Methods are disclosed for drilling a first well and a second well. The method includes measuring direction and inclination for at least one of the bottom hole assemblies (BHAs) in the wells, generating a magnetic field in at least one of the BHAs and measuring the magnetic field at the other BHA. The...http://www.google.ca/patents/US7703548?utm_source=gb-gplus-sharePatent US7703548 - Magnetic ranging while drilling parallel wells
