关键词: 启动压力梯度, 低渗透油藏, 垂直裂缝, 质量守恒定律, 椭圆流法, 数学模型

Abstract: The wells with finite conductivity vertical fractures would be formed after fracture treatment in the low-permeability double-porosity reservoirs.Based on the Warren-Root model,the mathematical models for wells with finite conductivity vertical fractures in low-permeability reservoirs were developed using the mass conservation law and elliptical flow method,considering the influences of threshold pressure gradient.The equations for bottom pressure of vertical fractured wells could be achieved using the Laplace transformation.The analysis on the affecting factors of dynamic pressure indicated that the threshold pressure gradient had a remarkable influence on the typical curves of the low-permeability wells with vertical fractures.The curves of dimensionless pressure and pressure derivation climb up at the later stage.The curves get up earlier with the more increase of the threshold pressure gradient.A real build-up testing explanation example of a fractured well in low-permeability reservoir was given.

Key words: threshold pressure gradient, low-permeability reservoir, vertical fracture, mass conservation law, elliptical flow, method mathematical model