Characterizing an earth subterranean structure by iteratively performing inversion based on a function

An article comprising at least one computer-readable storage medium containing instructions that when executed cause a computer to:

• receive measured voltage data collected by the EM receivers in response to transmission by the one or more EM sources;
• compute, based on a model, predicted EM data;
• and
• iteratively perform inversion according to a function that computes a difference between the measured voltage data and a product of a term containing the predicted EM data and a term containing distortion data that accounts at least for distortion effect by an environment of the measurement assembly,
• wherein iteratively performing the inversion solves for parameters of the model and the distortion data;
• wherein the measured voltage data is collected from one of a cross-borehole survey, a surface-to-borehole survey, a borehole-to-surface survey, a single-well borehole-to-borehole survey, and a surface controlled source electromagnetic survey.

A system comprising:

• a measurement assembly including one or more electromagnetic (EM) sources and EM receivers;
• and
• a data processing computer to:
• receive measured voltage data collected by the EM receivers in response to transmission by the one or more EM sources;
• compute, based on a model, predicted EM data;
• and
• iteratively perform inversion according to a function that computes a difference between the measured voltage data and a product of a term containing the predicted EM data and a term containing distortion parameters that account at least for distortion effect by an environment of the measurement assembly,
• wherein iteratively performing the inversion solves for parameters of the model and the distortion parameters;
• wherein the measured voltage data is collected by the EM receivers in one of a cross-borehole survey, a surface-to-borehole survey, a borehole-to-surface survey, a single-well borehole-to-borehole survey, and a surface controlled source electromagnetic survey.