1965 Paper I-G

FACTORS AFFECTING ACOUSTIC AMPLITUDE LOGS - AND THEIR EVALUATION

L. G. Huntley Humble Oil & Refining Company - Central Region

ABSTRACT

Many acoustic amplitude hogs are being run under the impression that the compressional amplitude reductions observed reflect only reservoir characteristics, such as fracturing, fluid content and so forth. The centering of the sonde in the borehole is shown to have an equally strong influence on compressional amplitude, however. Unless a single received monitoring curve is run, there is no way of determining whether the tool is properly centered in the hole. The example shown illustrates the use of such a curve in interpreting compressional amplitude logs. An outgrowth of the study indicates that tool decentralization occurs where drilling methods were changed from coring to conventional drilling.