New Developments in Real Time Processing of Full Waveform Acoustic Televiewer Data

摘要

As compared to the existing Televiewer tools, which measure one echo (amplitude andrntraveltime), the new full waveform Acoustic Borehole Imager tool (ABI) is a multi-echornsystem. This is achieved by digital recording of each reflected acoustic wave train.rnThen, on- line processing of the acoustic data is made by an attached DSP to extract allrnvaluable information, which is further compressed before sending to the surface such thatrnno special requirements are imposed on logging cable, data transmission rates or loggingrnspeed.rnRecording of full acoustic signals enables major improvements of the dynamic range ofrnthe system. Indeed, knowledge about the echo from the acoustic window gives thernpossibility to predict tool generated coherent noise and allows to detect an echo from thernborehole wall which is much smaller than coherent noise signals.rnIn a Cased Hole context the system can automatically adapt to situations where the tool isrnrun inside plastic casing to record both reflections at the casing and at the borehole wall.rnEffective imaging of formations through PVC-casing requires the casing to be centralizedrnin the borehole.rnIn a Casing Thickness context the tool can detect the reflections from the inner wall andrnthe outer wall of any casing to calculate inner corrosion, outer corrosion, and remainingrncasing thickness. If cementation was made information can be gathered about thernabsence of cement and the quality of cement bonding.rnUnder the new concept future challenges and costumer requirements can be solved withrnthe same tool hardware just by upgrading the DSP software. Upgrades can be made byrnsoftware from the surface unit.rnThe text of full paper is undergoing critical review for, the 'soon-to-be-published' specialrnKEGS/MGLS Symposium issue of the Journal of Applied Geophysics (JAG). Under JAGrnpublication guidelines, this manuscript is not available for the CD.