A new generation of fracture-controlled fracturing technology in Weiyuan Shale Gas Field of the Sichuan Basin

The Lower Silurian Longmaxi Formation shales in the Weiyuan area of the Sichuan Basin are generally characterized by high horizontal stress difference and strong heterogeneity. The early fracturing technologies, mainly formed with reference to the practices in the North America, are insufficient for simple hydraulic fracture networks and great varying postfrac effects. In order to improve the adaptability and rationality of the key parameters of fracture-controlled fracturing technology in the Weiyuan Shale Gas Field, a new generation of shale fracture-controlled fracturing technology, which pursues primary fractures instead of fracture networks, optimizes temporary plugging rather than displacement and replaces ceramsites with silts, is formed according to the fracturing design concept of saturated coverage and whole-domain support, combined with the numerical simulation of temporary plugging fracturing and the evaluation of proppant transportation. The following results are obtained. First, moderately reducing the cluster spacing in the section and replacing the earlier imperfect fracture network system with a denser main fracture can ensure the sufficient coverage of the reservoir by fractures. Second, the optimization of temporary plugging timing and dosage can improve the uniform fracture opening degree under the condition of multi-cluster fracturing, and it realizes higher accuracy and economy than simply increasing fracturing displacement. Third, the parameter combination of increasing silt proportion + enhancing proppant usage can achieve effective support of fractures at all levels. In conclusion, the technology has been applied practically more than 100 well times in Weiyuan shale, whose tested average production per kilometer is 7.2% higher, calculated average EUR is 4.3% higher, casing deformation rate is 28.7% lower and comprehensive fracturing operation cost is over 12% lower than the value before the application of the technology. What's more, this technology can effectively improve the utilization of shale gas reserves, and provide strong support for cost reduction and efficiency improvement of fracturing in Weiyuan Shale Gas Field, while providing technical guidance for the fine optimization of key parameters of shale gas fracturing in the southern Sichuan Basin. © 2023 Natural Gas Industry Journal Agency. All rights reserved.