Effects of Properties in Seismic Data on Reservoir Characterization and Consequent Fluid-Flow Predictions When Integrated With Well Logs

Abstract

ABSTRACT A reservoir model was generated to quantify the enhancements in reservoir description resulting from the incorporation of seismically-derived information with well-based data and to study how the quality of the seismic data affects those reservoir descriptions. The reservoir model was created from 56 well logs with a predetermined spatial correlation using geostatistical techniques. A regular grid of traces was extracted from this model and transformed into 3D seismic surveys which were then inverted to produce acoustic impedance logs. Several seismic data parameters such as frequency bandwidth, waveform phase estimation error, and correlation coefficient between seismic and well data were varied to study their relative importance on reservoir description and subsequent flow results. These differing seismic datasets were finally integrated with the original well-log data again using geostatistical methods. Comparative fluid displacements were performed on all reservoir realizations using an all-purpose flow simulator to quantify the flow behavior differences. The results, based on breakthrough time and oil recovery predictions, show that even marginal increases in frequency bandwidth (e.g., increases of 10 Hz in the upper frequency) provide significant enhancements to the reservoir model. Also, estimation of waveform phase to within ±20° of the true value is shown to be sufficient to capture much of the interwell heterogeneity contributed by the seismic data and thus does not significantly affect fluid-flow results. Finally, even for correlation coefficients as low as 0.4, which initially was considered quite low, sufficient positive contribution from the seismic data still warrants integrating it with the well-log data.