CASING STRING TO FIX BRANCHED-OUT SHAFT OF BOREHOLE Russian patent published in 1996 - IPC

FIELD: borehole drilling. SUBSTANCE: casing string incorporates main string 1 and tail parts 2 and 3 integrated by setter 4 providing for simultaneous lowering of tail parts and for communication of ducts of string and tail parts after they are anchored in borehole shaft. Grouting of hole clearance in borehole shaft is conducted by pumping cement mortar through upper tail part 3. Fixing of branched-out borehole shafts by proposed casing string ensures grouting of the entire hole clearance of borehole shaft which leads to prolonged operational life of boreholes. EFFECT: prolonged operational life of boreholes. 2 cl, 9 dwg