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

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