Seismic Models of the Barik Reservoir

Abstract

Seismic modeled responses for known geological models, often using well logs, help interpret field seismic data for reservoir characterization. The seismic response of the Barik reservoir is investigated based on its properties as revealed by well logs. The porous Middle Barik manifests itself on the synthetic seismic data within the relevant bandwidth of the available seismic. In the Extended Elastic Impedance domain, chi projections of +30 and -60 appear to separate sand from shale lithology, and relatively high from low porosity in the Barik reservoir, respectively. Various models of the Barik reservoir are also built. These include ones with varying rock properties, thicknesses, and porosity. In the models with varying rock properties, the AVO signature of the Barik sand changes from class IV when the change in Vp/Vs ratio at the interface is weak, to class II or III in other cases. Effects of changes in fluid type are negligible, although a gas charged Barik sand exhibit strong AVO intercept and gradient amplitudes. The AVO behavior of the Barik sand is also dependent on its thickness. A thicker Barik sand shows class IV AVO with a strong negative intercept and positive gradient, whereas one that is half as thick displays class II AVO with a weak negative intercept and negative gradient. The porosity of the Barik sand influences its AVO behavior. The insitu and relatively low porosity Barik sand show class IV AVO with a sharply decreasing gradient for tighter Barik, whereas a higher porosity Barik sand showed a stronger gradient. Lastly, the frequency-dependent AVO signature of the Barik reservoir is investigated. The analysis revealed that the fluid signature is indistinguishable at 20 Hz but may be distinguished at 30 Hz.