METHOD FOR DOUBLE STRING RUNNING IN AND ADDING NEW JOINTS THERETO BY DRILLING FROM FLOATING VESSELS Russian patent published in 1994 - IPC

FIELD: drilling technique. SUBSTANCE: outer string 1 complete with shoe 2 and internal string 3 complete with hammer 4 are lowered to the basin bottom separately. The internal string is suspended on the outer string in such a way that the distance between hammer 4 and shoe 2 is equal the difference of the length of driving pipe 7 and height of circulating head 9. By adding a new joint, outer joint 5 and internal joint 6 are positioned vertical, circulating head 9 is fixed on core deflecting head 8, driving pipe 7 is connected to internal joint 6 being added, and circulating head 9 is connected to outer joint 5. Then the added joints - internal 6 and outer 5 are connected to their respective strings of the double column which is lowered from a floating vessel. Driving pipe 7 is lowered together with the internal string till hammer 4 rests on shoe 2. As this takes place, circulating head 9 is disconnected from core deflecting head 8. EFFECT: improved technique; reduced working time; simplified operations. 6 dwg