GB326615A - Improvements in or relating to well drilling - Google Patents

Abstract

326,615. Trout, W. A., and Rasmussen, C. A. Jan. 25, 1929. Wells. - A blow-out preventer for wells comprises a member expanded by a fluid under pressure to seal the space between the outer well casing and the drill pipe, or an inner well casing, during insertion &c. of the latter, couplings on the drill-pipe or inner well casing automatically effecting deflation of the expansible member so as to permit the couplings to pass. In Fig. 1, the blow-out preventer, fixed above the casing head 12, comprises superposed inflatable packers 55, 85, 118, the packer 55 being for emergency use only, the packer 85 being flared at its lower end and a gas space 107 being provided between the packers 85, 118; the packer 55 has a cut-off valve 224 and an escape valve 51. Gas for controlling the device is taken either from the casing head through pipe 18 or from an auxiliary supply pipe 221; the gas supply is constantly open to the packer 85, while the space 107 and packer 118 may be exhausted through pipe 227. Excess gas passes to exhaust through valve 229. Gas supply and exhaust from the space 107 are controlled by valves 216, 226 respectively, and supply and exhaust from the packer 118 are controlled bv a valve 203. The valves 216, 226 are connected by a link 253 to a. pivoted lever 144; a further link 248 connects the lever 144 to the valve 203 through a lost-motion connection. The lever 144 has a spring-pressed slidable inner end 152 projecting into the blowout preventer and provided with pins 155 cooperating with cams 137 to withdraw the end 152. At the upper end of the device are pivoted spring- controlled levers 175 for centralizing the drill pipe &c., while a seating is also provided for slips 167. In use, as a drill pipe &c. 260 is inserted, a coupling 261 contacts the end 152 of the lever 144 and depresses the latter, thereby first, through link 253, closing the space 107 to supply and opening it to exhaust and afterwards closing the packer 118 to supply and opening it to exhaust. The coupling may then pass into the space 107, a spring 255 then return the lever 144 whereby supply to the space 107 and packer 108 is reopened. The packer 85, being open to the same pressure internally and at each end, then easily allows passage of the coupling 261. In a modification, Fig. 7, only two packers 310, 360 are provided, the inlet and exhaust pipes 301, 355 leading to and from the packers having check valves 449, 425, such valves having a flap 435 with a bleed port 436, as in Fig. 11. Valves 423, 450 control the supply and exhaust from the upper packer 360 and the intermediate space 334 respectively, the valves being connected by a link 460; the connection of the link 460 with the valve 450 is through a pin and slot 461, and springs 446, 463 tend to move the valves so as to open them to the pressure supply. The pressure supply may be through a pipe 279 from the well or from a hydraulic &c. pump through a pipe 420. One of the centralizing levers 401 is extended and connected through a slotted link 466 to the valves; a lever 337 within the intermediate space 334 is also connected through an external lever 340 and slotted link 470 to the valves, the lever 340 being normally held in mid-position by springs 371, 372. In use, when an inner casing &c. 480 is being inserted, the couplings 481 act through the lever 401 to operate the valves to open the packing 360 and space 334 to exhaust; if the casing &c. is being removed, the couplings act through the lever 337 to effect the same result. A modified form of centralizing means comprises a ring 504, Fig. 12, adjusted to the desired position by screws 510.