METHOD OF DRILLING OF ADDITIONAL WELLBORE FROM PRODUCTION STRING Russian patent published in 1997 - IPC

FIELD: well drilling, particular, technology for drilling of additional wellbores from production string. SUBSTANCE: method of drilling of additional wellbore of smaller diameter by means of deflecting tool. After sidetracking of additional wellbore, the part of production string in zone of sidetracking and adjacent to the main wellbore of additional wellbore are rammed and cased with expandable profiled pipes, and then, drilling is continued with the diameter corresponding to the diameter of side tracking of additional wellbore and upon its completion, the uncased part is expanded to the diameter of expanded parts and cased with expanded pipes whose diameter corresponds to the diameter of the expanded pipes installed beforehand. EFFECT: higher efficiency. 2 dwg