The Groningen gas field is the largest gas field in Europe and has been showing seismicity since the 1990s. The ~200 meter deep gas reservoir is situated at ~3 km depth, and comprises Permian (Slochteren) sandstone from the Rotliegend formation. The reservoir has been cored extensively by the field operator, the Nederlandse Aardolie Maatschappij (NAM). This dataset constitutes photographs of core slabs (core-parallel slices) taken from the reservoir intervals of 67 cored wells in the...