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.2 •. .. ., <br />Variable density (VDL) - Pipe signals, formation signals, <br />and fluid signals are usually easy to recognize on the VDL. <br />If these signals can be identified, a practical <br />determination for the presence or absence of cement. can be <br />made. VDL is logged on the 5 foot spaced receiver.. <br />Casing collar locator (CCL) - Used to correlate the bond log <br />with cased hole logs and to match casing collars with the <br />collars that show up on the VDL portion of the display. <br />Gamma ray - Used to correlate the bond log with other logs. <br />PART III - LOGGING TECHNIQUE <br />Calibrate the tool in free pipe at the shop, prior to, and <br />following the log run. Include calibration data with log. <br />Run receivers spaced 3 feet and 5 feet from transmitter. <br />Run at least 3 bow-type or rigid aluminum centralizers in <br />vertical holes, 6 centralizers in directional holes. A CCL <br />is not an adequate centralizer. <br />Complete log header with casing/cement data, tool/panel <br />data, gate settings and tool sketch showing centralizers. <br />Set the amplitude gate so that skipping does not occur at <br />amplitudes greater than 5 mV. <br />Record amplitude with fixed gate and note position on log. <br />Record amplified amplitude on a 5X scale for low amplitudes. <br />Record amplitude and travel time on the 3 foot receiver. <br />Record travel time on a 100 µs scale (150 - 250, 200 - 300). <br />Logging speed should be approximately 30 ft/min. <br />Log repeat sections. <br />PART IV - QUALITY CONTROL <br />Compare the tool calibration data to see if the tool <br />"drifts" during logging. Differences in the calibration <br />data may require you to re-log trie well to obtain reliable <br />data. <br />Compare repeat sections to see if logging results are <br />repeatable. <br />Check the logged free pipe travel times with the service <br />company charts for the specific tool and casing size used. <br />Since the travel times depend on such factors as casing <br />weight, type of fluid in the hole, etc., these charts should <br />be used only as guidelines. When you are confident of the <br />