Abstract:
For the exploration of hydrocarbons, petrophysical analysis has been done in
Tolanj-01 well in Khushalgarh block Upper Indus Basin Pakistan. In Tolanj-01 drilling has
been done from Kohat Formation of Eocene age up to Samana Suk Formation of Jurassic
age. Logging suits including caliper log, spontaneous potential log, spectral gamma ray
log, computed gamma ray log, dual laterolog, microspherically focused log, neutron log,
density log and sonic log have been run from depth of 7740 ft to 10120 ft. Two zones have
been marked from 7980 feet to 8094 feet in Lockhart Formation and 8598 feet to 8682 feet
in Hangu Formation respectively, on the basis of calculated petrophysical parameters i.e.
low GR log values, high LLd values and neutron-density crossover. Both the marked zones
have low volume shale, low effective porosity and low hydrocarbon saturation that is why
it is showing low hydrocarbon potential. Identification of lithology and mineralogical
composition have been done with the help of M-N, neutron-density, neutron-sonic cross
plots and PEF log and it was found that the lithology of Lockhart Formation is limestone
having calcite and some dolomite minerals whereas lithology of Hangu Formation is
Sandstone. GR log is indicating the lithology of the Lockhart formation is pure limestone
at upper part having no organic matter and showing oxidizing environment of deposition,
whereas shaly to pure limestone at lower part, having the organic matter and reducing
environment of deposition. In Hangu Formation GR log is indicating the lithology of
formation is dirty at upper part and pure at the lower part which is marked as hydrocarbon
zone.
