This study presents a practical method for preparing an alkaline zirconium-based crosslinker designed to address the issue of rapid crosslinking commonly observed with conventional acidic zirconium crosslinkers in hydraulic fracturing applications. Zirconium ions, characterized by multiple vacant orbitals and high charge density, offer effective crosslinking sites that enhance the thermal stability and gel strength of fracturing fluids. However, the rapid reaction rate of standard acidic zirconium crosslinkers often leads to premature gelation within the wellbore, increasing frictional resistance and causing shear degradation of the gel.
To introduce a delayed-crosslinking property, an organic complexation approach was employed. Using zirconium oxychloride as the zirconium source, triethanolamine served as the primary ligand due to its three hydroxyl groups and lone electron pairs, enabling strong coordination with zirconium under both acidic and alkaline conditions. Glycerol was added as a secondary ligand to further modulate the crosslinking rate. An alkaline organic zirconium crosslinker was synthesized via a hydrothermal method, and its chemical structure was characterized.
The resulting crosslinker was evaluated in seawater-based fracturing fluid systems using two types of thickeners: carboxymethyl hydroxypropyl guar gum (CMHPG), a modified guar derivative with improved solubility and industrial availability, and nonionic polyacrylamide (NPAM), a synthetic polymer with potential for high-salinity environments. Both thickeners were mixed with the synthesized crosslinker in artificial seawater to form fracturing fluid gels. The CMHPG-based system exhibited stable gel formation with controlled crosslinking kinetics, while the NPAM-based system showed promise for use in high-salinity or produced water conditions due to its nonionic nature and good solubility.
Overall, this work provides a reproducible method for preparing an alkaline zirconium crosslinker with delayed crosslinking behavior, suitable for formulating seawater-based fracturing fluids with reduced premature gelation risk and improved compatibility with modified guar and synthetic polymer thickeners.
Post time: Apr-03-2026