Schlumberger Technology Corporation

John Corben

Ashley Bernard Johnson

Gary L Rytlewski

Michael Paul Barrett

Harry G Barrow

Charles Jenkins

This invention relates in general to measuring depth of well-tools, such as logging tools or the like, in a borehole. Embodiments of the present invention may provide for disposing transponders along a wireline that may be used to suspend and move the well-tool in the borehole, where the transponders may be disposed along the wireline at predetermined locations. A reader may be located at a reference location and may read when a transponder passes through the reference location and this information may be used to determine the depth of the well-tool in the borehole. Additionally, this invention provides for combining depth measurements from the transponders with measurements from odometer wheels in frictional contact with the wireline and/or time of flight measurements of optical pulses passed along a fiber optic cable coupled with the wireline to accurately and robustly measure the depth of the wireline in the borehole.

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Colonia Granada, Mexico

John Corben