Petrology and reservoir quality of the Moki Formation in Cardiff-1, PPL38707, Taranaki Basin, New Zealand.

10 core pieces from the Moki Formation in Cardiff-1 (PPL38707) were petrologically analysed by thin section. Five were analysed by x-ray diffraction and scanning electron microscopy. The sandstones are fine - very fine grained, moderately sorted litharenites, with their detrital mineralogy indicating a predominantly low grade regional metamorphic sediment source with some sedimentary and igneous contributions. The clay minerals are chlorite and illite with minor kaolinite. Compactional deformation of lithic grains and the formation of authigenic calcite cement are important diagenetic features, causing a loss in porosity. Minor diagenetic processes are authigenic clay formation and quartz overgrowth development. The sands generally retain good intergranular porosity.