| 摘要 |
<p>An axially-floating sub tool for use with a top drive provides for axial load compensation by means of positive pressure or vacuum. The sub tool comprises a cylindrical upper member coaxially disposed within a cylindrical housing, with an upper section of the upper member slidably disposed within an opening in the upper end of the housing. The upper member also has a middle section that slidably and sealingly engages the cylindrical bore of the housing, plus a longitudinally-splined lower section. A cylindrical lower member has a cylindrical bore including a longitudinally-splined upper interval, and carries a coaxial stinger sealed to and extending upward from an annular shoulder in a medial region of the lower-member bore. The lower member is connected to the lower end of the housing with the stinger slidingly and sealingly disposed within the bore of the upper member, and with the splines on the upper interval of the lower- member bore slidingly engaging the splines on the lower section of the upper member, thus defining an upper annular chamber above the middle section of the upper member, a middle annular chamber between the middle section of the upper member and the upper end of the lower member, and a lower annular chamber between the lower end of the upper member and the shoulder on the lower member. The middle and lower annular chambers are in fluid communication, with a regulator/check valve being provided to regulate the pressure in the middle and lower annular chambers. The sub tool may optionally incorporate a passive compensator assembly mounted over the housing.</p> |
