Practice and Understanding of Ultra-Deep Shale Fracturing in Wujiaping Formation, Hongxing Area

The Wujiaping Formation shale in the Hongxing area is characterized by high carbonate content, high compressive strength, large stress differences, and development of bedding fractures. During fracturing, challenges such as high treatment pressure, narrow pressure windows, difficult proppant placement, difficulties in creating complex fractures, and severe proppant crushing and embedment under a high closure pressure are encountered. To address these problems, multiple rounds of process optimization were carried out. A combined technique of “deep penetration + prepad acid” was adopted, reducing the shale breakdown pressure by more than 5 MPa. High flow rate and alternating viscosity were employed, and microseismic monitoring indicated a 10.5% increase in fracture network complexity. A stimulation concept centered on “micro-fine proppant” dominated by silt was implemented, further expanding the propped area, and a fracturing technology system with the core principles of “reducing breakdown pressure, promoting fracture network complexity, and enhancing conductivity” was established. Field application in X-9HF with a maximum burial depth of 4 855.40 m achieved test production of 25.72×10⁴ m³/d, marking a breakthrough in ultra-deep shale gas exploration and adding over 100 billion cubic meters of proven reserves. The breakthrough in the Wujiaping Formation of Hongxing area provides a theoretical basis and technical reference for the exploration and development of other deep and ultra-deep shale gas reservoirs.