ABSTRACT: Scenarios of Oil and Gas Migration into the Maui Field, Taranaki Basin, New Zealand
Funnell, Robert H.1, S.D. Killops1, P.R. King2,
V.M. Stagpoole2, A. Nicol2, D. Darby2, P.G. Scadden2,
R.A. Wood2, R. Sykes1, and X. Zhan2
(1) Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand
(2) Institute of Geological and Nuclear Sciences
The oil and gas/condensate Maui Field lies in the Taranaki Basin about 40km off the west coast of the North Island, New Zealand. The field consists of two broad anticlinal closures formed by Miocene compression, and structurally enhanced by Pliocene normal faulting to the east. Recoverable reserves for the Maui Field were estimated at 3.6 Tcf gas and 180 MMbbl oil and condensate. Hydrocarbons are reservoired within stacked marginal marine-terrestrial sandstones of Paleocene to Eocene age. Taranaki Basin, Late Cretaceous, coal-sourced oils exhibit high pristane:phytane ratios, abundant hopanes, land-plant-derived terpanes, and are relatively depleted in steranes. However, Maui oils can be distinguished from other Taranaki Basin oils by their plant-derived triterpane distributions and isotopic composition. Maui gases consist of ~85% methane and 3He/4He ratios, indicated by a RMRA ratio of 3.4, suggest a mantle component may be present. The charge history of the Maui Field has long been uncertain. Four possible oil and gas migration routes from potential kitchen areas are investigated. Multi-1D models are used to reconstruct the timing and distribution of hydrocarbon generation and primary expulsion from Late Cretaceous coals. A combination of ray tracing techniques, use of a Shale Gouge Ratio for fault permeability, and 2D models along identified migration routes are presented to examine the various reservoir charging scenarios. Significant factors in the charge of the Maui Field include: multiple kitchens for hydrocarbon generation, fault plane permeability, and sequential filling of stacked reservoir compartments.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia