Cross-layer propagation law of hydraulic fractures in continental shale reservoirs with sandstone-shale interaction
Due to the interbedded development of sandstone-shale in continental shale reservoirs,there are significant differences in rock mechanical properties and ground stress of the layers,making it difficult for hydraulic fractures to cross-layer propagation,resulting in poor fracturing stimulation effects.This article adopted the finite element+cohesive force element method to establish a three-dimensional numerical model of hydraulic fracture cross-layer propagation.The accuracy of the model was verified through analytical solution and indoor experiments,and single factor and range analysis methods were used to conduct case study,fully revealing the effect law of geological and engineering factors on hydraulic fracture cross-layer propagation.The research results indicate that high interlayer stress difference,high interlayer tensile strength difference,low interlayer elastic modulus difference and high interlayer thickness are not conductive to the cross-layer propagation of hydraulic fractures,and increasing the construction displacement and fracturing fluid viscosity can effectively improve the cross-layer propagation ability of hydraulic fractures.The order of the effect degree of each factor is as follows:interlayer stress difference,interlayer elastic modulus differences,interlayer tensile strength difference,interlayer thickness,injection displacement and fracturing fluid viscosity.The above model was used to conduct construction parameter design of example wells.It is recommended that the single cluster injection displacement should be no less than 2.5 m3/min,and the fracturing viscosity during preliminary construction should be no less than 20 mPa·s.The on-site application effect is good,verifying the engineering application value of the model.
万方数据
维普
