Patent ID: 8011451
Filing Date: 2011-09-06
Classification: E21B,H01F,H01J,Y10T

Abstract:
1. A method for forming two or more wellbores in a subsurface formation, comprising: forming a first wellbore in the formation; directionally drilling a second wellbore in a selected relationship relative to the first wellbore; transmitting a first electromagnetic wave from a first transceiver in the first wellbore and sensing the first electromagnetic wave using a second transceiver in the second wellbore; transmitting a second electromagnetic wave from the second transceiver in the second wellbore and sensing the second electromagnetic wave using the first transceiver in the first wellbore; continuously assessing a position of the second wellbore relative to the first wellbore using the sensed first electromagnetic wave and the sensed second electromagnetic wave; and adjusting the direction of drilling of the second wellbore so that the second wellbore remains in the selected relationship relative to the first wellbore.