FIBER OPTIC CURRENT MONITORING FOR ELECTROMAGNETIC RANGING

摘要

A wellbore ranging system and method utilized between first and second wellbores includes an electromagnetic field sensing instrument disposed in the second wellbore, a conductive casing in the first wellbore, an electric current source exciting current flow in the conductive member, and a fiber optic sensor disposed adjacent the conductive member. The current flow along the conductive member results in a magnetic field which is measured by the sensing instrument. The fiber optic sensor includes a core that is responsive to the magnetic field in which it is disposed. The responsive core alters the optical property of an optical wave guide forming the sensor, which altered optical property can be utilized to measure the magnitude of the electrical current at the position of the sensor. The magnitude of the current and the measured magnetic field can be utilized to determine a range between the first and second wellbores.