Information on fault orientation from unoriented cores

Unoriented core data can be integrated with other data types, such as seism ic data, dipmeter data, and stratigraphic isochore or isopach data, to prov ide a unique solution for bedding orientation. In addition, such an integra ted approach will help to identify erroneous data and interpretations. Once a unique solution for bedding orientation is obtained, this information ca n be used to find the orientation of faults and deformation bands as observ ed in core data. Although larger scale faults commonly are difficult to cor e due to brecciation and poor coherency of the fault rock, structural studi es demonstrate that faults (with discrete slip surfaces) in sandstones are associated with numerous deformation bands in damage zones that are typical ly several meters wide. Within the fault zone itself, the deformation bands commonly are subparallel to the larger scale fault. Analyses of the orient ation of deformation bands within the fault zone thus may yield information on the orientation of the larger scale fault. Based on such an integrated approach, it is possible to find information on faults on a subseismic scal e that would otherwise be difficult or impossible to obtain. Quality contro l against seismically resolvable faults from the Gullfaks field, northern N orth Sea, demonstrates that this simple approach is valid and can provide i mportant additional information for the structural interpreter. The results can be used to optimize well planning and enhance the understanding of flu id flow patterns in the reservoir.