LOWER SEPARATING CEMENTING PLUG Russian patent published in 2013 - IPC E21B33/16 

FIELD: oil and gas industry.

SUBSTANCE: plug includes drilled metal core with a through central hole with a pressed support annular disc. Three integral elastic cuffs covering the hole of the core with a rubber membrane from below are coated with rubber on the core. Upper cuff is self-sealing, and two lower cuffs are of split type and made in radial direction in the form of several blades. At that, upper blade covers lower cross section, and in circumferential direction, the cuffs are made in the form of arc-shaped triangular projections in the cross section, the sharp edge of which is directed to wall of casing string. Besides, lower surface of the above edges is made at an angle of 85°-95° relative to the core axis.

EFFECT: increasing cleaning efficiency of internal surface of casing string and inter-end cavities of pipes at the interval of sleeve joints from adhesive film and residues of clay mud.

1 dwg