Shipton Z.K.,University of Strathclyde |
Meghraoui M.,CNRS Institute of Earth Sciences |
Monro L.,University of Glasgow |
Monro L.,Oil Search Ltd
Geological Society Special Publication | Year: 2017
The Upper Rhine Graben (URG) is a seismically active tectonic structure in intraplate Europe. Large and moderate earthquakes have occurred along the URG in the past but no coseismic surface faulting has been reported so far. We investigated active faulting along the western edge of the northern URG and identified the 25 km-long linear Riedseltz-Landau normal fault scarp as a major tectonic structure affecting late Pleistocene and Holocene deposits. The fault zone is exposed in the Riedseltz quarry where it affects Pliocene sand and gravels and overlying late Pleistocene (Wurm) units. These units have not been buried deeper than a few tens of metres and yet the fault zone contains cataclastic deformation textures. Cataclasis is demonstrated by spalling and transgranular fractures in quartz grains concentrated in deformation bands with reduced grain size. The observed microstructures suggest multiple phases of deformation with cataclasis followed by emplacement of a prominent Fe-oxide matrix into deformation bands, and later emplacement of a clay-rick matrix into fractures. Previous geological and geophysical studies along the fault show late Pleistocene (Wurm) loess deposits (c. 24-10 ka before present) and early Holocene sand-silty deposits with individual or cumulative 1.5 and 0.7 m surface slip, respectively. Field observations and previous results from shallow geophysics provide a minimum 0.15 mm a-1 time-averaged slip rate. The Riedseltz fault parameters integrated in a dislocation model suggest a minimum Mw 6.6 earthquake as a plausible scenario in the northern URG. The observations of cataclasis in shallowly buried sediments coupled with observations of the late Quaternary fault scarp call for palaeoseismic studies that may document the occurrence of a larger earthquake on the western edge of URG. Surface faulting of young, shallowly buried sediments associated with cataclasis provides new evidence for assessing the occurrence of large earthquakes and seismic hazard assessment in the northern URG. © 2017 The Author(s).
Hill K.C.,Oil Search Ltd |
Lucas K.,Queen's University |
Lucas K.,Thunder Bay Regional Research Institute |
Bradey K.,Oil Search Ltd
Geological Society Special Publication | Year: 2010
Cross sections, seismic data and centrifuge analogue modelling reveal the structural styles in the oil-producing areas of the Papuan Fold Belt. They include inverted basement faults, detachment faults in the Jurassic section 1-2 km beneath the Neocomian Toro Sandstone reservoir, and tight, overturned folds in the reservoir sequence with stretched and boudinaged forelimbs, cut by break-thrusts. Additional features include highly variable thicknesses in the Cretaceous Ieru Formation, the regional seal sequence, including through-going detachments that isolate the overlying thick Miocene Darai Limestone. Centrifuge analogue modelling of intact, plane-layered strata determined that the mechanical stratigraphy and the thickness of weak beds above the lower décollement horizon exert the greatest control on the structural style. Large-offset thrust faults were only produced in models with pre-cut faults, generating early inversion and then large ramp anticlines, similar to those in the Kutubu Oilfield, which has reserves of .350 million barrels. It is suggested that the Kutubu Oilfield trend was underlain by a large normal fault and that, by analogy with the Vulcan Sub-basin, oil-rich source rocks may be confined to the hanging wall or north side of this fault. Oil would have been generated and expelled during thin-skinned deformation. © The Geological Society of London 2010.
Bailey B.T.,Macquarie University |
Bailey B.T.,Oil Search Ltd |
Morgan P.J.,University of Canberra |
Lackie M.A.,Macquarie University
Antarctic Science | Year: 2015
A gravity survey was conducted on the Windmill Islands, East Antarctica, during the 2004-05 summer season. The aim of the study was to investigate the subsurface geology of the Windmill Islands area. Ninety-seven gravity stations were established. Additionally, 49 observations from a survey in 1993-94 were re-reduced and merged with the 2004-05 data. A three-dimensional subsurface model was constructed from the merged gravity dataset to determine the subsurface geology of the Windmill Islands. The main country rock in the Windmill Islands is a Garnet-bearing Granite Gneiss. A relatively dense intrusive charnockite unit, the Ardery Charnockite, generates the dominant gravity high of the study area and has been modelled to extend to depths of 7-13 km. It has moderate to steep contacts against the surrounding Garnet-bearing Granite Gneiss. The Ardery Charnockite surrounds a less dense granite pluton, the Ford Granite, which is modelled to a depth of 6-12 km and creates a localized gravity low. This granitic pluton extends at depth towards the east. The modelling process has also shown that Mitchell Peninsula is linked to the adjacent Law Dome ice cap by an 'ice ramp' of approximately 100 m thickness. © 2016 Antarctic Science Ltd.
Eisemberg C.C.,University of Canberra |
Rose M.,Flora and Fauna International |
Yaru B.,Oil Search Ltd. |
Georges A.,University of Canberra
Biological Conservation | Year: 2011
Papua New Guinea has astonishing biological and cultural diversity which, coupled with a strong community reliance on the land and its biota for subsistence, add complexity to monitoring and conservation and in particular, the demonstration of declines in wildlife populations. Many species of concern are long-lived which provides additional challenges for conservation. We provide, for the first time, concrete evidence of a substantive decline in populations of the pig-nosed turtle (Carettochelys insculpta); an important source of protein for local communities. Our study combined matched village and market surveys separated by 30. years, trends in nesting female size, and assessment of levels and efficacy of harvest, each of which was an essential ingredient to making a definitive assessment of population trends. Opportunities for an effective response by local communities to these declines needs to consider both conservation and fisheries perspectives because local communities consider the turtle a food resource, whereas the broader global community views it as a high priority for conservation. Our study in the Kikori region is representative of harvest regimes in most rivers within the range of the species in Papua New Guinea, and provides lessons for conservation of many other wildlife species subject to harvest. © 2011 Elsevier Ltd.
Wilson P.,Corrosion Risk Management Pty Ltd. |
Hancock P.J.,Oil Search Ltd. |
Krouse D.,Callaghan Institute
NACE - International Corrosion Conference Series | Year: 2014
Non destructive Testing (NDT) is commonly used to assess the extent of corrosion within plant, including vessels, piping and pipelines. In particular measuring instruments using ultrasound are used to find locations where loss of wall thickness has occurred and to determine the extent of the loss. Inherent in the measurement of wall thickness is the assumption that from a limited set of measurements it is possible to infer the condition of a vessel, heat exchanger tube bundle or section of piping. The determination of corrosion rate then requires a reassessment of the wall thickness at a later date. For old plants, the variability in corrosion damage both in a spatial sense and in depth of loss causes a difficulty in finding the worst case losses in wall thickness and in determining remaining life. It is also necessary to recognize that the measurement error depends on the skill applied by the inspector during the inspection. This paper discusses the use of probability of detection concepts for finding corrosion damage and illustrates it for a corroding vessel inspected over a 2 year period. It also describes the use of distributions of wall loss to characterize the condition of corroding vessels and pipelines. The incorporation of statistical principles into data analysis is required because of the inherent variability of corrosion damage. © 2014 by NACE International.
News Article | November 17, 2016
Santos Ltd., Adelaide, has signed a farm-in agreement with ExxonMobil Corp. and Oil Search Ltd. to take a 20% interest in Papua New Guinea highlands permit PPL 402.
News Article | September 13, 2016
Oil Search Ltd., of Sydney and Port Moresby, has refocused its attention offshore in the Gulf of Papua in a bid to explore areas with potential to support the company’s expanding LNG portfolio. Its Papua New Guinea LNG (PNG LNG) joint-venture partner, ExxonMobil Corp., also has joined the project.
Zahirovic S.,University of Sydney |
Matthews K.J.,University of Sydney |
Flament N.,University of Sydney |
Muller R.D.,University of Sydney |
And 3 more authors.
Earth-Science Reviews | Year: 2016
The breakup of Pangea in the Jurassic saw the opening of major ocean basins at the expense of older Tethyan and Pacific oceanic plates. Although the Tethyan seafloor spreading history has been lost to subduction, proxy indicators from multiple generations of Tethyan ribbon terranes, as well as the active margin geological histories of volcanism and ophiolite obduction events can be used to reconstruct these ancient oceanic plates. The plate reconstructions presented in this study reconcile observations from ocean basins and the onshore geological record to provide a regional synthesis, embedded in a global plate motion model, of the India-Eurasia convergence history, the accretionary growth of Southeast Asia and the Tethyan-Pacific tectonic link through the New Guinea margin. The global plate motion model presented in this study captures the time-dependent evolution of plates and their tectonic boundaries since 160 Ma, which are assimilated as surface boundary conditions for numerical experiments of mantle convection. We evaluate subducted slab locations and geometries predicted by forward mantle flow models against P- and S-wave seismic tomography models. This approach harnesses modern plate reconstruction techniques, mantle convection models with imposed one-sided subduction, and constraints from the surface geology to address a number of unresolved Tethyan geodynamic controversies. Our synthesis reveals that north-dipping subduction beneath Eurasia in the latest Jurassic consumed the Meso-Tethys, and suggests that northward slab pull opened the younger Neo-Tethyan ocean basin from ~ 155 Ma. We model the rifting of ‘Argoland’, representing the East Java and West Sulawesi continental fragments, as a northward transfer of continental terranes in the latest Jurassic from the northwest Australian shelf – likely colliding first with parts of the Woyla intra-oceanic arc in the mid-Cretaceous, and accreting to the Borneo (Sundaland) core by ~ 80 Ma. The Neo-Tethyan ridge was likely consumed along an intra-oceanic subduction zone south of Eurasia from ~ 105 Ma, leading to a major change in the motion of the Indian Plate by ~ 100 Ma, as observed in the Wharton Basin fracture zone bends. We investigate the geodynamic consequences of long-lived intra-oceanic subduction within the Neo-Tethys, requiring a two-stage India-Eurasia collision involving first contact between Greater India and the Kohistan-Ladakh Arc sometime between ~ 60 and 50 Ma, followed by continent-continent collision from ~ 47 Ma. Our models suggest that the Sunda slab kink beneath northwest Sumatra in the mantle transition zone results from the rotation and extrusion of Indochina from ~ 30 Ma. Our results are also the first to reproduce the enigmatic Proto South China Sea slab beneath northern Borneo, as well as the Tethyan/Woyla slab that is predicted at mid-mantle depths south of Sumatra. Further east, our revised reconstructions of the New Guinea margin, notably the evolution of the Sepik composite terrane and the Maramuni subduction zone, produce a better match with seismic tomography than previous reconstructions, and account for a slab at ~ 30°S beneath Lake Eyre that has been overridden by the northward advancing Australian continent. Our plate reconstructions provide a framework to study changing patterns of oceanic circulation, long-term sea level driven by changes in ocean basin volume, as well as major biogeographic dispersal pathways that have resulted from Gondwana fragmentation and accretion of Tethyan terranes to south- and southeast-Eurasia. © 2016 Elsevier B.V.
Sullivan S.,Oil Search Ltd |
Rowse J.,Oil Search Ltd
Society of Petroleum Engineers - SPE Asia Pacific Oil and Gas Conference and Exhibition 2012, APOGCE 2012 | Year: 2012
Operational conditions in the remote highlands of Papua New Guinea bring a multitude of challenges including complex geology, steep jungle terrain, extreme rainfall, a sensitive ecosystem, a variety of landowner cultures, ageing facilities, mature reservoirs, and fraught logistics. These factors conspire to increase the complexity of production forecasting well beyond just reservoir performance. After missing production targets for a number of years, a significant improvement in forecasting was needed to fully capture the uncertainties, both identified and unforseen. A probabilistic forecasting tool using Monte Carlo simulation has been developed which incorporates assessments of all major variables and takes account of historical performance and system changes. Successful implementation has resulted in the generation of realistic targets which have been met within four per cent for three years. Further, a clearer understanding of potential threats and opportunities combined with their impact on production has been achieved. These results have delivered material benefits to business planning, decision making and company reputation. Data to be presented on the forecasting tool will describe the quantification of uncertainty for each major variable including reservoir and facility performance, incremental production opportunities, project schedules and major unplanned downtime. This approach could be applicable to E&P companies operating in difficult conditions worldwide, where unreliable production targets have a major business impact. It is flexible enough for both short and long term forecasts, tracking and reporting, and adaptation to new or changed operating conditions. Copyright 2012, Society of Petroleum Engineers.
News Article | December 8, 2015
Woodside Petroleum Ltd. has called off its $11.6 billion (Aus.) bid to acquire Oil Search Ltd.