Abstract

Reservoir Characterization of a heterogeneous reservoir like Kalol pays in Wadu-Paliyad field has been a big challenge due to presence of coal layers which has large impact on seismic amplitudes. It was observed that high amplitude contrast due to coal layers was masking the signature of reservoir unit. In addition to that discrimination of reservoir and nonreservoir at log scale and seismic scale based on pimpedance and Vp/Vs was also difficult due to overlap of these properties. To overcome this problem and address uncertainty involved in deciphering pay sand distribution of Kalol formation, Pre stack Geostatistical Inversion (GI) was carried out. The present paper deals with K-IX sand in the eastern part of Wadu-Paliyad field. The main challenge in this part was to find suitable areas for further development as nearby wells were already water flooded due to Water Injection (WI). A synergistic approach combining GI, exponential decline method and well performance analysis was adopted to reduce the uncertainty. In this work, we have applied constant-pressure solution of the diffusivity equation for a closed, circular reservoir in the form of an exponential decline equation to estimate drainage radius of the wells and permeability of pays in the prospective areas to identify unexploited areas. Few development locations already drilled based on this study have shown encouraging results both in well log and production performance.