UCST-Activated Network Reinforcement in Hybrid Microgels for Smart Plugging

Area of Science:

• Materials Science
• Polymer Chemistry
• Petroleum Engineering

Background:

• Conventional polymer plugging materials degrade in deep wells due to heat, compromising performance.
• Effective lost circulation control is critical for deep-well drilling operations.

Purpose of the Study:

• To develop a novel smart microgel (SUPA) for adaptive plugging in deep-well environments.
• To investigate the Upper Critical Solution Temperature (UCST)-responsive mechanism for enhanced material performance.

Main Methods:

• Synthesis of a dual-crosslinked hybrid microgel incorporating NAGA and HPMA functional units.
• Characterization using particle size analysis and oscillatory rheology in saline solutions.
• Evaluation of sealing performance in fractured models under high temperature (150 °C) and pressure (5 MPa).

Main Results:

• The SUPA microgel demonstrated UCST responsiveness, leading to polymer chain extension and volumetric expansion upon heating.
• A significant ~7.5-fold increase in storage modulus (G') indicated dynamic network reinforcement.
• SUPA-enhanced fluids showed improved rheological properties, including a 4.4-fold increase in low-shear viscosity and excellent thixotropic recovery.
• Reliable and highly efficient sealing was achieved under simulated deep-well conditions.

Conclusions:

• The developed UCST-responsive hybrid microgel (SUPA) provides a robust solution for lost circulation control.
• The mechanism-driven design strategy of UCST-activated network reinforcement is validated for harsh environments.
• SUPA offers a promising alternative to conventional plugging materials for deep-well applications.