A New Well-Testing Method for Pumping-Shutdown Data of Multi-Fractured Horizontal Wells: A Case Study from the Sichuan Shale Gas Basin

In southern Sichuan’s deep shale gas development, multi-stage fractured horizontal wells are commonly used. Evaluating fracturing results is challenging due to complex fracture networks. This study classifies fracture systems into four types: single-wing, bi-wing, branched, and serial fractures. A discrete fracture model (DFM) combined with matrix-fracture flow is used to establish a single-stage well testing interpretation model. To address multi-solution issues in well testing, an equivalent fracture network model based on a trilinear flow model is proposed, adjusting crossflow coefficients and the fracture network volume ratio. The study finds significant differences in the pressure derivative dip and the second linear flow stage onset with changes in these parameters. Sensitivity analysis shows that inner zone permeability affects the early and middle stages of the well testing curve. Using shut-in pressure data, a numerical well testing model is applied, with results showing a fracture zone permeability of 0.95 mD, a fracture half-length of 87 m, and fracture network volume ratio of 5%. This research provides guidance for evaluating fracturing effects.