Patent ID: 9069097
Filing Date: 2015-06-30
Classification: E21B,G01V

Abstract:
1. A downhole tool system for making electromagnetic measurements of a subterranean formation comprising: a first downhole tool deployable in a metallic cased wellbore and adapted to make electrical contact with a wall of the metallic casing so as to establish a current loop that partially includes the metallic casing wall; and one or more receivers deployable and adapted so as to inductively detect a field in the formation that has been produced by the established current loop; wherein the first downhole tool comprises a first unit deployable and adapted to make electrical contact with the metallic casing wall at a first location and a second unit deployable and adapted to make electrical contact with the metallic casing wall at a second location, wherein the established current loop includes at least a portion of the casing wall between the first and second location; and wherein the first and second units are configured to be repositionable in relation to one another while the tool is deployed downhole to alter the distance between the first and second locations while the tool is deployed downhole.