Carbon isotope stratigraphy of the Late Proterozoic Wonoka Formation of the Adelaide Fold Belt: diagenetic assessment and interpretation of isotopic signature and correlations with previously measured isotopic curves

This item is only available electronically.The Wonoka Formation of the Adelaide Fold Belt represents the only well­ described example of a late Proterozoic storm dominated carbonate shelf sequence with the considerable thickness and lateral extent of the formation making it an excellent opportunity for applying the principles of isotope stratigraphy. Sequences exposed at Warraweena, which lies on the boundary between the Central and Northern Flinders Zones, were analysed for stable isotope ratios of carbon and oxygen. Geochemical, petrographic and cathodoluminescent analysis of individual samples was used to identify those carbonates which have experienced significant diagenetic alteration. These values were not included in the interpretation of the formation's isotopic signal. Plotting of the least altered values against stratigraphic height revealed a consistent carbon isotopic trend. This trend was divided into two sections, termed the Lower Wonoka Signal and the Upper Wonoka Signal. The Lower Wonoka Signal is defined by the extremely consistent negative signal (delta13c = -8 to -7o/oo) characteristic of the lower- to mid-Wonoka Formation. This signal is interpreted to be a product of deposition and lithification in basinal waters that contain anomalously light dissolved carbonate. The Upper Wonoka Signal comprises a shift to more positive values (a13c = -5 to +6 o/oo) and is interpreted to be a reflection of carbonate deposition in shallow surface waters, possibly in association with the formation of a partially restricted lagoon. Strontium isotopic analysis reveals 87Sr/86Sr values that are interpreted to be of primary origin. These values, when compared to data obtained by previous authors for the equivalent time period, give an estimated age of 560-590 Ma for the Wonoka Formation.Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 199

Allocation of areas for marine farming in Tasmania

This thesis evaluates the procedures used by the Tasmanian Government to dedicate parts of the marine environment for marine farming purposes, and shows that the process potentially favours the formation of marine farms at the expense of the other users of the marine environment. Furthermore, the Tasmanian Department of Sea Fisheries, which grants marine farming leases and permits and adjudicates over appeals, is also responsible for the promotion and development of marine farming in Tasmania. Due to the rapid expansion of marine farming in the State, it is argued that the Department will be increasingly less able to resist pressure to allocate areas of the sea that are better suited for public rather than private use. The thesis identifies the vesting of parts of the sea as special marine farming areas by the Lands Department in the Department of Sea Fisheries as the point where Crown Land is designated for exclusive private use. A case study of eight marine farming areas in southern Tasmania supports the view that inadequate consideration was given to the public amenity. The thesis argues that the State Government has abrogated its responsibilities, and must develop a mechanism for safeguarding the public interest. The best prospects for a just system rest with the Lands Department before areas are designated for marine farming

The Thin End Of The Test: Operational Procedures For Maximising Successful Formation Pressure Tests While Drilling In Thinly Bedded Sands

Abstract Formation pressure testing while drilling (FPTWD) is an established method of obtaining detailed reservoir pressure data during the drilling process and in operational settings that have very limited formation evaluation alternatives. With many companies, obtaining such data is an integral part of reservoir management strategies, enabling the monitoring of production and injection performance as well assessing reservoir connectivity on a field-wide scale, and in a D frame. FPTWD removes operationally challenging and time-consuming wireline or pipe-conveyed evaluation options that can add unacceptable risk and cost to a project. Obtaining this data as a part of the active drilling phase not only enables a reduction in rig time required for reservoir evaluation, but it also provides an operator valuable information that can impact decisions made on mud weights and casing points while the well is being drilled. FPTWD testing in reservoirs dominated by thin-bedded horizons has traditionally been a hit-and-miss affair, with uncertainties in depth control resulting in a high percentage of tight tests because of pad placement within a shale layer rather than a reservoir horizon. The situation is exacerbated by the automated parameters necessary in a FPTWD tool, whereby tight tests still require the full time interval to complete, but yield no useful pressure information. This paper outlines procedures and techniques successfully applied on turbidite sands in highly deviated wells in deep water fields of Sabah, Malaysia. Utilization of pipe stretch corrections, real-time density images, caliper readings and variations in testing methodology all proved useful in increasing the number of successful tests recorded. By analysing the time required to obtain a valid, three-drawdown test, a reduction of individual test times was made, enabling the decreased overall operational time required. Introduction Turbidite sands make up many of the most important reservoirs of Malaysia. Characterising the thin sand layers can be challenging, because they fall below the resolution of most conventional logs, giving responses that can be highly influenced by surrounding shales (Fig. 1). Various studies were conducted on how to accurately determine key reservoir parameters such as porosity, permeability and resistivity in these layers, including Majid et al (2012), however less work was done on analysing procedures and methodologies utilised with FPTWD tools to determine how to increase the percentage of successful tests in such runs. FPTWD is important for establishing baseline formation pressures in unexploited layers, and determining communication and depletion levels in horizons where production and injection occur. Operationally, determining the pressure of a newly drilled layer is critical to confirm mud weights required to remain over balanced with respect to the reservoir pressure, or conversely, to be sure not to be too over balanced, and therefore avoid fracturing the reservoir. Recording formation pressures in a real-time drilling scenario enables real-time mud weight changes to be made as well as real-time assessments on whether these changes can be made safely (given the pressures of layers already drilled). In some cases, the pressure information will show that an intermediate casing run is required in order to safely drill deeper, making it vital that this data is obtained while drilling. Accurately positioning a test probe, near the bottom of thousands of metres of elastic drill pipe, onto a relatively thin sand layer is extremely challenging, and can lead to tight tests if the probe is positioned on the surrounding shale. Detailed procedures must be developed and followed to maximise the chances of getting a good test in such an environment. These must also be actively updated, through continued analysis of test type and duration, to optimise test times, and therefore, reduce the amount of rig time taken. </jats:sec

Voyages de Gulliver dans des contreés lointaines,

The ill. by Grandville were originally published: Paris : H. Fournier ainé : Furne et cie., libraires-éditeurs, 1838.Engravers include L.H. Brévière, A.A. Piaud, M.U. Sears, P. Verdeil and others.Mode of access: Internet