MAGNETOSTATIC WELL-TRACKING TECHNIQUE FOR DRILLING HORIZONTAL PARALLEL WELLS

A directional surveying technique has been developed to monitor the di rectional drilling of two closely spaced, parallel horizontal wells. T he well-tracking technique, which is based on magnetostatic homing-in technology, uses the magnetic field of the casing in the first well as a reference for monitoring the drilling trajectory of the second well . For this purpose, the casing joints of the horizontal section of the first well are magnetized before running in the hole so that the uniq ue magnetic-field pattern can be detected in the second well with a me asurement-while-drilling (MWD) tool. Additional tools and access to th e first well are not required while drilling the second well. The well -tracking technique was applied successfully as part of Shell Canada's Horizontal Well Demonstration Project.