裂缝面及井眼附近的应力分析

从力学角度出发,建立了川西致密气层井眼、裂缝面及地层的有限元模型,应用ANSYS软件仿真模拟了裂缝面与水平面夹角的变化引起裂缝面上及井眼附近的应力变化。重点研究了水平裂缝面上及井眼附近的主应力和等效应力的应力等值线变化规律。随着地层裂缝倾角的增加,裂缝面上井眼附近的最大等效应力逐渐转移到井眼椭圆截面的短轴两端附近。研究结果对进一步研究井眼稳定、井壁崩落方向或裂缝面上的应力敏感性具有指导意义。

STRESS ANALYSIS ON FRACTURE AND NEAR WELLBORE

Based on the mechanics theory, the paper presented the FEM model of wellbore, fracture and formation for tight gas sandstone reservoirs in western Sichuan basin, and simulating the angle change between the fracture and horizontal plane resulting in the stress change on the fracture and near wellbore.This paper mainly studied the change principle of the principalstresses and equivalent stresses on the horizontal plane fracture and near the wellbore. With the increasing of the incline angle of formation fracture, the maximum equivalent stresses near the wellbore on the fracture gradually transferred to the two ends of the borehole ellipse cross-section shorter axis. It is a guidance meaning to further study the borehole stability, the breakout direction of borehole wall or the stress sensitive on the fracture.