GB998037A - Well operations - Google Patents

Abstract

998,037. Wells &c. CAMERON IRON WORKS INC. July 24, 1963 [May 28, 1963], No 1741/65. Divided out of 998,036. Heading E1F. Casing 36 is hung from a seat 31 and sealed in a wellhead 25 by severing the casing between the seat and the adjacent casing collar 37, removing the severed upper portion of the casing, lowering a slip assembly 42 onto the seat, straining the casing and releasing it to cause the assembly to suspend the casing, and forming a seal between the wellhead and the casing. The method is particularly applicable to the completion of sub-aqueous wellheads in which the casing has become stuck as it is lowered into the well. A cutter 38 is lowered on a pipe 41 through the casing to the level of the wellhead, the casing being enclosed by a marine conductor (not shown) and blowout preventers 28. The upper portion of the casing is severed and removed, and the slip assembly is lowered onto the seat by means of a tool 43 which is then removed. The pipe 41 which is connected to the casing by the cutter 38 is raised to tension the casing to permit the slips 51 to grip the casing. The cutter 38 and pipe 41 are removed, and cutters 52 are lowered into the wellhead to cut the casing to its correct length, a spacer 55 being used. After the cutters 52 have been removed a seal assembly 57 (Fig. 9) is lowered into the wellhead on a tool 58. The seal assembly is rotated to anchor it to the slip assembly by hooks 62. Further rotation of the tool 58 causes an intermediate part 67 to screw onto a lower part 64 of the assembly to force a seal 71 to engage the casing. Continued rotation of the tool 58 shears a pin 80 to permit an upper part 66 to rotate relative to the intermediate part to press a seal 74 against the wellhead and set slips 78. The tool 58 is released, and should further drilling of the well take place a seat 81 for further casing forms a guide for the drill. In a modification of the seal assembly (Fig. 13, not shown) the slips are free to move under gravity and are placed below the seal 74, the shear pin being dispensed with.