DEVICE TO REDUCE IMPACT LOADS APPLIED BY KELLY AND KELLY SUB TO WELL HEAD Russian patent published in 2007 - IPC E21B33/03 

FIELD: oil and gas well drilling and workover.

SUBSTANCE: device additionally comprises at least one protective bush 4, fastened to kelly sub 3 and formed of resilient material. The bush is split along bush length and has diameter equal to 1.1-1.2 diameters of kelly sub 3 clutch. Outer bush surface is provided with grooves having wedge-like cross-sections and adapted to receive fastening members 9. The fastening members are made as belts having wedge-like cross-sections. Fastening member ends define lock. Belt thickness is not more than groove 8 depth. Protective bush 1 of reel 2 located over preventer is made of resilient material and installed inside the reel 2 so that protective bush wear may be observed as difference between inner diameter of protective bush and inner diameters of metal inserted bushes. The inserted bushes have L-shaped cross-sections and arranged so that the first flanges thereof extend along end surface of protective bush and flange edge faces outwards. The other flanges of the inserted bushes are provided with fixing orifices uniformly distributed over surface generatrix and are located in resilient material of protective bush 1.

EFFECT: reduced impact loads acting on wellhead and the first casing pipe due to fixation of conductor and kelly sub in at least two points.

3 dwg