Measurements and interpretation of well logs in the Jeziórko sulphur deposit, Tarnobrzeg, Poland

Abstract

Geophysical logs of borehole F-380 drilled through the Jeziórko sulphur deposit near Tarnobrzeg arc interpreted in terms of mineral composition and porosity. Measurements were made from a standard set of logs by Geokar Geophysical Co. and from using university prototype logging equipment developed for shallow boreholes. Comparative analysis was made of GR and gamma ray spectroscopry, density, neutron-gamma, epithermal neutron, and acoustic logs. The interpretation yielded values for the volume of limestone, clay mineral content, sulphur content, and porosity while the barite content in the sulphur deposit was determined from a four-log set (GR, neutron-gamma, density, and acoustic). A gamma ray log with the uranium window subtracted, GRS, used instead of GR, gave the distinct drop of shaliness and caused the distinct changes of sulphur content for selected intervals of the section examined. To test the geophysical interpretation, the sulphur content of core samples of limestone was determined by three different techniques: ICP-AES analysis, sample combustion in the LECO automatic analyser and X-ray phase analysis. Clay mineral identification in the overburden was attempted using the TR vs. K cross-plot. Acoustic full wavetrains were used for rapid identification of formation zones with different clastic parameters. The dynamic coefficient of rock clasticity, i.c. the Poisson coefficient, was obtained from P-wave and S-wave velocities, determined in situ from acoustic full wavetrains.