Sand-injected fracturing technology has been developed for tight oil reservoirs to increase fracture complexity by alternately injecting "slippery water + gel solution" to vary viscosity.
Based on an integrated variable-viscosity fracturing process, an alternating mixed fracturing mode is employed, primarily using low-viscosity slickwater supplemented by multiple high-viscosity plug segments. The objective is to form a complex fracture network of primary and secondary fractures, effectively carry sand, reduce damage, and save costs: Low-viscosity fluids primarily open horizontal fractures, fracture the reservoir to create complex fractures, while minimizing damage, achieving true cost reduction and efficiency improvement. High-viscosity fluids penetrate high stress differentials, create high-angle fractures, have stronger interlayer penetration capability, and expand the affected area. High-viscosity fluids are alternately injected with low-viscosity fluids: Phased high-viscosity injection facilitates interlayer breakthrough, fully modifies the sand body, and ensures high sand ratio sand injection, forming effective sand-filled modification to guarantee subsequent fracture flow capacity.
Slippery water is used to create complex joints, and high sand content is used to ensure sand transport, while further ensuring that cracks break through and extend to fill the joints.
