SCREW MOTOR FOR CLEANING OF CASING PIPE INTERNAL SURFACE Russian patent published in 2002 - IPC

FIELD: equipment of major repair of oil and gas wells, particularly, devices for cleaning of casing pipe internal surface from cement crust, deposits of gypsum and paraffin formed in the course of well operation, and for drilling out of cement plugs in casing string. SUBSTANCE: screw motor has screw with external spiral teeth, body with internal spiral teeth whose number Zb is greater than Zs of external spiral teeth of screw one. Body axis O₁O₁ is displaced relative to axis O₂O₂ by eccentricity value E equaling one half of tooth radial height h. Screw has central channel and outlet holes for communication of central channel with cavity between screw teeth and body teeth. Located in screw upper part is upper bearing unit made in the form of disc with circular face bearing surface for engagement with body upper face bearing surface. Located in screw lower part is lower bearing unit in the form of disc with circular face bearing surface for engagement with body lower face bearing surface. Connected to body is destructing member which external surface of Dp diameter has longitudinal blades. Centralizer is made on screw upper end for base of screw motor inside casing pipes. Body executes planetary motion relative to screw under action of unbalanced hydraulic forces. Destructing member executes by its blades, apart cutting action, also crushing and shearing action on cement crust, deposits of gypsum paraffin, etc. to clean internal surface of casing pipes over entire perimeter of its internal cross section. EFFECT: improved cleaning. 6 cl, 9 dwg