Patent ID: 8704523

Claim:
A method for making an electromagnetic survey of a formation surrounding a borehole having a casing comprising: deploying an electromagnetic transducer into a section of the borehole that is cased with a conductive casing; deploying a casing property analysis tool into the section of the borehole, the casing property analysis tool comprising at least one other transducer; making electromagnetic survey measurements of the formation with the electromagnetic transducer; making a plurality of measurements of casing property data with the casing property analysis tool at a plurality of depths in the borehole, the casing property data representing one or more properties relating to the casing for the section of the borehole; correlating each measurement of casing property data according to a depth at which that measurement was taken; directly calculating a casing factor based on the depth correlated casing property data; compensating for attenuation in the electromagnetic survey measurements with the directly calculated casing factor; and deriving, based on the depth correlated casing property data, one or more casing parameters selected from the group consisting of casing thickness, casing conductivity, and relative magnetic permeability, wherein the deriving is performed independent of reference to the electromagnetic survey measurements; wherein at least one of the other transducers using to measure the depth correlated casing property data is deployed at a different time than said electromagnetic transducer into the section of the borehole.