Considering modern drilling technology,the feasible types,characteristics and developing background of underground closed loop drilling system have beed analyzed synthetically in this paper.

• 根据现代钻井工程技术的发展规律，综述了井下闭环钻井系统的可行方案、主要特征及技术发展背景，给出了井下闭环钻井系统的分类和适用范围。