Method and system for removing effects of conductive casings and wellbore and surface heterogeneity in electromagnetic imaging surveys

A system for characterizing a reservoir, comprising:

• a plurality of electromagnetic transmitters and receivers, one or more of which are disposed within a wellbore positioned relative to the reservoir to be characterized;
• means for normalizing measured voltage data by transmitter moment;
• means for sorting the normalized voltage data into common receiver profiles;
• means for densely resampling transmitter locations using common positions for the receiver profiles;
• means for coarsely resampling the data at discreet transmitter locations;
• means for defining a starting model for inversion;
• means for weighting the data by a factor;
• means for converting the normalized voltage data to ratios;
• and
• means for calculating a conductivity image using a ratio inversion method;
• wherein a common receiver profile comprises measurements made during a one of a crosswell, surface-to-borehole, borehole-to-surface, or single-well electromagnetic survey with a receiver fixed at a given depth.

A computer program product embodied in a computer storage medium, the computer program product operable for characterizing a reservoir, comprising the program steps of:

• normalizing measured voltage data by transmitter moment;
• sorting the normalized voltage data into common receiver profiles;
• densely resampling transmitter locations using common positions for the receiver profiles;
• coarsely resampling the data at discreet transmitter locations;
• defining a starting model for inversion;
• weighting the data by a factor;
• converting the normalized voltage data to ratios;
• calculating a conductivity image using a ratio inversion method;
• and
• verifying that an inversion has converged and the image is geologically reasonable;
• wherein a common receiver profile comprises measurements made during a one of a crosswell, surface-to-borehole, borehole-to-surface, or single-well electromagnetic survey with a receiver fixed at a given depth.