FIELD: oil industry.
SUBSTANCE: invention relates to the oil industry, in particular to devices for shutting off the wellhead during lowering and retrieval of a pipe string in order to prevent foreign objects from falling into the well, as well as to clean the pipes from the well fluid lifted from the well. The wellhead self-centering wiper contains a body with a central hole and a slot that mates with the central hole. The body is equipped with holes for attaching the wiper to the wellhead. A wiping element is installed inside the case, made in the form of an elastic cuff, fixed between the upper and lower metal rings with the help of pins. The elastic cuff is equipped with a central hole and radial cuts. The housing is equipped with an internal cylindrical recess from below, in which a wiping element is installed with the possibility of rotation relative to the housing, as well as with the possibility of limited axial and radial movement relative to the housing. The elastic cuff of the wiping element, equipped with a central hole, is made of two stages: on top with a smaller diameter - d1 under the body of the pipe string, and on the bottom with a larger diameter - d2 under the pipe coupling. The upper step of the two-stage elastic cuff with a diameter of – d1 is equipped with radial cuts. The upper step with a diameter - d1 of a two-stage elastic cuff has a greater thickness - h1than the thickness h2 of the lower step with a diameter - d2. Two rows of threaded holes for studs are made in the body from above and below at an angle of 180° with respect to each other and with an offset of 45° for fastening the wiper from above to the spider, and from below to the wellhead flange. The inner diameters - Dr of the upper and lower metal rings are greater than or equal to the inner bore diameter - Dw of the production string of the well.
EFFECT: simplifying the design, improving the reliability of the device and the quality of cleaning the surface of pipes and couplings of tubing joints (TJ) or BT pipes pulled from the well, as well as eliminating time losses when passing pipe couplings through the device.
1 cl, 2 dwg
