Phase-Conversion Stiffened Dual-Network Hydrogel for Fracture Plugging in Oil-Based Drilling Fluid

Area of Science:

• Materials Science
• Petroleum Engineering
• Polymer Chemistry

Background:

• Lost circulation during drilling operations causes significant fluid loss, environmental damage, and increased costs.
• Existing gel materials for fracture plugging have limitations in high-temperature stability and mechanical strength.
• Developing robust gels is crucial for efficient and environmentally sound drilling operations.

Purpose of the Study:

• To develop a high-temperature-resistant, phase-conversion stiffened dual-network hydrogel for oil-based drilling fluids.
• To enhance the mechanical properties and plugging performance of hydrogels under harsh downhole conditions.
• To investigate the mechanisms behind the improved properties of the modified hydrogel.

Main Methods:

• Synthesis of a double-network hydrogel.
• Phase-conversion treatment using ethylene glycol (EG), polyethylene glycol (PEG), and glycerol (Gly).
• Evaluation of mechanical properties (compressive strength), plugging efficiency, thermal stability (TGA), chemical composition (GC-MS), and chemical structure (ATR-IR).

Main Results:

• Phase-conversion significantly improved compressive strength and plugging efficiency at elevated temperatures.
• GC-MS revealed dehydration and reagent exchange, leading to increased solid content and oil-phase dominance after high-temperature treatment.
• ATR-IR confirmed hydrogen bond formation, contributing to gel strength.
• TGA indicated PEG enhances thermal stability, while EG has a negative effect, and Gly has a negligible influence.

Conclusions:

• The developed phase-conversion stiffened dual-network hydrogel offers superior performance for high-temperature drilling fluid applications.
• Enhanced gel strength is attributed to increased solid content from phase transformation and synergistic effects of dehydration and hydrogen bonding.
• This material presents a promising solution for mitigating lost circulation in challenging drilling environments.