Magnetic ranging while drilling using an electric dipole source and a magnetic field sensor

A method of drilling a well comprising:

• drilling a horizontal well in a field having a vertical well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap;
• generating a current on the drill collar of the BHA while drilling the horizontal well;
• and
• measuring from the vertical well a magnetic field caused by the current on the BHA.

A method of drilling a well comprising:

• drilling a second horizontal well above a first horizontal well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap;
• generating a current on the drill collar of the BHA while drilling the second horizontal well;
• and
• measuring from the first horizontal well a magnetic field caused by the current on the BHA.

A method of drilling a well comprising:

• drilling a new well in a field having an existing well;
• generating a magnetic field from an electric dipole in the new well;
• and
• measuring the magnetic field using a magnetometer disposed in the existing well.