Selective high-molecular fracture catalyst as well as preparation method and application thereof

The invention discloses a selective high-molecular fracture catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: filling water into a reaction kettle and increasing the temperature to 50 DEG C; adding an organic phosphate chelating agent in to the reaction kettle and reacting for 1 h; adding a reducing agent and reacting for 30 min; finally, adding a boron removal catalyst, increasing the reaction temperature to 50 to 90 DEG C, and reacting for 3 h. The selective high-molecular fracture catalyst provided by the invention is mainly applied to gel breakage of fracturing fluid in an oil field, and the usage amount is 0.05 to 0.1% of the total mass of the fracturing fluid. The selective high-molecular fracture catalyst has the beneficial effects that gel can be broken radically, the price is reasonable, and the catalyst does not have corrosivity and is free from influence of a great amount of co-existence salt; all ingredients contained in the product supplement one another, the boron removal catalyst lowers the activation energy of boron to ensure that the fracturing fluid is unstable in boron cross-linking performance and is degraded unceasingly so as to achieve the effects of hydration and gel breakage at last, the reducing agent can lower activation energy and serves as a low-temperature activating agent to prevent oxygen corrosion, and the organic phosphate chelating agent can prevent scaled and treated water from being compatible with follow-up water.