PAC LV HV polyanionic cellulose drilling fluid

Advantages of Using PAC in Drilling Operations

One of the standout benefits of using Polyanionic Cellulose (PAC) in oil well drilling is its ability to dramatically enhance filtration control. When drilling through highly permeable or fractured formations, maintaining wellbore integrity becomes challenging. PAC excels by forming a consistent, resilient filter cake that seals pores and microfractures effectively.

This translates to:

• Significant reduction in fluid loss rates (typically <10 mL in API tests)

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• Prevention of stuck pipe incidents

• Protection against formation damage

• Enhanced cementing operations due to controlled fluid flow

PAC’s ability to maintain a thin yet robust filter cake even under dynamic drilling conditions ensures smooth operations from spud to total depth.

Improved Wellbore Stability

PAC contributes not just to fluid loss control but also to overall wellbore stability. By inhibiting shale hydration and preventing cuttings dispersion, PAC helps maintain clean, gauge boreholes.

Additional benefits include:

• Improved hole cleaning and less risk of wellbore collapse

• Reduced torque and drag on the drill string

• Enhanced rate of penetration (ROP)

Because PAC is compatible with both low and high-density muds, it offers flexibility across different geological environments.

Here’s how to mix PAC-LV (Polyanionic Cellulose Low Viscosity) during an oil well drilling job, in simple and practical terms:

How to Mix PAC-LV During Well Drilling

1. Understand Why You’re Using It

PAC-LV is mainly used for:

• Controlling fluid loss (forming a thin filter cake)

• Improving shale stability

• Minimizing formation damage

• Maintaining mud performance without thickening it too much

You typically add PAC-LV to water-based drilling fluids or brine-based mud systems. It’s ideal when you want better filtration control but don’t want the mud to become too viscous.

2. Equipment You’ll Need

• Mixing hopper (Venturi hopper connected to the mud system)

• Agitated mixing tank or mud pits

• PAC-LV bags (usually 25 kg) or bulk sacks

• Clean freshwater or brine for pre-hydration (if needed)

• Personal protective equipment (PPE) — gloves, goggles, dust mask

3. Recommended Mixing Steps

1: Prepare the System

First, keep the mud system circulating to help PAC-LV mix evenly.
Next, check the pH level—PAC works best when the pH stays between 7 and 9.
If you can, mix PAC-LV in clean freshwater before adding it to the system. This helps it hydrate more effectively.

2: Initial Addition

• Slowly add PAC-LV into the mixing hopper.

• Typical concentration is between 0.5 to 2.0 lb/bbl (that’s about 1.5 to 6 kg per cubic meter of mud).

  • For fluid loss control: Start with 1 lb/bbl (about 3 kg/m³).

  • Increase if API fluid loss is still too high.

3: Monitor Mixing

• Allow the mud to circulate for 15–30 minutes after adding PAC-LV.

• Ensure the product is fully dissolved — no lumps or fish eyes should remain.

• If using high-salinity or seawater mud, pre-hydrate PAC-LV first in freshwater if possible to avoid incomplete mixing.

4: Testing

• After mixing, perform a mud check:

  • API fluid loss test

  • Check mud viscosity (PAC-LV should not increase viscosity too much)

  • Check filter cake quality

5: Adjust as Needed

• If fluid loss is still higher than desired:

  • Add more PAC-LV in small increments.

• If the mud gets too thick (which is rare with PAC-LV):

  • Adjust by reducing other viscosifiers like bentonite.

4. Tips for Best Results

Always add PAC-LV slowly and evenly — rushing it into the system can cause lumps.
For salt-saturated or high-calcium systems, use specially treated PAC grades for better solubility.
Monitor the mud properties every few hours, especially in dynamic drilling situations (high fluid loss formations, long horizontal wells).
PAC-LV can be added in sweeps if you’re targeting specific intervals with high fluid loss or shale issues.

Summary Mixing Guide (Quick Table)

Environmental Benefits

PAC is derived from natural cellulose and is considered biodegradable under aerobic conditions. This makes it a preferred choice for operators seeking environmentally responsible drilling solutions.

PAC’s use in synthetic-based muds and low-toxicity water-based muds helps reduce the environmental impact of drilling waste and minimizes long-term formation damage.

PAC Grades and Their Applications

Low Viscosity PAC (PAC-LV)

• Purpose: Primarily designed for fluid loss control without significantly altering mud viscosity.

• Applications: Shale inhibition, filtration control in WBMs and SBMs.

Regular Viscosity PAC

• Purpose: Offers a balance of viscosity enhancement and fluid loss control.

• Applications: General-purpose additive for vertical and deviated wells.

High Viscosity PAC (PAC-HV)

• Purpose: Increases both fluid viscosity and filtration control.

• Applications: Used in challenging wells requiring enhanced cuttings suspension and shale stabilization.

PAC Application Techniques

PAC Addition Process

Adding PAC to drilling fluids is a relatively straightforward process:

1. Pre-mix PAC with water or brine in a mixing tank to ensure full hydration.

2. Add gradually to the active mud system under agitation to avoid lump formation.

3. Monitor mud properties using standard API filtration tests and adjust PAC concentration as needed.

Monitoring PAC Concentration

You can usually add PAC in concentrations between 0.5 and 3.0 lb/bbl (1.5 to 8.5 kg/m³), depending on the well conditions and the level of fluid loss control you need.
To get the best results, check the mud regularly. Also, avoid using too much PAC because it can make the mud too thick and slow down the drilling process.

PAC Performance in Various Well Conditions

High Temperature and High Pressure (HTHP) Wells

PAC demonstrates excellent thermal stability up to about 150–180°C (302–356°F) depending on its molecular structure and formulation.

In HTHP wells:

• PAC helps maintain filtration control under extreme conditions.

• Specialized PAC variants with enhanced thermal resistance are available for deep, hot wells.

Deepwater Drilling Operations

In deepwater environments:

• PAC’s compatibility with seawater-based muds is invaluable.

• It ensures low permeability filter cakes under low temperature/high pressure conditions.

• PAC mitigates risks of riser mud losses and helps maintain well control.

Comparing PAC with Other Fluid Loss Additives

PAC vs. Starch

Polyanionic Cellulose vs. CMC (Carboxymethyl Cellulose)

PAC offers faster hydration and better filtration control compared to CMC, especially in high-salinity environments.

PAC vs. Synthetic Polymers

Synthetic polymers may offer superior high-temperature performance, but they are often more expensive and less biodegradable than PAC.

Packing Details and Application

Packing Details

PAC is typically packed in:

• 25 kg multi-ply paper bags with inner plastic lining.

• 500 kg and 1000 kg jumbo bags for bulk handling.

• Custom packaging is also available upon request to meet specific logistical needs.

Storage: PAC should be stored in a cool, dry area away from direct sunlight and moisture to preserve its quality and performance.

Application Summary

• Oil and gas well drilling

• Workover and completion fluids

• Horizontal directional drilling (HDD)

• Geothermal drilling

• Core drilling

• Mining and tunneling applications

PAC’s versatility extends beyond oilfield use. It’s also employed in civil engineering, mining, and environmental protection operations.

Price Information

As of mid-2025, typical market prices for PAC are as follows:

Note: Prices vary based on order volume, packaging type, and delivery terms. Bulk purchasing and long-term contracts generally offer better pricing.