Hydrocarbon prospectivity of the miocene-pliocene clastic reservoirs, Northern Taranaki basin, New Zealand: integration of petrographic and geophysical studies

Abstract In this study, it is aimed to characterize the Early pliocene sandstone (EP-SD) and Late Miocene-Early Pliocene Mangaa reservoirs efficiency of their sealing cap rocks using petrographical petrophysical data these zones in northern Taranaki basin, New Zealand. The prospective potential were studied impregnated thin sections, XRD analysis, well log (self-potential, gamma-ray, sonic, density, neutron, shallow\deep resistivity PEF) reservoir zones, addition Mercury intrusion capillary pressure (MICP) check some seals. EP-SD units are typically poorly consolidated very fine siltstone, with porosities averaging 25%. sands composed quartz (38.3–57.4%), common feldspars (9.9–15.2% plagioclase, 2.7–6.3% K-feldspars) up 31.8% mica. Albacore-1 north Basin, formation includes three separate for each (EP-SD1, EP-SD2, EP-SD3), sequence (Mangaa-0, Mangaa-1, Mangaa-2). section studies indicate that, samples grouped into greywackes, arenites siltstone microfacies much lithic fragments feldspars, sometimes glauconite pellets. From data, achieved that mineral composition dominated by quartz, mica/illite, chlorite. investigation revealed absence pay presence zone net thickness 5.79 m hydrocarbon saturation about 25.6%. effective vary between 23.6 27.7%, while shale volume lies 12.3 16.9%. Although content relatively low, high API (50–112 average 75 API) contributed K-feldspar intercalations muddy beds. Sealing include intra-formational seals within sequence, mudstones grained overlying further mudstones, shallower units. indicates capability trap 16.4–40.6 gas or 17.4–43.0 oil which low correlation central parts Basin Overlying primary seals, Giant Foresets Formation provide additional regional seal.