滑溜水压裂主裂缝内支撑剂输送规律实验及数值模拟

滑溜水压裂时通过泵送大排量压裂液在储层中形成主裂缝为主干的裂缝网络，主裂缝内支撑剂的铺置状况直接影响油气井的产能。采用自主设计的大型可视化平板裂缝装置来研究大排量泵送时主裂缝内支撑剂的输送规律，建立了相应的数值模型模拟了砂堤在不同时刻的铺置形态，并分析了湍流对支撑剂铺置的影响规律，为滑溜水压裂时主裂缝内支撑剂的有效铺置提供一定的理论指导。研究表明，滑溜水压裂时支撑剂在主裂缝内的铺置规律与小排量压裂时不同:支撑剂首先在主裂缝入口处形成一个较低的砂堤，而在距入口较远处形成一个较高的砂堤，之后才一层一层周期性的覆盖在两处砂堤之上，直到达到最终的平衡高度；大排量压裂时易引起湍流，将主裂缝进口端暂时沉降的支撑剂重新卷入裂缝深处，形成类似“卷云状”的沉降结构；数值模拟与物理实验模拟得到的支撑剂铺置结果相似，证明了研究的数值模型具有一定的实用性。

Experiment and numerical simulation on transportation laws of proppant in major fracture during slick water fracturing

When slick water fracturing is carried out, a fracture network with the major fracture as the trunk is formed in the reservoir by pumping fracturing fuid at high fow rate, so the laying situations of proppant in the major fracture has direct effect on the productivity of oil and gas wells. In this paper, the independently designed large visual plate fracturing device was used to investigate the transportation laws of proppant in the major fracture in the process of high rate pumping. The corresponding numerical model was established to simulate the laying form of sand bank in different time. And the infuential laws of turbulence on the laying form of proppant were analyzed. It provides the theoretical guide for the effective laying of proppant in the major fracturing in the process of slick water fracturing. It is indicated that the laying law of proppant in the major fracture during the slick water fracturing is different from that during low fow rate fracturing. The proppant frstly generates a lower sand bank at the entrance of the major fracture and a higher sand bank farther from the entrance, and then covers both sand banks periodically layer after layer until the balance height is ultimatelyreached. In the case of high fow rate fracturing, turbulence occurs easily and take the proppant which is temporarily settled at the entrance of the major fracture into the deep part of the fracture again. And consequently the settlement structure of approximate cirrus shape is formed. The numerically simulated laying form of proppant is consistent with the result of physical experiment. It is proved that the numerical model established is practical.