Triaxial fracturing modeling experiments were carried out on whole diameter shale cores from different layers of Shahejie Formation in the Dongpu sag, Bohai Bay Basin to find out the vertical propagation shapes of hydraulic fractures in different reservoirs. A numerical simulation method of inserting global cohesive elements was adopted to build a pseudo-three-dimension fracture propagation model for multiple shale oil reservoirs considering interface strength, perforation location, and pump rate to research the features of hydraulic fracture (HF) penetrating through layers. The hydraulic fracture propagates in a cross pattern in tight sandstone layers, in a straight line in sandstone layers with natural fractures, forms ladder fracture in shale layers with beddings. The hydraulic fracture propagates in a stripe shape vertically in both sandstone and shale layers, but it spreads in the plane in shale layers after connecting beddings. Restricted by beddings, the hydraulic fractures in shale layers are smaller in height than those in sandstone layers. When a sandstone layer and a shale layer are fractured at the same time, the fracture extends the most in height after the two layers are connected. Perforating at positions where the sandstone-shale interface is higher in strength and increasing the pumping rate can enhance the fracture height, thus achieving the goal of increasing the production by cross-layer fracturing in multiple shale oil layers.

在渤海湾盆地东圃凹陷沙河街组不同层的全径页岩岩心上进行了三轴压裂建模实验，以求得不同储层中水力压裂的垂直传播形态。采用数值模拟的方法，通过考虑界面强度，射孔位置和抽速等因素，建立了多页岩油藏拟三维三维裂缝扩展模型，研究了贯穿层的水力压裂特征。 。水力压裂在致密的砂岩层中以十字形传播，在自然压裂的砂岩层中以直线传播，在带顺层的页岩层中形成阶梯形裂缝。水力压裂在砂岩和页岩层中均呈条状垂直传播，但在连接顺层后在页岩层中沿平面扩展。受地层限制，页岩层的水力压裂高度小于砂岩层的水压压裂高度。当砂岩层和页岩层同时断裂时，在将两层连接之后，断裂在最大程度上扩展。在砂岩-页岩界面强度较高的位置打孔，提高抽速可以提高裂缝高度，从而达到在多个页岩油层中进行跨层压裂提高产量的目的。页岩层的水力压裂的高度小于砂岩层的水力压裂。当砂岩层和页岩层同时断裂时，在将两层连接之后，断裂在最大程度上扩展。在砂岩-页岩界面强度较高的位置打孔，提高抽速可以提高裂缝高度，从而达到在多个页岩油层中进行跨层压裂提高产量的目的。页岩层的水力压裂的高度小于砂岩层的水力压裂。当砂岩层和页岩层同时断裂时，在将两层连接之后，断裂在最大程度上扩展。在砂岩-页岩界面强度较高的位置打孔，提高抽速可以提高裂缝高度，从而达到在多个页岩油层中进行跨层压裂提高产量的目的。