Fracturing Technology for Permian Ultra-Deep Shale Gas in Well Tiebei 1 Sidetrack-HF in Northeastern Sichuan

Well Tiebei 1 Sidetrack-HF is a Permian ultra-deep shale gas horizontal well with a vertical depth exceeding 5 300 m. It is characterized by poorly developed natural fractures, a differential horizontal in-situ principal stress of 13.5–17.7 MPa, and multiple thin limestone interbeds developed vertically. Fracturing stimulation faces multiple challenges, including high treatment pressure, narrow fracture widths, difficulty in proppant placement, and limited vertical fracture propagation, etc. Based on core experiments, the mechanical and brittle characteristics of the Dalong Formation shale were evaluated. Combined with a geology-engineering integration model, the synergistic regulation laws of pad fluid flow rate, viscosity, and injection volume on vertical fracture propagation were analyzed, fracturing parameters for penetrating different sublayers were quantified, and proppant placement strategies for fractures with different scales were clarified. A fracturing technology system with the core principles of “fine and dense fracture layout + non-uniform aftereffect perforation + high-viscosity and high-flow-rate fracturing + multi-size proppant staged placement” was established. After application in Well Tiebei 1 Sidetrack-HF, high-yield gas flow was achieved, marking a breakthrough in Permian ultra-deep shale gas exploration. The research results provide technical support for the efficient development and mobilization of ultra-deep shale gas resources in northeastern Sichuan.