BOTTOM-HOLE ASSEMBLY FOR WELL DIRECTIONAL DRILLING Russian patent published in 1997 - IPC

FIELD: drilling equipment; applicable in drilling vertical wells in dipping gently anisotropic rocks. SUBSTANCE: stage bottom-hole assembly for well directional drilling has guide rod with drill bit and reamer. Supporting and centering member is installed so that ratio of distances from it to working end of drill bit and working end of reamer equals the ratio of supporting areas of the above-mentioned ends of reamer and drill bit. Cutting structured of reamer and drill bit are similar and diameters of reamer and drill bit are selected from relation , where Dp is diameter of reamer, m; Dd is diameter of drill bit, m. In course of drilling uniform contact of reamer cutting structure with circular bottom hole and constant ratio of contact areas of cutting structures of reamer and drill bit are preserved. As a result, mutual compensation of overturning moments acting on stage bottom-hole assembly is attained to provide for stabilization of direction of drilling of vertical well. EFFECT: higher efficiency. 1 dwg