Integrated Seismic Interpretation along with Attributes and Post Stack Inversion, Petrophysical Analysis, Rock Physics based Facies Modeling, Full Wave Inversion based Velocity Model Building & 3D Survey Planning of Sinjhoro Area, Lower Indus Basin Pakistan.

Abstract

Sinjhoro is a developed field of Oil and Gas accumulations with structural and stratigraphic traps in the Lower Indus Basin. The present study pertains to integrated seismic interpretation along with attributes analysis and post stack inversion, petrophysical analysis coupled with rock physics techniques, velocity model building using horizon-based interpolation and full wave inversion. It also includes 3D seismic survey planning for future exploration. The data used for this research work consist of thirteen seismic lines along with velocity data and well logs of 4 wells. The seismic interpretation shows horst and graben structures bounded by normal faults. After time to depth conversion,using the velocity model, the true structural geometry is obtained in the form of depth sections. The horizons were identified using formation tops from wells and their depths were confirmed through correlation with synthetic seismogram generated from sonic and density logs. Crustal extension analysis has also been carried out on the depth section which indicates an extensional regime. Petrophysics is the one of the most reliable tools for the confirmation of the type of hydrocarbon and for marking the proper zone of the interest for the presence of the hydrocarbon through combination of different logs. Petrophysics and rock physics analysis along with facies modeling and empirical relations of logs are performed on the Chak 5 Dim South-01 well and zone of interest identified where the fluid saturations and porosities are calculated. Seismic velocities have been calibrated through borehole velocities from sonic logs and velocity model has been built using spatio-temporal as well as horizon-based interpolation algorithms and finally improved with full wave inversion. 2D synthetic seismic has been generated from these velocity models through convolution with a Ricker wavelet. The results indicate that horizon-based interpolation generates the best velocity model and therefore it is used in time to depth conversion. Post stack seismic inversion analysis has been carried out for better understanding of the behavior of impedance in the reservoir and seal rocks. In addition, AVA synthetic gathers have been generated which indicate class II type of gas sands. As part of the study a 3D seismic survey has been planned keeping in view the existing data to increase the probability of success for field development and reservoir characterization