Geodetic And Vertical Datums Used in Papua New Guinea – An Overview

Abstract

The resource sector in Papua New Guinea uses a diverse selection of geodetic datums, coordinate reference systems, map projections and vertical (height) systems at all levels of company operations. The aim of this presentation is to provide a practical overview of these systems and is focused at GIS professionals, database managers, civil works managers and subsurface engineers. The PNG Oil and Gas Act still proscribes the geodetic datum used for petroleum operations in PNG. Currently, the Australian Geodetic Datum 1966 (AGD66) defined by the Bevan Rapids origin (NW of Kerema) is mandated by the Act. Consequently, spatial reporting of leases, well locations and other data are required by the Department of Petroleum and Energy (DPE) to be submitted in AGD66. The current PNG national geodetic datum gazetted by the PNG Lands Department is PNG94 and is somewhat different being a geocentric frame offset from AGD66 by approximately 200 m. The coordinates of PNG94 are fixed at the 1st January 1994 (reference epoch) and ignore any tectonic motion or earthquake deformation after that time. Global reference frames used by GNSS/GPS positioning use a kinematic global frame currently the International Terrestrial Reference Frame (ITRF) and closely related WGS84. Coordinates of ground features in these frames move continuously by several centimetres a year due to plate tectonics. In some instances, coordinates and elevations can change by metres after large earthquakes. Transformations between these geodetic datums and reference frames can be a complex exercise if the software used is not configured or customised properly or if metadata is absent. Some common pitfalls and resolutions are discussed. The diverse nature of height datums in PNG are also summarised. The main height datum used is Mean Sea Level (MSL), however the geoid models used to determine heights using GPS techniques in remote locations vary considerably in resolution and precision. This can lead to large inconsistencies in civil projects and resource modelling.

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