GEAR FOR MUD INJECTION INTO HIGH-PERMEABLE SEAMS Russian patent published in 1996 - IPC

FIELD: oil and gas production. SUBSTANCE: gear is composed of hollow housing 1 with threaded connections to couple it to drill pipe string. Blade in the form of truncated cone is made fast to housing. Blades are set with hard material to improve their wear resistance. Triangular straps are continuations of side lines of blades and are attached above them. Plane of cross-section of truncated cone of blades forms together with rotational axis of gear angle Ψ₁, determined by formula Ψ₁=90^°-Ψ-ΔΦ, where Φ is angle formed by vector of relative velocity of particle movement and rotational axis of gear found from relation specified in text of description; angle Dv - is formed by vector of relative velocity of particle movement and plane of axial section of blade determined from relation ΔΦ=arctg(sinβ/sinα),deg., where β - is inclination angle of conical surface to well wall in plane of angle Ψ₁, amounting to ±5 deg; α - is angle formed by surfaces of segments of truncated cone with wall of well in cross-section of gear found by formula α=arcsin[(D_к/2ρ)-1], deg., , where ρ - is curvature radius of blades, m; α is wedge-shaped clearance with well wall in plane of axial section of blade within range 0 ≅ tgα < f,, where is friction coefficient of hard particles against rock found from relation α = arcsin(sinα_n/ cos ΔΦ), deg,. Average angle of inclination of triangular straps to rotational axis is determined by following inequality Ψ₂<arctgf_м, where f_m is friction coefficient of pressed sludge against metal. Gear is placed above drill bit and is lowered on drill pipe string into interval where intensive absorption is possible. Then well is washed with drilling mud with simultaneous rotation of drill bit, after this drilling of well is started. EFFECT: treatment of cavernous and jointing formations. 3 dwg