Novel Mussel-Inspired High-Temperature Resistant Gel with Delayed Crosslinking Property for Ultra-Deep Reservoir Fracturing

Mussel-inspired materials have been widely studied due to their excellent adhesion and self-healing properties, but few studies have introduced this interesting property into the fracturing development of deep/ultra-deep oil and gas fields. Herein, a new type of mussel-inspired delayed crosslinking gel fracturing fluid is reported, which is formed by mussel-inspired polymers containing many catechol groups and organic zirconium delayed crosslinkers. The strong supramolecular interaction in mussel-inspired polymers can construct a more complex and stable dually cross-linked polymer network based on conventional chemical crosslinking, to cope with harsh conditions such as high temperature and shear in reservoirs. After shearing at 200 degrees C, the reserved viscosity of mussel-inspired delayed crosslinking gel is as high as 95 mPa center dot s. More importantly, the viscosity of gel remains basically unchanged at 25 degrees C, and the cross-linking is completed within 300 s at 90 degrees C. The chemical force probe atomic force microscope (AFM) technology has successfully demonstrated that catechol groups are the main source of supramolecular interaction in mussel-inspired polymers. The molecular simulation results show that due to the addition of catechol groups, the hydrogen bond interactions within the mussel-inspired polymers molecules are enhanced. And the additional hydrogen bonds formed are more stable at high temperature. The mussel-inspired delayed crosslinking gel fracturing fluid, which is formed by mussel-inspired polymers containing many catechol groups and organic zirconium delayed crosslinkers, can effectively balance the contradiction between the demand for fracturing fluid of "drag reduction in a wellbore, temperature, and shear resistance in reservoir" in the development of ultra-deep oil and gas fracturing. image