosity contribution; MUDOPAC HV provides filtration control with a more pronounced viscosity contribution.
Frequently asked questions
Filtration is high but viscosity is already sufficient. Which grade is the more direct candidate?
PAC LV may be the more direct candidate.
Filtration is high and viscosity is also low. What should be considered?
PAC HV can be evaluated, but the root cause of any cuttings-transport problem should also be examined.