Determining Correction Factors Representing Effects of Different Portions of a Lining Structure

Abstract

To determine effect on a magnetic field caused by a lining structure in a wellbore, an array may be deployed into the wellbore lined with the lining structure. The array comprises a plurality of sensors including sensor A configured to operate as a transmitter, sensor B configured to operate as either a transmitter or a receiver, and sensor C configured to operate as a receiver. The array measures magnetic fields using sensor B as a receiver and sensor C in response to activation of sensor B as a transmitter and sensor A. A plurality of lining structure correction factors can be calculated based on the measured magnetic fields, based on the reciprocity of the sensors.

1 .- 22 . (canceled) 
     
     
         23 . A method, comprising:
 deploying an array comprising a plurality of sensors, at least one of which is configured to operate as either a transmitter or a receiver into a wellbore comprising an electrically conductive tubular structure;   activating a plurality of the sensors as transmitters;   operating a plurality of the sensors as receivers to measure magnetic fields between couplings of the plurality of sensors; and   calculating a plurality of correction factors for the electrically conductive tubular structure based on the measurements.   
     
     
         24 . The method of  claim 23 , further comprising applying the plurality of correction factors to eliminate the effect of one or more tubular structures for at least one of: 1) improved crosswell evaluation of a reservoir, 2) improved surface-to-borehole evaluation of a reservoir, 3) improved single well evaluation of a reservoir, 4) improved steam assisted gravity drainage drilling, 5) improved casing evaluation applications, 6) improved well avoidance for plural wells in close proximities, 7) improved well intersection techniques, and 8) improved reservoir monitoring through casing. 
     
     
         25 . The method of  claim 23 , wherein the sensors are physically separated in the array by a minimum separation defined by at least one of 1) frequency and 2) one or more casing characteristics, and 3) sensor characteristics (core size and core properties, or sensor type); said minimum separation being sufficiently far enough that the correction factor for each sensor is separable from the correction factor for each adjacent sensor.