Permeability Scalar from Seismic-Based Fracture Prediction

Abstract

The post stack seismic fracture prediction method consistently shows fractures that are similar to those indicated by well methods and therefore seismic can be used to detect natural fractures between wells. The confidence in the seismic fracture prediction method's ability to capture information about fracture in Carbonate reservoir has increased if the well data are accurately integrated. This paper describes an approach in characterizing fractured reservoir of upper Jurassic Carbonate using seismic structure attribute maps. The ultimate objective of this study was to attempt to map permeability scalar inter-well for the contribution to the simulation model and the subsequent development plan of an oil field offshore Abu Dhabi. The studied field is not developed, but the subject reservoir was sparsely sampled with logs, limited well tests, limited cores, one FMI and one full waveform sonic. We have studied and analyzed the well based fracture detection results. The well analysis included FMI study, Stoneley waveform, well production tests and core images. The likely fractured layers were identified at the lower dense part of the reservoir. Well seismic synthetics were generated and the fractured layers were found to exist in less than one cycle. Following the fractured layers identification in the seismic cube, an intensive seismic attribute analysis was conducted. The studied seismic reservoir attributes includes spectral decomposition analysis of Amplitude and Phase followed by structure attributes such as Coherency, Curvature, Amplitude change in X or Y and Azimuth. Here we report and analyze the fracture prediction results for Carbonate reservoir. A consensus results from borehole ellipticity, Seabed ramp and near Seabed seismic structure map versus known regional stress will be presented as guide of current stress direction. Based on the extracted fracture map from seismic, the current stress direction and the well permeability scalar, a 1km x 1km permeability scalar map was generated.