Zr-N-SiO2 Water-Based Crosslinker Enables Efficient Extraction of Coalbed Methane

Aiming at the problem that traditional fracturing fluids are prone to failure in coalbed methane (CBM) extraction under deep high-temperature and high-shear environments, this study proposes a method to prepare Zr-N-SiO2 water-based crosslinkers using silane coupling agent-modified nano-silica as the inorganic framework combined with zirconium ions. The optimal fracturing fluid formulation is identified as 0.8 wt% Zr-N-SiO2 and 0.4% HPAM thickener. This formulation exhibits rapid viscosity recovery under cyclic shear, retains a viscosity exceeding 140 mPa·s at 180 °C, and maintains long-term viscosity stability across 90–180 °C, with operational viability even at 180 °C. Its gel-breaking performance is controllable: with 0.08 wt% ammonium persulfate, viscosity drops to 2.91 mPa·s within 480 min. With 0.10 wt%, it decreases to 2.762 mPa·s in 400 min. This research aims to offer a novel technical approach for efficient and eco-friendly CBM extraction, with significant theoretical and practical value.