Patent ID: 7822562
Filing Date: 2010-10-26
Classification: G01V,Y02A

Abstract:
1. A method for correcting electromagnetic field data from a controlled source electromagnetic survey of a subterranean underwater region to reduce air wave noise in signals measured at survey receivers located in the water layer at or near the water bottom, said method comprising: (a) obtaining at least one conductivity or resistivity value for the water; (b) using a computer to simulate synthetic electromagnetic field data for at least one selected survey receiver location assuming an all-water earth model based on the survey region except with air and below-water layers replaced by more water, using survey source locations associated with the selected receiver locations and source signal generating parameters and the at least one water conductivity or resistivity value; (c) using a computer to simulate synthetic electromagnetic field data for the selected survey receiver locations assuming an air-water earth model based on the survey region except with more water replacing below-water-bottom sediment, using survey source locations associated with the selected receiver locations and source signal generating parameters and the at least one water conductivity or resistivity value; and (d) calculating electromagnetic field values corresponding to a hypothetical water-sediment earth model based on the survey region except with more water replacing an air half space, said calculation using measured survey electromagnetic data and synthetic data from the all-water model and the air-water model, wherein said calculated electromagnetic field values represent measured data adjusted to remove air wave noise.