Unlike the vertical well, wellbore stability of the directional well varies from changes of deviation angle and azimuth. Therefore, the research on wellbore stability of the directional well will encounter enormous opportunity and challenge. 定向井与直井不同,定向井井壁稳定性随井斜角和相对方位角的变化而不同,因此,研究定向井井壁稳定将会遇到很大的机遇和挑战。