Closing the seismic resolution gap of fractures through seismic and image-log analysis, a North Sea case study

Abstract

The “seismic resolution gap” has been an area of ambiguity ever since the results of 3D seismic interpretation have been used as inputs for modeling purposes because many important structural events such as fractures are at or below seismic resolution, which can impinge reservoir properties such as porosity and permeability. Having the means to accurately map these events with confidence has always been a challenge. More often than not, localized mapping of these features at borehole conditions can be achieved by core or image-log analysis. Seismic-derived attributes have assisted in improving the interwell geologic understanding in a lateral sense, but they are always hampered by vertical resolution. Enhanced imaging, such as cyan-magenta-yellow blending of attributes, has helped improve the lateral understanding of fracture patterns and networks, as shown in this workflow, but the challenge with vertical resolution still persists. However, by combining borehole and seismic data studies in a distinct workflow, it has become possible to identify overlaps and misalignments, which in turn has assisted in identification of discrete structural patterns not previously identified because of the seismic resolution gap. These results will then be used to improve the confidence of structural interpretation and static fracture models, which all go toward improving reservoir simulation models and geologic understanding.