Abstract: With the rapid development in recent years, ultra low permeability oil and gas resources, the main controlling factors of the elastic recovery stage has attracted wide attention. In order to study the factors affecting oil recovery in ultralow permeability reservoir during elastic exploitation stage, the permeability, viscosity, failure pressure and failure radius are combined into 4 factors and 3 levels orthogonal experiment, through laboratory experiments, the order of influence degree is as follows: failure pressure difference>permeability>failure radius>crude oil viscosity. Combined with the scanning electron microscope images, it is found that the degree of recovery is related to the stress sensitivity and the startup pressure gradient, besides the initial elastic energy. In addition, the starting pressure gradient mathematical models of permeability, fluidity, fluiditypressure difference are compared and analyzed. Through the error analysis of numerical simulation and experimental data, the model which is closer to the real situation is chosen as the pressure difference mobility model.

Key words: Ultra-low permeability reservoir, Elastic mining, Orthogonal test, Start pressure gradient, Numerical simulation

摘要： 随着近年来我国超低渗油气资源的快速开发，其弹性开采阶段的主控因素已引起广泛关注。为研究超低渗储层弹性开采阶段影响采收率的因素，将渗透率、黏度、衰竭压差及衰竭半径组合为4因素3水平正交实验，通过室内实验得出影响采出程度的排序为：衰竭压差>渗透率>衰竭半径>黏度。结合扫描电镜图像，分析采出程度除了与自身的初始弹性能有关外，还与应力敏感性及启动压力梯度有关。此外，对比分析渗透率、流度、流度压差3种模式的启动压力梯度模型，通过数值模拟与实验数据的误差分析，优选出更趋近真实情况的模型为流度-压差模型

关键词: 超低渗储层, 弹性开采, 正交实验, 启动压力梯度, 数值模拟