System for Drilling Parallel Wells for SAGD Applications

摘要

A system for ranging between two wellbores. The target wellbore includes a conductive body (e.g., casing) disposed within a portion of the target wellbore. A second wellbore includes an electromagnetic field sensing instrument positioned within the wellbore. A current delivered to the conductive body in the target wellbore results in a magnetic field emanating from the target wellbore. The electromagnetic field sensing instrument is utilized to measure an electromagnetic gradient based on the magnetic field, which electromagnetic gradient can be utilized to determine the range between the wellbores.

主权项

1. A system for determining distance and direction to a target wellbore from a second wellbore being drilled, the system comprising:
a conductive body disposed in at least a portion of the target wellbore; a drill string in the wellbore being drilled, the drill string carrying a measurement while drilling system; an electric current supply disposed to excite a current flow on the target wellbore by a direct electrical connection to the target wellbore; and an electromagnetic field sensing instrument in the second wellbore being drilled, the electromagnetic field sensing instrument being responsive to the electromagnetic field and to radial gradients of the electromagnetic field generated by the electrical current in the target wellbore.