High-Strength Controllable Resin Plugging Agent and Its Performance Evaluation for Fractured Formation.

Area of Science:

• Drilling Engineering
• Materials Science
• Chemical Engineering

Background:

• Lost circulation poses significant risks in drilling, including wellbore instability and blowouts.
• Effective plugging materials are crucial for safe and efficient drilling operations.
• Urea formaldehyde resin offers high temperature resistance and strength for lost circulation control.

Purpose of the Study:

• To develop and optimize a urea formaldehyde resin-based plugging agent for lost circulation.
• To evaluate the performance of the developed plugging agent under various conditions.
• To provide a novel solution for drilling fluid loss in fractured zones.

Main Methods:

• Optimizing urea formaldehyde resin formula with additives like betaine, silane coupling agent KH-570, ammonium chloride, hexamethylenetetramine, and sodium carboxymethyl cellulose.
• Investigating rheological and curing properties at optimal temperatures (60-80 °C) and curing times (1-3 h).
• Assessing the impact of salt ions (Na+, Ca2+) and fracture characteristics on plugging performance.

Main Results:

• An optimized resin plugging agent system was prepared with controllable curing properties.
• The system exhibited stable viscosity and behaved as a viscous fluid before curing.
• Formation water with Na+ enhanced curing strength and reduced time, while Ca2+ increased time and reduced strength.
• Effective plugging was achieved in various fracture types and sizes, with breakthrough pressures up to 9.98 MPa.

Conclusions:

• The developed high-strength curable resin plugging agent system effectively addresses lost circulation in fractured zones.
• The system demonstrates excellent plugging performance and high breakthrough pressure under simulated downhole conditions.
• This research offers valuable insights and practical applications for drilling fluid loss mitigation.