| 摘要 |
This invention relates to centralizers for use in maintaining a tubular member such a conductor or string in a substantially co-axial arrangement within a bore, for example a platform guide or an outer tubular member or conductor. In particular, this invention relates to a centralizer for use in an oil or gas-drilling or production installation. A centralizer (1) for centralising a tubular member (5) within a bore (7) comprises a main body (2) connectable around a tubular member to be centralised, the main body defining a longitudinal axis (4) of the centralizer, and a plurality of longitudinally extending abutments (18) spaced apart around the main body (2) that extend radially outwards from the main body to abut the bore. At least one of the abutments has an adjustment mechanism (3, 34, 36, 42) for making a radially adjustable abutting contact with the bore. This mechanism comprises a radially movable outer blade (34), a longitudinally movable wedging member (36) located between the outer blade and the main body (2) for moving the blade radially into the abutting contact, at least one guiding mount (3) for guiding the radial movement of the blade, and at least one longitudinally extending ramp surface (42) that is inclined with respect to the axis (4). The outer blade (34) is constrained to move in a substantially radial direction by the at least one guiding mount. The wedging member (36) is constrained between the outer blade and the main body (2) to move in a substantially longitudinal direction, The wedging member and the at least one ramp surface are configured to engage with one another such that as the wedging member moves longitudinally, the wedging member causes the outer blade to move radially. The arrangement of the wedging member and the outer blade is such that when the longitudinal axis (4) is substantially vertical, the weight of the wedging member (36) automatically causes the wedging member to drop, thereby moving the outer blade (34) in the radially outwards direction. |
