Browsing by Author "Langendam, AD"

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    Meteorites on the Nullarbor Plain, insights from synchrotron powder diffraction
    (Universities Space Research Association, 2019-03-19) Brand, HEA; Langendam, AD; Whitworth, AJ; Alkemade, SL; Mitchell, JT; Davis, A; Stephen, NR; Tomkins, AG
    Introduction: The Australian deserts are an excellent place to search for meteorites, the dry warm climate limits changes on the surface allowing meteorites to remain in place for hundreds, if not thousands of years. Additionally, the Nullarbor plain – one of the largest limestone karst systems in the world provides an additional benefit in colour, the light limestone contrasting the black meteorites well. Over the past decade a group from Monash have been searching for these meteorites and with moderate success have collected over 200 new meteorites. This represents approximately 1/5 of Australia’s meteorite collection. Although the Nullarbor provides a fairly stable environment, there are still variations in the weathering of these meteorites and it is important to establish if this is just a result of time on the surface or if there is also a location and local environment factors. While these meteorites have been studied using optical and SEM techniques, synchrotron XRD (SXRD), represents a fast way to gain detailed bulk mineralogy of these samples to complement and add to the existing data. It can also be combined with geo-spatial data associated with the samples to model and determine weathering patterns for the meteorites on the Nullarbor. To this end we plan to study a wide selection of Australian Meteorites of various classes using SXRD to determine the phases present, with particular sensitivity to minor phases, both original and weathered mineral phases. Fig. 1. Context image to show meteorite collection sites. The meteorites described here are a mixture of officially described meteorites and new, as yet, unclassified meteorites from the Nullarbor as well as having a range of compositions. The samples were chosen as being a large enough sample, or multiple fragments, so that a representative sample (~0.5g) could be crushed while leaving enough for other analyses. Figure 1 shows the collection area for these meteorites. The meteorites which are not officially classified have been named for the date they were found (DDMMYY) and then alphabetically for the order they were found that day.
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    Naturally occurring radioactive materials in offshore infrastructure: understanding formation and characteristics of baryte scale during decommissioning planning
    (Elsevier, 2024-03-05) MacIntosh, A; Oldfield, DT; Cendón, DI; Langendam, AD; Howell, NR; Howard, DL; Cresswell, T
    Contaminants, including naturally occurring radioactive material (NORM) of the 238-uranium and 232-thorium decay series, have been recognized as a global research priority to inform offshore petroleum infrastructure decommissioning decisions. This study aimed to characterize pipeline scale retrieved from a decommissioned subsea well tubular pipe through high-resolution elemental mapping and isotopic analysis. This was achieved by utilizing transmission electron microscopy, Synchrotron x-ray fluorescence, photostimulated luminescence autoradiography and Isotope Ratio Mass Spectrometry. The scale was identified as baryte (BaSO4) forming a dense crystalline matrix, with heterogenous texture and elongated crystals. The changing chemical and physical microenvironment within the pipe influenced the gradual growth rate of baryte over the production life of this infrastructure. A distinct compositional banding of baryte and celestine (SrSO4) bands was observed. Radioactivity attributed by the presence of radionuclides (226Ra, 228Ra) throughout the scale was strongly correlated with baryte. From the detailed scale characterization, we can infer the baryte scale gradually formed within the internals of the tubular well pipe along the duration of production (i.e., 17 years). This new knowledge and insight into the characteristics and formation of petroleum waste products will assist with decommissioning planning to mitigate potential radiological risks to marine ecosystems. © 2024 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
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    To leave or not to leave: a tiered assessment of the impacts of scale residue from decommissioned offshore oil and gas infrastructure in Australia
    (ICRP, 2025-11-06) MacIntosh, A; Cresswell, T; Koppel, DJ; Hirth, GA; Tinker, R; Dafforn, KA; Chariton, AA; Penrose, B; Langendam, AD
    There are a range of potential options for the decommissioning of offshore petroleum infrastructure, including: complete removal; removal of topside infrastructure with subsea infrastructure left in situ; or partial removal or modification of infrastructure. The current decommissioning liability in Australia is estimated to exceed US$40 billion over the next 50 years. This is founded on the base-case regulatory position of complete removal of all infrastructure, with over half the liability occurring in the next 10 years. In Australia, a recently updated decommissioning framework requires that the planning for decommissioning begins from the outset of the project, and plans are matured throughout the life of operations. Successful decommissioning of subsea oil and gas infrastructure requires an effective and safe approach for assessing and managing chemical and radiological residues. Naturally occurring radioactive materials (NORM) are ubiquitous in oil and gas reservoirs around the world and may form contamination products including scales and sludges in topside and subsea infrastructure. In situ decommissioning of infrastructure left in the marine environment has many ecological benefits including establishment of artificial reefs, economic benefits from associated fisheries, reduced costs and improved human safety outcomes. However, there may be ecological risks associated with leaving infrastructures in the marine environment that are not well understood. Following a scenario of in situ decommissioning of subsea petroleum infrastructure, marine organisms occupying the exteriors or interiors of production pipelines may have close contact with the scale (metal and radionuclide contaminants). Consequently, radio- and chemo-toxicological effects from the scale could occur respectively. This paper considers the current assessment process for NORM-contamination products in oil and gas systems, recent and emerging Australian research in marine radioecology. Here we demonstrate a tiered approach to assess the ecological impacts of pipeline scale related to decommissioning practices, and identifies key research priorities. This can further aid our understanding of the fate of NORM contaminates in subsea oil and gas systems and guide Australia-specific (expand to other petroleum operating countries) risk assessments for infrastructure decommissioning options. The creation of a tiered assessment will enable industry to optimise decommissioning solutions and allow regulators to set clearer expectations on the requirements for environmental protection.