PIG FOR CLEANING OF INNER SURFACE OF TUBING STRING (VERSIONS) Russian patent published in 2014 - IPC E21B37/02 

FIELD: oil and gas industry.

SUBSTANCE: device contains three identical pigs fixed at the common bar, each having two identical radial knifes shaped as equilateral trapezium. All radial knives are fixed rigidly by larger bases of trapezium at lateral surface of the bar under angle of 90° to its surface parallel to its longitudinal axial line and are oriented towards each other per 180°. For the first radial knives working surfaces include lateral sides and the smaller base of trapezium. For the second radial knives working surfaces include only lateral sides of the trapezium. Leading edges of radial knives are sharpened at both sides. For the first version: the cutter in the form of an obtuse parallelogram is fixed at the smaller base of the trapezium for the second radial knives with inside sharpening of the leading edge. The cutter is fixed diagonally connecting obtuse angles and curved towards the wall of the cleaned tubing and equi-spaced from it. For the second version: radial knives of the outermost scrapers lie in the same plane and opposite in space in regard to the longitudinal axis of the bar. Radial knives of the medium scraper are unfolded in regard to the outermost ones per 90°. The cutter of two identical plates shaped as bands with grinding of both edges curved inside is fixed rigidly in the scrapers.

EFFECT: decrease in resistance to cutting, increase in cutting force, improved quantity of cleaning.

2 cl, 11 dwg