Abstract:
The Tiebei 1 side-track HF well is a Permian ultra-deep shale gas horizontal well with a vertical depth exceeding 5,300 m. Natural fractures are generally poorly developed, with the difference between the two horizontal principal stresses ranging from 13.5 to 17.7 MPa, and multiple thin limestone interbeds are vertically developed. Fracturing stimulation faces multiple challenges, including high treating pressure, narrow fracture width, difficulty in proppant placement, and limited vertical fracture propagation. Based on core experiments, the mechanical properties and brittleness of the Dalong Formation shale were evaluated. Combined with a geological-engineering integrated model, the synergistic regulation law of pad fluid displacement, viscosity, and injection volume on vertical fracture propagation was revealed, the fracturing parameters for penetrating different sub-layers were quantified, and the proppant placement methods for fractures of different scales were clarified. Consequently, a fracturing technology system was established, centering on “densely spaced fractures, non-uniform after-effect perforation, high-viscosity and high-rate fracture creation, and multi-size proppant staged placement.” After applying this fracturing technology, the Tiebei 1 side-track HF well obtained high-yield gas flow, achieving a breakthrough in the exploration of Permian ultra-deep shale gas. These research results provide technical support for the efficient development and production of ultra-deep shale gas resources in the northeastern Sichuan Basin.