Interpretation of Seismic Data in Terms of Gas Reservoir Identification (Carpathian Foredeep, SE Poland)
AGH University of Science and Technology, Department of Geophysics Krakow, Poland
The Carpathian Foredeep is a medium-sized siliciclastic basin filled with Miocene thin-layered sediments. Seismic surveys allowed to identify lots of hydrocarbons accumulations within the area. Unfortunately, not all seismic anomalies occurred not to be positive. The aim was to find whether there is a chance to distinguish between partial and commercial saturation on the basis of seismic modelings and advanced analyses.
Well log data such as compresional and shear wave velocities and density were used in construction of multivariant seismogeological models. Relationships between the mentioned parameters and gas saturation and porosity were determined using cross-plots of well logs. Fluid substitution was used to apply velocity corrections caused by gas saturation. Detailed analyses of both seismic and well log data allowed to assume several frequently observed reservoir geometries. Seismic offset modelings were used for generation of synthetic seismic data.
The investigations were mainly focused on pre-stack seismic data. The analyses included AVO attributes, lambda-mu-rho analysis and elastic inversion. Main problems in interpretation were connected with finding appropriate relations between seismic wave velocities and saturation. The additional considered problem was an influence of tuning effect connected with thin sandstones and gas-water contacts. Obtained theoretical results were carefully analyzed and compared with interpreted seismic profiles in the area what resulted in more accurate reservoir interpretation.
AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid