Fractures Propagation Feature of Multi-Cluster Fracturing on Deep Laminated Shale Oil Reservoir

Abstract In order to improve the production efficiency of oil and gas in the Sichuan Basin, it is necessary to study the propagation behavior of hydraulic fractures in the deep laminated continental shale oil reservoir. This study used the cohesive zone method to establish a numerical model for multi-fracture propagation in deep laminated shale oil reservoirs. Parameters such as cluster spacing and pump rate injection mode were taken into account. Through analysis of pore pressure and fracture width data, the feature of multi-fracture propagation in multi-cluster fracturing is revealed. The simulation results demonstrated that smaller cluster spacing exacerbates the uneven distribution of fracturing fluid flow between clusters, leading to increased competition and propagation of inter-cluster fractures, most transverse fractures were unable to fully propagate. Moreover, when the pump rate is low, lamina are easily activated. With pump rate increasing, hydraulic fractures tend to branch along microfractures surrounding the lamina, activating multiple layers. In the deep laminated continental shale reservoir, 8m cluster spacing and faster liquid injection rate are recommended as it effectively increase the probability of the main fracture penetrating the interlayer and effectively stimulate reservoir.