Abstract
Recent improvements in land seismic data quality have made it possible to initiate lithostratigraphic interpretations of deep (4000-5000 m; 2.2-2.8 s) subsalt Permo-Carboniferous gas reservoirs in the Northwest German Basin. The first modeling and interpretation results indicate that the reflection character of Permian reservoir dolomites and sandstones can be interpreted to predict lithology and porosity variations using reflection character analysis. These formations are commonly thick enough to be resolved (>20 m) and typically have velocities 1000 to 2000 m/s slower than overlying and underlying nonreservoir rocks.Deeper Upper Carboniferous reservoir sandstones occur within a discontinuous low-amplitude seismic facies which can be clearly differentiated from a continuous high-amplitude facies formed by the less prospective Upper Carboniferous coal measures.The accuracy of Permian reflection character interpretations is dependent on the availability of high-frequency, zero-phase, relative amplitude seismic data. New 3-D data are appropriate but of limited availability. To provide suitable 2-D data, wavelet processing of selected variable vintage lines was completed. More routine use of wavelet processing and lithostratigraphic interpretation methods should help to better define reservoir facies and stratigraphic traps, lower prospect risk, and increase success ratios.
