1963 Paper B

CONSTRUCTION OF POROSITY, Rwa, Rw, WATER SATURATION, PERMEABILITY AND TRAVEL TIME VERSUS RESISTIVITY PLOTS BY THE IBM 704 COMPUTER

David R. Matuszak

Pan American Petroleum Corporation Tulsa, Oklahoma

ABSTRACT

The IBM 704 computer program discussed here is designed to provide rapid and thorough quantitative analysis of selected intervals using resistivity and continuous velocity log data. Minimum data input for the computer program consists of true resistivity and travel time from which a travel time versus true resistivity plot may be automatically obtained.

If additional input information is supplied, the following computer output may be obtained:

1. Porosity (Ø) based on solution of the Wyllie time-average equation
2. Water saturations of the flushed or invaded zone (Sxo or Si) and the uninvaded zone (Sw) based on the Archie saturation equation
3. Ratio of apparent fluid resistivity to known water resistivity (Rwa/Rw)
4. Ratio of apparent formation factor to sonic formation factor (Fr/Fs) where Fs is computed from either the Humble or Archie equation
5. Permeability (k) computed from k=-[cس/Sw]2
6. Plots of travel time versus Ri or Rxo

Sw, Si or Sxo, Rwa, Rw, f and k are presented both as a printed list and as a graphical plot against depth for direct correlation with the induction and sonic log curves. Comparison of the computed values for all selected intervals provides a relative indication of porosity, permeability, movable oil, and hydrocarbon saturation. Comparison of Sw with Si or Sxo may indicate the presence of a salt water annulus.

The principal advantages of the program lie in the simplicity and flexibility of the data input requirements, the graphical output, and its potential adaptability to automatic processing of digitized logs. Additional refinements may be added as warranted.