Abstract: In response to the issue that there are certain differences in flow regime characteristics and curve morphology between the actual well test curves and theoretical curves of multi-stage fractured horizontal wells in tight sandstone gas reservoirs,a seepage model for multi-stage fractured horizontal wells was established.Theoretical well test curve charts were drawn to analyze the impact of fracture parameters on well test curves.Based on mine field examples, the characteristics of well test curves of multi-stage fractured horizontal wells in the tight gas reservoir of the Shaximiao Formation in the Tianfu Gasfield were analyzed.The study shows that Compared with the well test curves of traditional fractured horizontal wells,the early fracture bilinear or linear flow stage of multi-stage fractured horizontal wells is masked by the wellbore storage effect and skin effect.In the middle stage, only the characteristics of the radial flow stage are exhibited,and in the later stage,it transitions into the formation linear flow stage.The larger the fracture half-length and the more complex the fracture network,the more obvious the difference between the middle radial flow stage and the formation linear flow stage.The multi-stage fractured horizontal wells in the tight gas reservoir of the Shaximiao Formation in the Tianfu Gasfield are affected by the complex fracture network near the wellbore and the river channel boundaries.The flow regime can be divided into four stages:wellbore storage and skin reflection,radial flow,formation linear flow, and boundary reflection. This study provides a new approach for precise well test analysis of multi-stage fractured horizontal wells in tight sandstone gas reservoirs.

Key words: tight gas reservoir, sandstone, multi-stage fractured horizontal well, micro-fracture, well test curve characteristics, Shaximiao Formation, Tianfu Gasfield