Palaeogeographic and Palaeoclimatic evolution of Papua New Guinea: The Role of Palaeo-Earth Systems Models and Palaeo-tidal Models in Mapping Source Facies and its implications for new plays

Abstract

The distribution of source rock environments and the lateral variation in source quality are significant uncertainties for exploration, particularly in little explored and frontier basins, such as eastern and northern Papua New Guinea. The tectonic and palaeogeographic development of New Guinea records Jurassic extension, Cretaceous subsidence, followed by Cenozoic uplift, subsidence and compression. Known source rocks, derived from published datasets, demonstrate a northwest-southeast trend, extending from the onshore Papuan Fold Belt, out into the Gulf of Papua. Onshore western Papua New Guinea, Jurassic sequences are the likely source rocks, comprising the early-rift terrestrial Magobu Formation and the later syn-rift marine shelfal sediments of the Barikewa, Koi-Iange and Imburu Formations. Throughout the Lower Cretaceous, intermittent regressive fluvio-deltaic packages represent some of the major reservoir units within the Papuan Fold and Thrust Belt (PFTB). However, marine transgressions led to the deposition of marine siltstones, mudstones and shales of the Ieru, Chim and Maril Formations, which are considered as potential hydrocarbon sources across western Papua New Guinea. Within Papua New Guinea, onshore and offshore seeps have demonstrated a working petroleum system and the possible extension of these known source rocks, and/or the addition of alternative source rock systems, which could be critical for future exploration. Modelling the process of organic matter productivity, dilution and preservation to predict the distribution of source rock environments requires understanding of the palaeogeographic setting and climatic and oceanographic parameters. These have been derived using deformable Plate Kinematics reconstructions, global data-constrained palaeogeographic mapping, state-of-the-art palaeo-Earth systems and an unstructured mesh model to simulate palaeotides. This allows the definition of source facies depositional space for marine source rock environments that developed during the evolution of Papua New Guinea. This approach also develops our understanding of the regional palaeogeographic and palaeoclimatic geohistory, including drainage basin evolution and the quantification of clastic sediment flux. The gridded model results provide an objective assessment of lateral variability in source quality for key source rock horizons and enables development of new play concepts that can be assessed in the context of complimentary data sets such as known hydrocarbon occurrences, seeps or DHIs.

AAPG Datapages/Search and Discovery Article #90371 © 2020 AAPG Asia Pacific Region, The 1st AAPG/EAGE PNG Geosciences Conference, PNG’s Oil and Gas Industry: Maturing Through Exploration and Production, Port Moresby, Papua New Guinea, February 25-27, 2020