关键词: 页岩, 天然裂缝, 多簇压裂, 三维地质模型, 缝网压裂体积

Abstract: Traditional simulations of shale fracture propagation are mostly limited to two-dimensional models,and do not consider the mechanism of multi-fracture synchronous competitive propagation.Construction schemes for fracturing are mostly based on statistical analysis and field experience,which cannot effectively screen out the influence parameters of strong sensitivity in complex fracture network fracturing effects.To address this issue,a numerical model of fractured geomechanics in three-dimensional space is developed using the actual reservoir of W204H well area in the Weiyuan Block as a case study.The model takes into account the synchronous competitive propagation of fractures in multi-cluster fracturing and analyzes the impact of in-situ stress on construction parameters.Furthermore,the model quantitatively studies the influence of in-situ stress difference,cementing strength of natural fractures,perforation parameters,and fracturing fluid discharge on the volume of complex fracture networks.The results indicate that a higher in-situ stress difference leads to a lower activation probability of natural fractures and a less complex fracture network.Additionally,a lower cementation strength of natural fractures results in easier activation and capture of hydraulic fractures.When the cementation strength is less than that of the rock matrix,hydraulic fractures will penetrate natural fractures and propagate along the fracture height.Furthermore,a higher perforation combination density results in a smaller perforation pressure drop and a weaker ability to alleviate inter-cluster stress interference.The hydraulic fracture is more likely to propagate along natural fractures with an increase in the injection rate of fracturing fluid.To ensure the uniform propagation of multiple clusters when controlling dense perforation clusters,it is recommended to use large discharge and high viscosity fracturing fluid.This study provides a theoretical basis for the optimal design of volume fracturing in fractured shale reservoirs.

Key words: shale, natural fractures, multi-cluster fracturing, three-dimensional geological model, volume of fracturing network