Method and system for drilling underbalanced radial wells utilizing a dual string technique in a live well

摘要

A method and system (10) of drilling multiple radial wells (60) using underbalanced drilling, by first drilling a principal wellbore (16). There would then be provided a first carrier string (30) having a deflection member (50) on its lowermost end. There is then lowered a second drill string (12) that is deflected by the deflection member (50) from the principal wellbore (16). A second fluid is then pumped into an annular space between the second drill string (12) and the carrier string (30) to a position that it co-mingles with a first fluid. There is then provided a volume of fluid to establish an equilibrium within the carrier string (30). The direction of the deflection member (50) is reoriented to a second depth within the borehole. Finally, the drill string (12) and drill bit (46) is lowered to a second depth to drill a second radial well (60) while the well is alive and producing.