Abstract:
The Tajjal field is located in Lower Indus Basin, Pakistan, and the B-interval of
Lower Goru is the main reservoir of Cretaceous age. Variations in reservoir quality are the
main risk that depends on the number of properties. Porosity is one of the main properties
which was evaluated throughout the 3D seismic data cube of the field instead of well
location only, by adopting a multi-linear regression method and was later, used for
designed the reservoir property at well location by doing AVO analysis. In this integrated
approach for reservoir characterization, the petro-physical analysis was performed on three
wells drilled in the Gambat-Latif block. Tajjal-01 encountered a 9.9m hydrocarbon-bearing
zone with effective porosity of 6.38%, Tajjal-02 encountered a 5m hydrocarbon-bearing
zone with effective porosity of 12.87% and Tajjal-03 encountered a 4m hydrocarbonbearing zone with effective porosity of 8.21%. Then multi-attribute inversion was done
which displayed low impedance values dominantly for sands of B-interval data and showed
that there were least differences between the seismic data derived porosities and well log
derived porosities for the top sands’ layer. Hence, this was considered to have a dominant
impact on P-impedance. Lastly, AVO modeling was only done for Tajjal-01 well due to
data limitations and Class I & IV anomaly was found in top sands of B-interval. Hence,
top sands of B-interval were confirmed to have a good reservoir quality.
