PAC R

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The regular viscosity polyanionic cellulose (PAC-R) is a high-performance additive specially designed for oilfield drilling fluids. PAC R belongs to one kind of the high viscosity (HV) types of polyanionic cellulose (PAC), it has excellent viscosity increase, fluid loss reduction and wellbore stability functions, and PAC R is also suitable for a variety of complex drilling environments. As a widely used drilling fluid additive, PAC-R (polyanionic cellulose, regular viscosity) delivers predictable rheology control and filtration control in freshwater, brine and high-salinity conditions, helping engineers reduce non-productive time. Manufactured under controlled DS and molecular-weight distribution, PAC-R demonstrates high-temperature stability up to 150°C in laboratory aging tests and shows superior salt tolerance versus conventional cellulose derivatives. Bench and field data indicate API fluid-loss reductions of 30–60% at typical dosages and reliable suspension of barite in weighted mud systems, making PAC-R a cost-effective fluid loss reducer and borehole-stabilizing polymer for modern deep and complex well operations.

• 1. PAC R for Drilling fluid system optimization

  The Regular viscosity polyanionic cellulose(PAC R) has the ability of high-temperature deep well wall protection. The PAC R could maintain 70% of the initial viscosity in 120-150℃ formations, inhibit shale hydration expansion, and reduce the risk of drill bit sticking.

  In the saturated brine slurry PAC R can still maintain effective viscosity in 30% NaCl solution, and the PAC R could form a tough mud cake to seal the cracks in the salt-gypsum layer under 30% salt solution.

• 2. PAC R used in well completion and production increase operations

  PAC R used in solid-free fracturing fluid: The low-viscosity PAC R (5-20mPa・s) can be used to prepare high-conductivity fracturing fluid to reduce damage to the reservoir. Meantime the regular viscosity polyanionic cellulose could stable the workover fluid, it could suspend barite in high-density salt-based workover fluid, to avoid wellbore blockage caused by solid phase sedimentation.

• 3. PAC R for Chemical oil flooding efficiency enhancement

  • PAC R used in the salt-tolerant polymer flooding: The PAC R could keep a stable solution viscosity in oil reservoirs with a mineralization of 30,000 mg/L and calcium and magnesium ions of 1,000 mg/L, meantime the PAC R solution also could expand the swept volume, so that push the oil out from the well.
  • The PAC R could also used in the binary composite system. It works synergistically with surfactants to reduce the oil-water interfacial tension to 10⁻³mN/m and improve the microscopic oil washing efficiency.
  • Filtration control ability: The PAC-R, as a fluid loss reducer, can significantly reduce API fluid loss, prevent excessive penetration of drilling fluid water into the formation, and maintain wellbore stability.
  • Suspension stability: The PAC R could enhance the suspension ability of drilling fluid for drill cuttings, avoid solid phase particle sedimentation, and ensure drilling efficiency.

• 4. Some complex formation response that require PAC R

  In shale layers or easily collapsed formations, PAC-R reduces the risk of well wall collapse by inhibiting shale hydration dispersion, and it is suitable for shale gas extraction and other scenarios.

 

Evidence & Technical Notes - Field & Lab Performance

Bench and field evaluations of PAC-R (polyanionic cellulose, regular viscosity) demonstrate measurable performance under standardized testing protocols. In laboratory HPHT and API filtration tests, PAC-R reduced API fluid loss by 30–60% depending on mud composition and salinity; in saturated brine (30% NaCl) formulations PAC-R retained ≥70% viscosity after 16 hours at 120°C in controlled aging studies. Field trials in high-temperature deep wells reported improved borehole stability and reduced torque & drag events when PAC-R was used as a primary fluid-loss reducer and shale inhibitor. Typical handling and specification metrics (available on COA) include targeted molecular substitution parameters, viscosity profiles (measured at standard shear rates) and residual solids. For engineering procurement, we provide batch COA, lab protocol summaries, and accept third-party verification on request.

 

Application Case Examplesase 

Case 1 - Deep Sea High-Temperature Well (Client: anonymized)

Problem: Frequent viscosity loss and bit sticking at 140–160°C.

Solution: PAC-R at 0.6% with sulfonated phenolic resin; achieved viscosity retention ~72% after 16 hr thermal aging and reduced sticking incidents by 60% during the campaign.

Case 2 - High-Salinity Reservoir Profiling

Problem: Polymer precipitation in 30% NaCl brine.

Solution: PAC-R formulation with anti-calcium stabilizer maintained suspension and reduced API filtrate by 35% in core tests.

Advantage

1. High temperature resistance

The PAC R can maintain stable performance at high temperatures of 150°C, which is better than some traditional cellulose derivatives (such as CMC).

The thermal stability of PAC-R comes from its optimized anionic backbone and controlled molecular-weight distribution, which prevents chain degradation at elevated temperatures. After aging at 120–150°C, it can still retain about 70% of its initial viscosity while maintaining strong fluid-loss control, making it suitable for deep and geothermal wells. Compared with conventional CMC, PAC-R shows better anti-flocculation performance in high-salt and hard-ion environments, reducing on-site mud adjustments. For procurement, it enables lower dosage, more stable HPHT rheology, and fewer wellbore-related non-productive events.

2. Multifunctionality

PAC R has multiple functions such as viscosity increase, filtration loss reduction, and shale inhibition. So the regular polyanionic cellulose could reduce the types of chemicals that need to be added to the drilling fluid system.

PAC-R meets modern green-chemistry standards for onshore and offshore drilling. OECD tests and natural attenuation studies show faster breakdown than many synthetic polyacrylamides, reducing polymer accumulation in cuttings and produced water. Its low biocide requirement minimizes chemical loads, simplifies mud pit and cuttings management, and lowers disposal costs. PAC-R supports regulatory compliance and sustainability commitments, making it ideal for environmental managers and procurement teams seeking reliable, eco-friendly additives for complex oilfield operations while maintaining high drilling efficiency.

3. Environmental compatibility

The PAC R can be quickly degraded and no bactericide is required, which is in line with international environmental protection trends and helps green mining of oil fields.

PAC-R's biodegradation profile meets contemporary green-chemistry expectations for offshore and onshore operations. Under standardized OECD biodegradability assays and natural attenuation studies, PAC-R shows significantly faster breakdown than many synthetic polyacrylamides, reducing long-term polymer accumulation in cuttings and produced water. The reduced need for biocides lowers operational chemical loads and simplifies waste management for drill cuttings and mud pits. For environmental managers and purchasers, PAC-R supports regulatory compliance, lowers disposal costs, and aligns with sustainability commitments increasingly demanded by national regulators and international oil companies.

4.Supply Chain Reliability & Traceability

Our PAC-R offering includes full batch traceability and Certificate of Analysis (COA) for each production lot, covering viscosity, molecular parameters, moisture and performance indices such as API fluid loss. We maintain stable production throughput with controlled quality systems to support bulk procurement (MT-scale), minimizing lead-time variability for large offshore projects. Third-party testing and witnessed factory acceptance tests are available on request to satisfy engineering procurement and construction (EPC) contractors. This supply-chain transparency reduces commercial risk for wholesale buyers and ensures product performance matches engineering specifications on arrival at the rig site.

The stability and environmental friendliness of PAC-R significantly reduce the operational risks and maintenance costs. Currently, the regular viscosity polyanionic cellulose(PAC R) for oil fields is mainly used in shale gas horizontal wells, deep-sea high-temperature wells and high-salinity oil reservoir development. The future technical development directionsfor PAC R include:

1. Nanocomposite modification: Grafting montmorillonite nanosheets to increase temperature resistance to 180°C;

2. Biological synthesis: Using bamboo fiber instead of cotton linters as raw materials to reduce production costs by 20%;

3. Intelligent response: Developing pH-sensitive PAC-R, which automatically cross-links to form a plugging layer when encountering acidic formations.

Q1: Can I get a sample and COA before ordering?
A: Yes - we provide 200–500 g samples and COA for lab evaluation. Third-party testing can be arranged for major orders.

Q2: What dosage is typical for drilling fluids?
A: Common field dosages range 0.2–1.0 wt% depending on mud design, salinity and target filtration loss. We provide dosage optimization.

Q3: Is PAC R suitable for seawater or saturated brine systems?
A: Yes - PAC R maintains effective viscosity in up to 30% NaCl in controlled tests and is formulated to resist Ca²⁺/Mg²⁺ flocculation.

Q4: How long is lead time for bulk orders?
A: Typical lead time is 7–21 days depending on order volume and destination; expedited production can be discussed.

Q5: What documentation will you provide for export?
A: COA, MSDS, TDS, packing list and commercial invoice. Third-party inspection reports on request.

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