GB622341A - Improvements in or relating to rotary jars for use in well drilling operations - Google Patents

Abstract

622,341. Well-drilling jars. BOYD, F. C., and BUTLER, W. O. March 12, 1947, No. 6892. Convention date, March 18, 1946. [Class 85] Relates to jars for loosening stuck drills &c. in well-drilling and comprises a mandrel mounted in a housing for relative longitudinal and rotational movement, and restraining means adapted to hold said mandrel and housing against relative rotation while torsion is applied, the restraining means being then freed and the torsion causing relative rotation to cause a hammer member on one of the parts to strike a blow in a rotary direction against impact means on the other part. In Figs. 1 and 6, a housing 18 secured to drill pipe &c. contains a mandrel 20 connected to the stuck drill &c. and has a lug 21 adapted to engage a flute 45 in the mandrel to hold the parts while torsion is applied to the drill pipe as by the rotary table; the housing is then raised to free the lug 21 which, under the torsional effect, rotates to strike an impact member 22 longitudinal of the mandrel. To facilitate assembly, the upper end of the mandrel is initially provided with a flute similar to the flute 45, and the housing 18 is formed in two parts 18a, 18b; the mandrel is inserted in the part 18a, the flute in the upper end of the mandrel is filled with welding metal and said upper end is threaded to receive a guide collar 24 and wash pipe 41 with packer 39, and the parts 18a, 18b are welded at 23. Upward or downward blows may be effected through shoulders 31, 32 or 26, 28. In Figs. 8 and 9, the housing 58 has a lower end 58a with a reduced bore provided with steep internal threads 61 co-operating with threads 62 on the mandrel 74 which has a hexagonal part 75 slidable in a corresponding hexagonal bore in a sleeve 80 secured to the stuck drill etc.; the housing 58 and sleeve 80 have cam ends providing dogs 98, 99, which are engaged to hold the parts while torsion is built up in the drill pipe &c., the housing 58 then being raised to free the dogs 98, 99, when the torsion rotates the housing to cause housing end 58a to give a blow with a vertical component acting through mandrel head 66 and a horizontal component acting through threads 62. In Fig. 12, the mandrel 60 and housing 58 have a similar threaded connection 61, 62, but the mandrel is directly connected to the stuck drill &c., and carries a lock sleeve 80a slidable on splines 107 against resistance of a spring 108, the lock sleeve having an inclined dog 99a cooperating with an inclined dog 98a on the lower end of the housing 58; application of excessive torsion to the drill pipe is prevented by relative sliding movement of the dogs 98a, 99a.