Methods and systems to boost surface detected electromagnetic telemetry signal strength

A system for communication between a wellbore instrument and the Earth's surface, comprising:

• an electromagnetic field generator associated with the wellbore instrument, the electromagnetic field generator configured to encode measurements made by at least one sensor associated with the wellbore instrument;
• and
• an electromagnetic field detector in signal communication with the Earth's surface, the electromagnetic field detector comprising at least one of;
• a voltage measuring circuit connected between the drill string and an electrode disposed at a selected distance from the wellbore proximate the Earth's surface wherein the drill string and a wellbore casing are substantially electrically isolated from each other,
• a current measuring circuit for measuring current induced in the drill string wherein the drill string and the wellbore casing are substantially electrically isolated from each other, and
• a voltage measuring circuit connected between the well casing and the electrode wherein the casing and the drill string are electrically connected to each other.

A method for measurement in a wellbore, comprising:

• moving a wellbore instrument coupled to a drill string along an interior of a wellbore, the wellbore instrument including at least one sensor;
• generating an electromagnetic field in the wellbore instrument, the electromagnetic field comprising encoded measurements from the at least one sensor;
• measuring a signal corresponding to an amplitude and/or phase of the electromagnetic field;
• and
• decoding the encoded measurements from the measured signal, wherein the measured signal comprises at least one of;
• a voltage imparted across the drill string and an electrode disposed at a selected distance from the wellbore proximate the Earth's surface wherein the drill string and a wellbore casing are substantially electrically isolated from each other,
• a current induced in the drill string wherein the drill string and the wellbore casing are substantially electrically isolated from each other, and
• a voltage imparted across the well casing and the electrode wherein the casing and the drill string are electrically connected to each other.