To evaluate the fracturing effect and dynamic change process after volume fracturing with vertical wells in low permeability oil reservoirs, an oil-water two-phase flow model and a well model are built. On this basis, an evaluation method of fracturing effect based on production data and fracturing fluid backflow data is established, and the method is used to analyze some field cases. The vicinity area of main fracture after fracturing is divided into different stimulated regions. The permeability and area of different regions are used to characterize the stimulation strength and scale of the fracture network. The conductivity of stimulated region is defined as the product of the permeability and area of the stimulated region. Through parameter sensitivity analysis, it is found that half-length of the fracture and the permeability of the core area mainly affect the flow law near the well, that is, the early stage of production; while matrix permeability mainly affects the flow law at the far end of the fracture. Taking a typical old well in Changqing Oilfield as an example, the fracturing effect and its changes after two rounds of volume fracturing in this well are evaluated. It is found that with the increase of production time after the first volume fracturing, the permeability and conductivity of stimulated area gradually decreased, and the fracturing effect gradually decreased until disappeared; after the second volume fracturing, the permeability and conductivity of stimulated area increased significantly again.

为了评价低渗透油藏垂直井体积压裂后的压裂效果和动态变化过程，建立了油水两相流模型和油井模型。在此基础上，建立了基于生产数据和压裂液回流数据的压裂效果评价方法，并用于分析一些现场案例。压裂后的主裂缝附近区域分为不同的受激区域。不同区域的渗透率和面积用于表征裂缝网络的增产强度和规模。受激区域的电导率定义为受激区域的磁导率和面积的乘积。通过参数敏感性分析，发现裂缝的一半长度和岩心区域的渗透率主要影响井附近的流动规律，即生产的早期阶段。而基质渗透率主要影响裂缝远端的流动规律。以长庆油田一口典型老井为例，评价了该井两轮体积压裂后的压裂效果及其变化。发现随着第一次体积压裂后生产时间的增加，受压区的渗透率和电导率逐渐降低，压裂效果逐渐降低直至消失。第二次体积压裂后，受激区域的渗透率和电导率再次显着增加。而基质渗透率主要影响裂缝远端的流动规律。以长庆油田一口典型老井为例，评价了该井两轮体积压裂后的压裂效果及其变化。发现随着第一次体积压裂后生产时间的增加，受压区的渗透率和电导率逐渐降低，压裂效果逐渐降低直至消失。第二次体积压裂后，受激区域的渗透率和电导率再次显着增加。而基质渗透率主要影响裂缝远端的流动规律。以长庆油田一口典型老井为例，评价了该井两轮体积压裂后的压裂效果及其变化。发现随着第一次体积压裂后生产时间的增加，受压区的渗透率和电导率逐渐降低，压裂效果逐渐降低直至消失。第二次体积压裂后，受激区域的渗透率和电导率再次显着增加。发现随着第一次体积压裂后生产时间的增加，受压区的渗透率和电导率逐渐降低，压裂效果逐渐降低直至消失。第二次体积压裂后，受激区域的渗透率和电导率再次显着增加。发现随着第一次体积压裂后生产时间的增加，受压区的渗透率和电导率逐渐降低，压裂效果逐渐降低直至消失。第二次体积压裂后，受激区域的渗透率和电导率再次显着增加。