Abstract:
The objectives of this research were porosity distribution and differentiation of
different types of fluids in reservoirs. From well log data of Nandpur-02, potential
reservoir formations were identified. The formations of interest were Ranikot
Formation, Lumshiwal Formation, and Samana Suk Formation. These target formations
were then identified and marked on the 2D seismic data of Nandpur area through
synthetic seismogram of Nandpur-02 for delineation of subsurface structure. There was
a normal fault disturbing the area and is trending north-east to south-west and strata is
dipping towards north-west. Petrophysical analysis was performed on the target
formations to identify their reservoir properties. The hydrocarbon saturation was about
57 % in Nandpur-02 well for Lumshiwal Formation also having the porosity 9.6 %.
Then seismic inversion was performed, which develops a linkage between the seismic
data and the interpreted reservoir properties from well logs. Post-stack seismic
inversion (model-based inversion) was used to estimate reservoir characteristics from
seismic data such as acoustic impedance. The reservoir parameters, as well as
fundamental variables such as impedance of the target Formations, were delineated
using post-stack seismic data and well log data of the study area. Inversion model
showed low to moderate impedance values for Lumshiwal and Ranikot Formations.
The rock physics develops a relationship between the elastic properties from seismic
data (impedance) and the elastic properties calculated from well logs such as vp\vs
ratio. These elastic properties were then calculated and plotted using the Gassmann
equation. Cross plots of vp\vs ratio vs impedance, impedance vs porosity and vp\vs vs
porosity were made for the differentiation of fluid types in the reservoir zones. All these
cross-plots shows the presence of gas at certain reservoir level by showing low velocity
and impedance values along with good porosity. Results showed that Lumshiwal
Formation in Nandpur area has significant reservoir characteristics.
