PAC HV (Polyanionic Cellulose High Viscosity) is a chemically modified, water-soluble cellulose ether, a type of polyanionic cellulose. It is particularly suitable for use in saltwater wells and offshore drilling environments.
2. Physical and Chemical Properties of PAC HV
|
project |
Indicator range |
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Appearance |
White or light yellow free-flowing powder |
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Moisture |
≤10% |
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1% aqueous solution viscosity (Brookfield) |
≥1500–2000 mPa.s (slightly different for different manufacturers) |
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pH value (1% solution) |
6.5–8.5 |
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Solubility |
Soluble in cold water, insoluble in organic solvents |
3. Main Functions of PAC HV
1. Viscosity-enhancing effect : Increases drilling fluid viscosity (apparent viscosity ≥ 50.0 mPa·s), facilitating the suspension of cuttings and cleaning the wellbore, providing excellent cuttings-carrying capacity and optimizing drilling efficiency .
2. Filtration control : effectively reduces drilling fluid water loss (API filtration loss ≤ 18.0 mL), improves mud cake quality, and reduces the risk of downhole accidents .
3. Good thermal stability : The aqueous solution is stable below 80°C. When the temperature reaches nearly 150°C, it can still show a certain viscosity and can maintain it for about 48 hours. It has good heat resistance and stability and is suitable for high-temperature well drilling .
4. Excellent Product Performance: PAC HV substitution values typically range from 0.85 to 1.4. A high degree of substitution means more stable product performance, resulting in better performance in oil production applications. Performance is stable within a pH range of 3-11, making it suitable for use in a variety of polar environments, maintaining excellent performance in freshwater, saltwater, and saturated brine.
4. Scope of application of PAC HV
PAC-HV is easily dispersed in all water-based drilling fluids and is suitable for a variety of water-based drilling fluid systems, from freshwater to saturated brine. It is particularly well-suited for complex drilling conditions such as deep wells, high-temperature wells, brine wells, and offshore oil drilling. For example, it can be used as a viscosifier and stabilizer in water-based mud systems for oil and gas drilling fluids (freshwater, seawater, and brine systems) , geothermal wells, and high-temperature deep wells . It can also be used in non-oilfield industries such as mining and mud wall protection .
5. Usage and dosage
Recommended dosage : PAC HV can be directly mixed into water-based drilling fluid to take effect without complicated pretreatment; the recommended dosage is 10% of the total drilling fluid. 0.3%–0.8% (i.e., 3–8 kg/ton of mud) , adjusted depending on well conditions and formulation . Suitable for all oil and gas drilling projects, especially offshore and deep well operations .
Addition method : It can be directly added slowly into stirred clean water to dissolve, stirred evenly to form a uniform solution and then added into the drilling fluid system.
6. Packaging and storage
Packaging : Usually 25kg kraft paper bag or PE woven bag lined with moisture-proof film bag.
Storage conditions : Store in a dry and ventilated place, avoid moisture, and avoid mixing with strong oxidants.
Shelf life : 2 years under normal storage conditions .
7. Notes
When preparing PAC HV solution, avoid high shear stirring for too long to prevent degradation.
If used in a high-salt, high-calcium environment, it is recommended to use modified PAC HV products with better salt resistance.
