Abstract: Seismic Response Interpretation for Heterogeneous Reservoir Models

Patrick Fichtl, Frederique Fournier

Seismic information is crucial to constrain the reservoir image between wells. However, in heterogeneous environments, it is often difficult to interpret the seismic response of the reservoir, especially with limited well control. Analyses of synthetic seismic responses of typical reservoir models are helpful for defining the geological information contained in the seismic data.

We propose a geological interpretation of seismic responses of various models in the frame of fluvio-deltaic deposits: The first model is the intermediate unit of the Mesa Verde outcrop, whose seismic response was computed by elastic wave modelling, after assignment of elastic parameters constant by lithofacies. The other models correspond to stochastic lithofacies simulations with different geostatistical characteristics. Their seismic responses were computed with ID modelling (convolution).

The geological interpretation carried out on those synthetic seismic data is based on a calibration of the seismic parameters in terms of probabilities of encountering the different lithofacies. The technique we use is a non parametric discriminant analysis. The seismic parameters are the amplitudes for the convolution models or impedances and reflection coefficients for the first model for which a post-stack stratigraphic inversion was carried out.

We compare the seismic derived lithofacies to the true ones to determine the potential of the seismic data for describing the reservoir heterogeneities. We use the different models to discuss:

- the impact of the spatial distribution of heterogeneities on the geological interpretation of the seismic data;

- the influence of the seismic lateral filtering on the interpretation;

- the influence of the number of wells, used in the interpretation, on the final results.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France