Method for determining orientation of electromagnetic receivers

Method for determining receiver orientation angles in a controlled source electromagnetic survey, by analyzing the survey data. For a given survey receiver, two data subsets are selected. (43, 44). The two subsets may be from two offset ranges that are geometrically symmetrical relative to the receiver location. Alternatively, the second subset may be a computer simulation of actual survey data. In either instance, an orientation is assumed for the receiver (45), and that orientation is used to compare component data from the two subsets that can be expected to match if the assumed orientation angle(s) is (are) correct (46). The mismatch is ascertained, and the assumed orientation is adjusted (45) and the process is repeated.