Dynamic Analysis Method and Production Prediction of Oil-Water Two-Phase Flow in Multistage Fracturing Horizontal Wells of Shale Oil

This study addresses key challenges in shale oil reservoir development using multistage fractured horizontal wells, where complex oil-water two-phase flow mechanisms limit the accuracy of conventional single-phase flow models in interpreting reservoir parameters and predicting production. A mathematical model for oil-water two-phase flow was established, incorporating the time-varying effects of water saturation and relative permeability. Pseudo-pressure and pseudo-time functions were introduced to linearize the governing partial differential equations. A semianalytical solution was derived to effectively characterize the complex two-phase flow behavior within the fracture-stimulated region. Based on type-curve analysis and history matching, an inversion workflow was proposed to determine key parameters, including fracture half-length and matrix permeability, and to predict dynamic production. Applied to Well Zhenye 1 in the Subei Basin, the productivity type curves clearly exhibit three flow regimes: linear flow, transition flow, and boundary-dominated flow. The inverted parameters align well with actual reservoir conditions, enabling high-accuracy production forecasts with an average parameter inversion error of less than 10%. This approach significantly reduces reliance on high-cost monitoring technologies and provides a practical, economical solution to support the efficient development of shale oil reservoirs.