Patent ID: 7840356

Claim:
A computer-implemented method for determining three independent angles specifying orientation of electromagnetic receivers in a marine electromagnetic survey, comprising: (a) selecting survey data according to criteria including signal-to-noise ratio and degree of distortion, wherein the survey data was recorded by the electromagnetic receivers after they were dropped from above to fall freely to the seafloor; (b) creating a model representing the survey's source-receiver geometry and media for transmission of electric signal, said model comprising three receiver orientation angles, a resistivity model, and electromagnetic source and receiver parameters; and (c) solving Maxwell's electromagnetic field equations with the model and selected survey data as input information and said three receiver orientation angles as unknowns, said solution being performed by iterative numerical inversion in which a difference between electromagnetic survey data computed from the model and the selected recorded electromagnetic survey data is minimized by varying the model, resulting in trial and error solutions for the three receiver orientation angles.