BOTTOMHOLE FEED MECHANISM Russian patent published in 2007 - IPC E21B19/86 

FIELD: oil and gas industry, particularly used for horizontal and nearly horizontal well bore sections, namely apparatus for feeding the rods or cables.

SUBSTANCE: feed mechanism comprises hydraulic cylinder having connection member to connect thereof to rotary unit so that twisting moment, axial load and drilling fluid flow may be transmitted therefrom. Feed mechanism also has piston passing in hydraulic cylinder and provided with connection member arranged from side facing drilling bit. The connection member may transmit twisting moment, axial load and drilling mud flow to drilling bit. Piston also has inner channel to permit drilling mud flow passage from hydraulic cylinder interior. Hydraulic cylinder and piston are connected with each other so that hydraulic cylinder and piston may perform relative axial reciprocation limited in each direction to transmit twisting moment, axial load and drilling mud flow from hydraulic cylinder to piston so that drilling mud flow passes in inner piston channel. Arranged between drilling mud flow inlet of inner piston channel and outlet thereof facing drilling bit and mining annuity is flow resistance member. Inner piston channel has restricted section with decreased throat formed from end thereof facing rotary unit. Rod passes in said restricted section so that a gap is formed in-between. The rod is fixedly secured with respect to hydraulic cylinder and has length corresponding to piston travel. Rod has diameter varying at rod ends. Gap between opposite rod and restricted inner channel section surfaces provides hydraulic drilling mud flow resistance having value varying in dependence of rod diameter as piston moves in extreme positions relatively hydraulic cylinders.

EFFECT: possibility to obtain information concerning piston position in hydraulic cylinder from drilling mud supply line pressure change.

6 cl, 2 dwg