HEC
Application areas
1. Drilling Fluid Thickening and Filtrate Loss Control
- Function: As a thickener, it increases drilling fluid viscosity to stabilize wellbore; by adsorbing on clay particles to form a colloidal film, it reduces filtrate loss (mitigating risks of wellbore collapse caused by drilling fluid infiltration into formations).
- Scenario: Commonly used in water-based drilling fluids, especially for high-temperature deep wells (temperature resistance up to 150°C+), avoiding high-temperature failure of traditional starch-based treatments.
2. Completion Fluid and Workover Fluid Compatibility
- Function: In low-damage completion fluid formulation, it acts as a temporary plugging agent or thickener to adjust fluid rheology (e.g., control gel strength) and reduce formation damage; during workovers, it suspends solid particles (e.g., cuttings) for efficient circulation and removal.
- Advantage: Strong salt tolerance (adaptable to high-salinity formation water), compatible with various inorganic salts (e.g., KCl, CaCl₂).
3. Fracturing Fluid Thickening and Proppant Carrying
- Function: As a thickener for water-based fracturing fluids in hydraulic fracturing, it forms high-viscosity fluids to carry proppants (e.g., quartz sand) into fractures; after gel breaking, it easily flows back, minimizing impact on fracture conductivity.
- Comparison: Compared with guar gum, HEC has superior shear resistance (high viscosity retention during pumping), suitable for large-displacement fracturing in complex well conditions.
4. Oil Displacement Agents and Enhanced Oil Recovery (EOR)
- Function: In polymer flooding fluid formulation, it improves oil-water mobility ratio by increasing water phase viscosity to expand swept volume; compounded with surfactants, it forms low-interfacial-tension systems to enhance oil recovery (increase by 8%-15%).
- Requirement: Molecular weight control (usually high-molecular-weight grades) is needed to ensure solution stability under reservoir conditions (high salt, high temperature).
5. Oilfield Wastewater Treatment
- Function: As a flocculant to assist in treating oily wastewater, it agglomerates tiny oil droplets and suspended solids through adsorption bridging, improving sedimentation efficiency (better combined with PAC/PAM).
Core Advantages
- High-Temperature Stability: Temperature resistance up to 150-180°C, superior to most natural polymer treatments (e.g., carboxymethyl cellulose).
- Shear Recovery: Rapid viscosity recovery after shearing, suitable for cyclic operations (e.g., reused drilling fluids).
- Environmental Compatibility: Biodegradable, compliant with offshore oilfield environmental standards (e.g., API Spec 13A certification).
Typical Dosages: 0.3%-1.0% by weight in drilling fluids (based on water phase); up to 1000-3000ppm in flooding fluids, adjusted according to reservoir conditions.
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