APPARATUS FOR USE IN DRILLING OPERATIONS

摘要

A method of facilitating fluid circulation may be utilised during a drilling operation in which drilling fluid is circulated downwardly through a small diameter drill support, such as coiled tubing (22), and upwardly through an annulus (44) between a lined bore wall (38) and the drill support (22). The method comprises providing a sleeve (48) between the bore wall (38) and the drill support (22) to reduce the annulus flow area to facilitate maintaining the drilling fluid flow speed in the annulus at a level sufficient to maintain entrainment of drilling cuttings. Further provided is a method of protecting a well head tree and safety valve from erosion by drilling fluid by hanging a protection sleeve above the tree (or safety valve) and sealing above and below the tree (or safety valve).