New Zealand

Kora Oil Field

Located approximately 30 km north of New Plymouth and 30 km west of Awakino in the northern Taranki Basin, New Zealand, the Kora oil field is a 10 km to 12 km diameter, 1 km thick, subsurface, volcanic/plutonic complex (Russell, 1997; Bergman et al, 1992). The basement rocks range from Mesozoic granitoids, most abundant in the southern part of the basin, to Paleozoic forearc basin deposits.

Four wells were drilled at the Kora oil field. The Kora-1 wildcat exploration well was drilled between 1987 and 1988 to a depth of 3,450 m with the primary reservoir target in the Eocene/Oligocene Tangaroa Sandstone. Residual hydrocarbons were encountered in the Tangaroa and produceable crude oil was found between 1,790 m and 1830 m in the Upper Miocene volcanic interval. A further 3 wells (Kora-2, -3 and -4) were drilled to constrain the hydrocarbon distribution at Kora and encountered only residual hydrocarbons in the upper most volcanic rock intervals in Kora-2 and -3 (Bergman et al, 1992).

Bergman et al (1992) state that volcanic reservoirs are viable targets for hydrocarbon reservoirs in the northern Taranaki Basin. Based on observations at Kora, the most prospective volcanic reservoirs are those complexes more deeply buried in the axis of the Taranaki Basin where the development of a suitable seal and the existence of thermally mature Pakawau source rocks are most likely.