Hydrocarbons’ Putting on a Show! – Development of a PNG Shows Database

Abstract

In Papua New Guinea (PNG) in 2013, an anniversary slipped by unnoticed and uncelebrated! It marked a century since the Upoia 1 bore was drilled in the Papuan region of what has become Papua New Guinea. Since that time, 652 exploration wells have been drilled by numerous operators. Oil field practices have seen considerable evolution through the same period in two key areas for this study: drilling technology and charge (source, maturity, expulsion and migration of hydrocarbons). PNG’s Papuan Basin (PB) has a proven petroleum system with the dominant hydrocarbon source interval being of Jurassic age. Associated oil and gas accumulations in the basin have been commercially exploited since the early 1990’s: many of these pioneer fields are now off plateau and in an advanced state of natural decline. PNG’s Eastern Fold Belt (EFB) is a much more lightly explored region. The discovery of the Antelope gas field has demonstrated that the EFB’s previously proven, but poorly understood Late Cretaceous to early Tertiary Petroleum System, has generated commercial quantities of hydrocarbon. It also appears that there is a younger Cenozoic source rock in the Eastern Papuan Basin. The early exploration of both petroleum systems was built on observed surface seeps which encouraged geophysical surveys, prospect delineation and drilling. The reports from early exploration activities provide an often-overlooked reference set with wonderfully detailed descriptions of observed hydrocarbons. This paper describes an ongoing project in which we have systematically reviewed and catalogued over a hundred years’ worth of hydrocarbon shows from wells that are captured in a database using a standardized show classification system developed by Oil Search’s geochemistry consultant, Dr Andrew Murray. The classification system enables the geoscientist to categorize shows into eight (8) groups: (1) Hydrocarbon flow tested to surface (2) Hydrocarbons recovered to surface in wireline tools, (3) Hydrocarbons indicated from good multi-point and pressure gradients, (4) Hydrocarbons indicated from electric logging tools (FEWD/Wireline), (5) Hydrocarbons recovered from, or observed in, core barrels, (6) Hydrocarbons observed during mudlogging, (7) Hydrocarbons recovered from, or observed in, Side Wall Core (SWC), and (8) Hydrocarbons recovered from, or observed in, cuttings. After being categorized, the shows are then awarded confidence scores based on the strength of the supporting data. While this process is ongoing, data is progressively being integrated into regional 3D basin models, these models rely on the shows database for calibration. In the software, show data is displayed in conjunction with seismically derived depth converted surfaces. The modelled hydrocarbon generation, expulsion and migration is then calibrated using the recorded shows, with their presence being described by the models in both space and time (4D space). In combination digital hydrocarbon show data along with software derived geospatial displays enables rapid visualization, assisting explorers as they seek to identify new patterns, seek to priorities focus areas and test potential migration pathways: they provide a calibrated predictive tool to assist explorers risk hydrocarbon charge.

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