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<br />Circumjerenrial Acoustic Scanning Too( (CAST) impedance values for fluids are very consistent and manifests itself as a fairly straight line on the log. Cement slurties, <br />are more variable and show up as curves with much more activity or variability. By analyzing the value and the character of the impedance curves, it is possible to <br />successfully evaluate the cement quality of conventional and lightweight cements. Typical impedance values for common materials or fluids are; <br />Gas or air < .5 high activity curve response <br />Water LS flat consistent curve response <br />Drilling Mud 1.5 - 2.5 IIat consistent curve response <br />Lightweight Cements <I - 4 high activity curve response <br />Conventional Cements 2 - 6 medium to high activity curve response depending consistency of slurry <br />Cement Bond Log (CBL) tools evaluate cement bonding to pipe and formation by measuring the changes in sound waves traveling through casing, cement, <br />and formation. Log presentations include a pipe amplitude curve and aMicro-Seismogram ®display in the form of light to dark shades. The amplitude <br />curve in lightweight cements will not read as low as published values for conventional cements. Comparisons to lowest value and to free pipe value are <br />necessary to fully evaluate. Pipe signal will not completely disappear in lightweight cement as in conventional cements. <br />Respectfully, <br />Tom Riebel <br />Halliburton Energy Services <br />Halliburton does not guarantee the accuracy of any interpretation of the log data, conversion of log data to physical rock parameters or recommendations which may be <br />given by Halliburion personnel or which appear on [he log or in any other form Any user of such data, interpretations, conversions, or recommendations agrees that <br />Halliburton is not responsible except where due to gross negligence or willful misconduct, for any loss, damages, or expenses resulting from the use thereof. <br />