Two-phase pressure transient analysis for multi-stage fractured horizontal well in shale gas reservoirs

Most researches on shale gas production and pressure transient analysis placed more emphasis on single-phase flow, the two-phase flow caused by flowback after hydrofracture in shale gas reservoirs does not attract much attention. This paper presents a two-phase pressure transient analysis model of multi-stage fractured horizontal well with the consideration of wellbore storage, skin effect, two-phase saturation, hydraulic fractures parameters and desorption characteristics of shale gas reservoirs. Accurate solution to this flow model is obtained by the use of source function theory, Laplace transform, three-dimensional eigenvalue method and orthogonal transformation. Pseudo-pressure and pseudo-pressure derivative type curve is plotted by using the Stehfest algorithm. Seven different flow regimes have been identified and the effects of influence factors such as initial saturation, skin factor, absorption index, fracture stages, horizontal well lateral length and wellbore storage coefficient have also been discussed. The presents research could be used to interpret the pressure behavior more accurately and effectively of shale gas reservoirs.