Online Mixing of Produced Water with Low Damage Hydraulic Fracturing Fluid System

Fracturing reservoir technology has become a powerful tool for low and ultra-low permeability reservoir reconstruction, and is an important and indispensable technical means for oil and gas exploration and development. In view of the shortage of water resources and the increasing of produced water in oilfield fracturing operation, it is urgent to study the use of oilfield produced water to prepare fracturing fluid, so as to solve the problem that the produced water can not form glue or the viscosity is low. Through improving the dissolving ability of thickener in produced water as the starting point, the idea of “removing interference factors” and “strengthening the function of thickener” was obtained by using the innovative ARIZ method. The modified guar gum was used as the thickener and the rigid salt-resistant and supramolecular side groups were introduced into the polymeric monomer combined with the characteristics of some reservoirs in Erian Oilfield. A formula system of produced water fracturing fluid suitable for erlian oilfield reservoir transformation is developed. When the temperature is less than 80 ℃, the technical indexes of the system meet the technical requirements of SY/T6736, effectively solve the winding effect of calcium and magnesium ions on polymer chain, and improve the quick solubility, thickening and heat resistance of polymer thickener. The application results in Erlian oilfield show that the viscosity of the base fluid prepared with produced water is close to or higher than that prepared with clear water, guar gum has good swelling ability in produced water, stable pressure during field construction, good sand carrying performance, and the productivity after pressure reaches the expected effect. The fracturing system has a broad application prospect.