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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 441

Last Page: 441

Title: KOALA--Minicomputer Log Analysis System for Geologists: ABSTRACT

Author(s): John H. Doveton, Harold W. Cable

Article Type: Meeting abstract


An interactive computer medium for log analysis is generally preferable to batch processing in view of the almost inevitable uncertainties regarding key petrophysical parameters and even the compositional nature of subsurface units. KOALA is an interactive package of log analysis routines developed by the Kansas Geological Survey and run on its minicomputer system. Resolution of mineralogic and porosity proportions is made by either maximum variance, unique solution, or least-squares matrix algorithms, depending on the degree of determinancy prescribed by the number of components as related to number of logs. An alternative linear programming method is also available for the incorporation of local geologic information to aid in solutions with restricted log data. Reservoi analyses of fluid saturations, permeability indices, and invasion characteristics are programmed following standard solution procedures. Wherever possible, error diagnostics are generated to alert the user to inconsistencies which are implied between the solutions, input parameters, and log values. Intelligent response to these diagnostics allows the user to initiate revisions in a learning sequence of modifications that converge on a satisfactory solution.

Dipmeter data are processed via a variety of graphic options such as flat and perspective cylindrical projections, Wulff and Schmidt polar plots, together with eigenvector analyses of vector fabrics. A simple synthetic seismic modeling procedure is also included and multi-variate statistical procedures, such as discriminant functions and factor analysis, will be incorporated to serve as aids in pattern recognition studies.

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Copyright 1997 American Association of Petroleum Geologists