Patent ID: 7023213
Filing Date: 2006-04-04
Classification: G01V

Abstract:
1. A method for aquiring subsurface images, comprising: acquiring reference electric and magnetic measurements at a reference site using the natural electromagnetic field; acquiring a first set of electric and magnetic measurements in a survey area comprising a plurality of single-direction electric and magnetic measurements, each of the plurality of the single-direction electric and magnetic measurements comprises a same directional component; acquiring a second set of electric and magnetic measurements using controlled electric and magnetic sources; and determining in a single inversion a subsurface conductivity distribution from the first set of electric and magnetic measurements and the second set of electric and magnetic measurements by correlating the plurality of the single-direction electric and magnetic measurements with the reference electric and magnetic measurements according to the following equations: wherein E wherein the acquiring the first set of electric and magnetic measurements and the acquiring the second set of electric and magnetic measurements are performed with at least one subsurface imaging cable comprising a plurality of sensor modules spaced apart at a selected distance on the subsurface imaging cable, wherein the plurality of sensor modules are flexible such that the subsurface imaging cable is flexible and is adapted to be wound on a reel.