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Optically Imaging a Wellbore Through Drilling Mud

IP.com Disclosure Number: IPCOM000246471D
Publication Date: 2016-Jun-09
Document File: 1 page(s) / 14K

Publishing Venue

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Abstract

Currently, the only optical images of wellbores are obtained in air-filled or clear-liquid-filled wellbores because of the high optical attenuation of drilling muds, primarily from scattering. What is proposed here is to apply techniques for imaging through scattering media to optical borehole imaging. One method for optically imaging through scattering media is to time-gate the reflections of a pulse of light and only record the earliest reflected light arrivals, which represent the ballistic photons that were not scattered and therefore took the shortest path in the least amount of time. Alternatively, one could use optical coherence tomography or holography. However, all of these techniques would add considerably to the cost and complexity of a downhole implementation. What is proposed is to take an ordinary high resolution monochrome image and then process this image using autocorrelation to extract a reconstructed image of what lies below the scattering media.

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Title:  Optically Imaging a Wellbore Through Drilling Mud

Abstract:  Currently, the only optical images of wellbores are obtained in air-filled or clear-liquid-filled wellbores because of the high optical attenuation of drilling muds, primarily from scattering.   What is proposed here is to apply techniques for imaging through scattering media to optical borehole imaging.  One method for optically imaging through scattering media is to time-gate the reflections of a pulse of light and only record the earliest reflected light arrivals, which represent the ballistic photons that were not scattered and therefore took the shortest path in the least amount of time.  Alternatively, one could use optical coherence tomography or holography.  However, all of these techniques would add considerably to the cost and complexity of a downhole implementation.  What is proposed is to take an ordinary high resolution monochrome image and then process this image using autocorrelation to extract a reconstructed image of what lies below the scattering media.

Description:  Drilling muds are highly attenuating of both visible and near-infrared light mainly because of scattering by particulates, which can attenuate light transmission by 4 or more orders of magnitude over a 2 mm path length.  While other approaches would likely work downhole, this approach appears to be the easiest to implement.  It may be necessary to design the tool as a pad tool or a tool a significant wellbore fluid...