Risk Analysis and Prospectivity of Miocene to Recent Sediments in Parihaka Area, Taranaki Basin, New Zealand

Abstract

The Taranaki Basin is structurally complex and the only producing basin in New Zealand. The basin is under-explored compared to many failed rift complex basins of its size and there remains considerable potential for further discoveries. Recent structural inversion in the basin played a key role in the remigration of earlier trapped hydrocarbon, hence, the need to accurately locate and define trap volumes. This paper presents an integrated geological and geophysical approach in identification of prospects and risk reduction in Parihaka area, offshore Taranaki Basin. Direct hydrocarbon indicators (bright spots) and impedance inversion helped identify six potential targets in the Mangaa and Moki turbidite formations. These targets are located in structural traps which include roll over anticline, faulted anticlines related to a deep seated volcanic diapir, and fault traps in relay zones between segments of the Parihaka fault. A 7th target appears less viable because the bright spot is related to high-impedance lithology. Geologic reconstruction using a horizon flattening technique reveals that change in tectonic style throughout the history of the basin affected the petroleum system, especially the trapping and fluid migration pathways. Following the proper identification of potential targets, volume of in-place and recoverable reserves were estimated and a risk assessment was performed taking into account uncertainties in source rock, maturation, reservoir, seal, trap and migration timing. The result of risk assessment and volume estimation facilitated the ranking of targets and delineation of the top 4 drilling targets. The study shows that all elements of the petroleum system are in place in the Parihaka area.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016