Intersecting a wellbore using the Rotating Magnet Ranging System: RMRS
The Vector Magnetics Rotating Magnet Ranging Service uses the rotation of a magnetized bit sub in a first well to create a time-varying magnetics field that can be detected more than 60 meters away. A wireline tool with tri-axial accelerometers and multi-frequency magnetometers in a second well measures the magnetic field magnitude and orientation. The measurements correlate to the depth in the drilling well. Typical applications are measuring and controlling wellbore separation or for homing-in to intersect and join wellbores in various geometries.
The RMRS system has been used for over 200 Coal Bed Methane (CBM) horizontal to vertical intersections, and over 400 Steam Assisted Gravity Drainage (SAGD) heavy oil producing wellpairs.
In the frequent CBM wellbore intersection application of the Rotating Magnet Ranging System the magnetic bit sub is located directly behind the drill bit and the receiver on wireline in the target well. Accurate position information can be acquired at more than 150 feet of lateral separation, allowing for significant trajectory correction prior to intersection. Intersecting targets ranging from 7 inch casing to 6 foot diameter cavities is routine.
When drilling Parallel SAGD wellbores the magnetic bit sub is located in the second well of a pair and the receiving tool in the first or "reference" wellbore to be paralleled. The tool is either pumped down tubing or tractored in the reference well to stay opposite the bit sub and continuously monitor separation.
