| US 7,333,893 B2 | ||
| Method for spatially interpreting electromagnetic data using multiple frequencies | ||
| Olivier M. Burtz, Houston, Tex. (US); James J. Carazzone, Houston, Tex. (US); and Dmitriy A. Pavlov, The Woodlands, Tex. (US) | ||
| Assigned to ExxonMobil Upstream Research Company, Houston, Tex. (US) | ||
| Filed on Feb. 23, 2006, as Appl. No. 11/360,303. | ||
| Claims priority of provisional application 60/659251, filed on Mar. 07, 2005. | ||
| Prior Publication US 2006/0217889 A1, Sep. 28, 2006 | ||
| Int. Cl. G01V 9/00 (2006.01); G01V 11/00 (2006.01) | ||
| U.S. Cl. 702—14 [702/7; 702/16] | 13 Claims |
| 1. A data-processing method for reducing masking effects of shallow resistivity structures on an electromagnetic survey of
a subsurface region, comprising:
(a) selecting a first survey data set generated at a first source frequency, said first source frequency having been selected
to penetrate only said shallow resistivity structures;
(b) selecting a second survey data set corresponding to a second source frequency lower than said first source frequency,
thereby revealing deeper lying resistivity structures of the subsurface region as well as said shallow resistivity structures;
(c) calculating the shallow resistivity structure by solving electromagnetic field equations using the survey data set generated
at the first source frequency; and
(d) using the calculated shallow resistivity structure and the electromagnetic data from the second survey to distinguish
shallow response from deeper response.
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