Date of Graduation

8-2018

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

McGilvery, T.A. "Mac"

Committee Member

Milligan, Steve

Second Committee Member

Liner, Christopher L.

Keywords

Facies Mapping; New Zealand; Rakopi Formation; Source Rock; Taranaki Basin; Taranaki Delta

Abstract

The Taranaki Basin is located off the coast of the north island of New Zealand and is currently the only producing basin in New Zealand. Hydrocarbon accumulation in the Tui, Maari, and Maui fields is sourced to the Late Cretaceous and Paleogene units. Exploration of these units has extended from the continental shelf of the Taranaki Basin into the deep-water to the northwest. The Romney 3D survey and Romney–1 well are some the first public exploration projects to supply data from this area. The objective of this study is to estimate source rock quality and distribution of the Rakopi Formation in the Romney 3D survey utilizing seismic facies analysis, log motif, and geochemical evaluations.

The Rakopi Formation records the northwest prograding megasequences of the Taranaki Delta. Seismic facies are defined by internal reflection configuration, reflection amplitude, frequency, continuity, and boundary relationships found in these sequences. Specific depositional environments are interpreted and calibrated using gamma ray log motif and biostratigraphy. These were used to generate paleogeographic reconstructions illustrating areas with the best source potential within the Rakopi Formation. Although seismic stratigraphy does not quantify source rock quality, higher quality organic-rich facies are identified based on geochemical analysis and tied to specific intervals on the Romney–1 well.

The results of this study confirm primary source potential from type II/III, oil and gas prone non-marine coal-rich facies. This source interval contains type II kerogen with excellent total organic content, hydrogen index above 300, and above average generative potential. A potential secondary type I, oil prone, marine algal source facies may also be preserved in the far northwest portion of the Romney 3D and extend westward beyond the survey.

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