--> Abstract: LOGCAL: A New Tool to Analyze the Geophysical Logs, by S. Peng and A. H. Coogan; #90954 (1995).

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Abstract: LOGCAL: A New Tool to Analyze the Geophysical Logs

Peng Shengfeng, Alan H. Coogan

LOGCAL is an interactive and user-friendly program written in Microsoft Quick Basic for use on IBM PC and its compatible desktop computers. The program is designed to handle the various time-consuming geophysical log readings and calculation problems.

The system provides subroutines and functions for digitizing, converting and log calculations. The digitizer used in this example is G-7, however, it is easy to switch to other kinds of digitizers which convert graphic information into digital form suitable for further analysis. Digitizing oil and gas well paper logs is undertaken using a point or line mode. The line mode (stream digitizing) is more accurate than point mode (peak to peak digitizing), but substantially more memory is required than for point mode. Fortunately, LOGCAL's data conversion function makes it easy to convert the digitized data into one point per foot (or other user's choice of interval) The generated, formatted ASCII file is then ready for editing or calculation. The digitized log can be adjusted for different scales. Correction for skewness can be made and the data set sorted according to depth or other geophysical log value. LOGCAL's calculation function allows the user to acquire various parameters such as sand qualities, slice map data, neutron porosity, density and density porosity, total thickness of a given lithology and so on. The LOGCAL data can be plotted on the screen as a graphic log or calculated log for different parameters. User can highlight (shadow) certain potion of the display (e.g., >75% sand on the gamma-ray log). Finally, the program has a function to automatically convert the digitized log into the format recognizable by commercial software package SURERTM. The data imported into SURFERTM can be contoured or used as a part of log cross section. L GCAL avoids the annoying process of photocopying paper logs, changing scales, tracing by hand and greatly increases the accuracy of cross sections.

AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York