GB619344A - Improvements relating to casing head equipment for boreholes or wells - Google Patents

Abstract

619,344. Boreholes or wells. SEAMARK, L. M. C. Dec. 3, 1946, No. 35819. [Class 85] Casing head equipment for boreholes or wells comprises a cylinder containing an annular piston within which is a massive elastic sleeve of rubber or the like mounted in upper and lower end rings, and means for applying hydraulic pressure on the piston to act through the upper end ring to apply axial compression and inward contraction to the elastic sleeve to cause the latter to engage a casing tube, drill stem or the like. A cylinder 1, bolted to the well-head flange 6, contains an annular piston 11, within which is a massive rubber &c. sleeve 20, the bore of the sleeve preferably tapering from each end ; the upper end of the sleeve 20 may be of relatively hard rubber, the middle section 21 of medium hard rubber, and the lower end of softer rubber. The upper end of the sleeve is held in an end ring 22 which is secured within the upper end of the piston by a bayonet joint 24 or the equivalent, a locking member securing the joint ; the lower end of the sleeve is held in an end ring 32 with a depending sleeve 34 which extends through a hard steel bush 36 and may be secured to the cylinder 1 by set-screws 58. Each end ring has passages 40, normally closed by plugs 39, to permit escape of air while securing the sleeve to the end rings, or for connection to a source of pressure to detach the sleeve. The upper end ring carries a flanged sleeve 43 to which a further casing head equipment may be attached. Passages 18, with an air bleeder valve 71, permit connection of the cylinder to a hydraulic accumulator &c., whereby to depress the piston and cause inward contraction of the sleeve 20 around a casing tube, drill stem &c. Studs 49, threaded to the cylinder, pass through a ring 47 threaded to the piston to limit upward movement thereof, or to hold the piston when the fluid pressure thereon is released ; set screws 54, threaded through the ring 47, contact the end of the cylinder to limit downward movement of the piston. A skirt 55 of rubber &c. is attached to the ring 47 and cylinder 1 by beadings 56 and prevents entry of mud &c. A passage 61, in the lower end of the cylinder, permits escape of air from below the piston. For use with small casing tubes, drill stems &c., the upper end ring is replaced by a liner extending through the piston and provided with a grooved internal flange in which the upper end of the sleeve 20 is received ; the lower end ring is modified accordingly to permit the liner to pass over its upper end. To facilitate dismantling &c., the piston may be held in its upper position by means of a slotted member 74, Fig. 4, secured to the ring 47 and adapted to be locked to the cylinder 1 by a bolt 75.