缝内多级暂堵是提高缝内净压力，激活侧向分支缝，增大侧向改造带宽，提升层内油气动用程度的有效手段之一。研究缝内多级暂堵转向规律对指导优化暂堵方案至关重要，其难点是建立缝内暂堵模拟方法。针对裂缝性超低渗储层，基于等效黏度方法，建立了缝内多级暂堵数值模型，系统研究了逼近角、应力差、暂堵次数对分支缝开启的影响规律，研究结果表明：当水平应力差≥5 MPa且逼近角较大（≥60°）时，水力裂缝倾向于穿过天然裂缝，沿当前方向扩展，无法激活天然裂缝；水平应力差≤5 MPa时且逼近角较小（≤30°）时，水力裂缝遇到天然裂缝后能够开启钝角分支；缝内初次暂堵能够有效开启高逼近角下一级分支缝，缝内二次暂堵能够开启二级分支缝；采用缝内多级暂堵能够提高单井最高日产油量至2倍，平均日产油量提升至3倍。本文研究成果对缝内多级暂堵压裂设计奠定了模型和方法基础。

In-fracture Multistage plugging is one of the effective means to increase the in-fracture net pressure, activate lateral branch fractures, increase the lateral reconstruction bandwidth, and improve the degree of oil and gas utilization in the reservoir. The investigation of diversion pattern during multistage plugging is of great value for the optimization of multistage temporary plugging in fractures, a numerical model of multistage temporary plugging in fractures was established for the ultra-low permeability fractured reservoir, and the influence rule of approaching angle, stress difference and number of temporary plugging on the opening of branch fractures was studied. The research results show as follows When the horizontal stress difference is beyond 5 MPa, the hydraulic fracture will cross the natural fracture directly at the high approximation angle (≥60°), and it cannot be activated effectively. When the horizontal stress difference is less than 5 MPa and the low approximation Angle (≤ 30°), the hydraulic fracture can open the obtuse branch after encountering the natural fracture. The initial plugging can effectively open the next level of branch joints with high approximation angles, and the secondary plugging can open the secondary branch joints. Using multi-stage temporary plugging in fractures can increase the maximum daily oil production of a single well to two times and the average daily oil production to four times. This work provides the model and method for the design of in-fracture multistage temporary plugging fracturing.