GB260140A - Improvements in or relating to well drilling apparatus - Google Patents

Abstract

260,140. Beazley, A. T., and Watson, N. O. Jan. 19, 1926. Wells; borehole apparatus.-In welldrilling apparatus the drilling means carries a sealing member which is normally out of engagement with the casing head and which upon upward movement contacts with the casing head to effect a seal; further sealing means may then be applied above the casing head. The well casing 1 has a valve 2 and is connected to the casing head 6 by stays 8. A breech block 9 is connected to the casing head by mutilated thread's and a nut 16 normally rests loosely on the breech block ; packing 11 is provided below the breech block. The drive stem 17 is connected to the drill rods 20 by a nipple 19 and a sealing means 21, the latter comprising an enlargement 24 above which is a sealing part 25 adapted when raised to make a line-contact seal with the breech block, or the part 25 may be of yielding material such as lead. Above the part 25 are mutilated threads 26 for co-operation with the nut 16. In the nipple 19 is a ball valve 30 which closes the passage through the drill rods when pressure is encountered in the well. The drill rods are then raised so that the part 25 seals off the casing head 6 while the pressure is relieved through a valve 5 ; the seal may be assisted by applying a split ring 28 of lead &c. above the breech block. If high pressures are encountered, the nut 16 is engaged with the threads 26 to hold the drill rods and compress the ring 28 ; the drive stem 17 is then removed and a T-piece 30<c> attached, the T-piece having a screw 31 for opening the ball valve 30 to assist in relieving the pressure.