APPARATUS FOR COLMATAGE OF HOLE WALLS Russian patent published in 1995 - IPC

FIELD: drilling technique. SUBSTANCE: apparatus has the hollow housing 1, mounted between a pipe string and a drilling bit, the diffuser 2, secured to an inner wall of an inlet portion of the housing with possibility of adjustable axial motion. A smoothly narrowing cavity of the diffuser in its end portion transfers to a steep diffuser, providing sharp increase of an effective cross section area of the apparatus. The hollow trap 5 is mounted at some distance from a minimum flow through cross section of the diffuser with the aid of radially arranged blades 3,4, the trap being concentrically arranged relative to inner walls of the housing. The blades 3, being hollow ones, join a cavity of the trap 5 with colmatage nozzles 6 with the aid of flow through ducts. A drilling mud is being fed to the hollow housing, and after passing through the cavity of the diffuser it is being accelerated, and colmatant particles, containing in it, also are being accelerated. The colmatant, trapped by the trap 5, is being fed to the nozzles 6. EFFECT: enhanced serviceability. 3 cl, 2 dwg