Coincident loop transient electromagnetic master curves for interpretation of two-layer earths

A set of apparent conductivity master curves has been calculated for the coincident loop transient electromagnetic (TEM) method used over a two-layer earth. Conductivity contrasts range from 0.001 to 1000. Loop radius/layer depth ratios range from 0.01 to 100. The time range is sufficient to see the entire shape of the curves from the early to the late time asymptotes. These curves allow the determination of the parameters of a two-layer earth for accurate data over a sufficient time range. Examples using the curves to interpret multilayered earths are given. The curves are also used to show the limitations placed on interpretation by existing TEM equipment.