Hydrocarbon generation modeling and source rock characterization of the Cretaceous-Paleocene Taratu Formation, Great South Basin, New Zealand

Hydrocarbon generation modeling and source rock characterization have been carried out on rock samples of the Taratu Formation in the Great South Basin, New Zealand. The Paleocene and Late Cretaceous Taratu Formation samples from Tara-1 well are utilized for geochemical studies. Rock-Eval pyrolysis results show that Taratu formation accommodates organic matter of excellent quantity and quality, with proliferous kerogen type II-III (oil and gas prone) and minor kerogen type III (gas prone). Hydrogen index (HI) of this formation ranges from 165.0 to 327.5mg HC/g TOC and only Late Cretaceous source rock samples are thermally mature, with maximum pyrolysis temperature (T-max) up to 459 degrees C and vitrinite reflectance (% R-o) from 0.40 to 1.15% R-o. One-dimensional basin modeling shows a best fit in a calibration of measured and modeled temperatures and vitrinite reflectance. The top of oil window was encountered 51Ma ago at 3100m and gas generation took place at 4132m in 8Ma ago.