Study on a Modified Fixed Central-loop TEM System for Deep Sounding

Abstract

The central-loop TEM technology has been widely used in geological exploration. For efficient working, a square (or rectangular) loop is generally used instead of the circular one. One may define a range of one ninth of central part (can be approximately regarded as uniform) as the central survey location, which can be referred as a modified central-loop configuration. However, the obtained field parameters at such non central positions usually calculated by the central-loop formula result in decreased accuracy in the explanation. The large-fixed loop has advantage to calculate the induction potential at any point inside or outside the loop. We in this study introduced the formula for the larger fixed loop into the above modified central-loop system and solve the problem, in which electromagnetic response of any field point has been obtained by using an electric dipole integration method. Both theoretical modeling and real application indicate that such combination not only improves the accuracy for the TEM survey, but also enlarges the exploration depth due to a large loop is used in the deployment.