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- Volume 37, Issue 8, 2019
First Break - Volume 37, Issue 8, 2019
Volume 37, Issue 8, 2019
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Groningen explosion database
More LessAbstractIn the Netherlands a seismic network is in place to monitor both induced and natural seismicity. Most natural seismicity occurs in the south, over an extensional tectonic regime that can be seen as an extension of the Rhine Graben. Most induced seismic activity occurs in the north of the country and is primarily related to gas extraction and reactivation of existing faults at reservoir level (Spetzler and Dost, 2017; Willacy et al., 2019). In Groningen, in the north east of the Netherlands, an especially dense network is in place. The network is operated by the Royal Netherlands Meteorological Institute (KNMI). Both event data and continuous recordings are publicly available (KNMI, 1993). In the Nineties, a seismic network has been installed to monitor seismicity from the Groningen field and a string of surrounding gas fields (Dost et al., 2017). Since 2014 this network has been expanded with a dedicated network to monitor seismicity from the Groningen field (the G-network, Figure 1), and two gas storage plants (the N- and GK- networks, Figure 1). The area has soft soil and high seismic noise conditions. As a remedy, most of the seismic sensors have been installed in boreholes - in a set-up shown on Figure 1(c). This set-up yields a seismic power reduction up till about 30 dB in the relevant bandwidth (Ruigrok and Dost, 2019).
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Can high-resolution reprocessed data replace the traditional 2D high-resolution seismic data acquired for site surveys?
Authors Julien Oukili, Jean-Paul Gruffeille, Christian Otterbein and Benjamin LoidlAbstractAfter a prospect has been evaluated and the decision is made to drill, the well planning and design phase can begin. We must define not only the best location to enter the target reservoir, but also choose the right surface location to place the drilling rig and the wellhead, without forgetting the well trajectory between the wellhead and the reservoir entry point.
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Towards drone-borne gammaray mapping of soils
Authors Han Limburg, Steven van der Veeke and Ronald KoomansAbstractThere is a strong growth of interest in UAV’s (Unmanned Aerial Vehicles, aka drones) as a sensor platform in geophysical surveying. Not so much to replace traditional piloted airborne surveying platforms (Figure 1). The usefulness of drones as a platform seems much more to replace walking or driving surveys. Drones are very handy tools to survey areas that cannot easily be accessed by foot or by vehicle, and that are too small to be mapped economically with traditional airborne systems.
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First results of geophysical and geotechnical investigations along the Hedwige- and Prosperpolder dykes
Authors Serkan Nuri Elgün, Griet De Backer, Jasper Bink, Wouter Zomer and Patrik PeetersAbstractThe Hedwige- and Prosperpolders are situated on the border of Belgium and the Netherlands near Antwerp, as presented in Figure 1. A polder is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dykes. It is decided that the two polders will be turned into an area with intertidal nature (managed realignment). Together with the ‘Drowned Land of Saeftinghe’ they will be part of the largest intertidal nature area in Western Europe. The reconstruction means that the current dyke along the river Scheldt will become obsolete and partially removed. This presents a unique opportunity to perform full-scale tests on this dyke, which has been in service for several decades. BZ Engineers & Managers commissioned by The Dutch Foundation for Applied Water Research (STOWA) and the Belgian Flanders Hydraulics Research (FHR, Department of Mobility and Public Works) have joined forces to organize these experiments. Together with several other partners, including knowledge institutes, universities and flood managers, the test and experiments will improve understanding of the impact of floods incidents and of climate change. Field experiments on the Scheldt dykes form the core of the collaboration.
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LEGACY DATA
AbstractWhat is the value of ‘old’ data collected decades ago when more sophisticated data are acquired today using modern equipment?
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Smart Exploration: from legacy data to state-of-the-art data acquisition and imaging
Authors A. Malehmir, G. Donoso, M. Markovic, G. Maries, L. Dynesius, B. Brodic, N. Pecheco, P. Marsden, E. Bäckström, M. Penney and Vitor AraujoAbstractDuring the last decade, and possibly in years to come, mineral exploration geophysics has strongly pushed itself towards developing new instruments and hardware solutions capable of addressing the ever challenging near-mine and brownfield exploration issues. New data will be acquired but higher noise levels and restricted access due to mining activities and infrastructure increase the challenge of acquiring data of sufficient quality to answer key geologic questions and define additional resources. Companies that value their existing data and reassess them rigorously and continuously are likely to benefit.
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3D seismic datasets applied to mineral exploration: revisiting three Canadian case studies
Authors Gilles Bellefleur and Erick AdamAbstractThe benefits of working with legacy seismic data are broad and valued in a wide range of geoscience applications and result from the comprehensive volume of industry and public seismic data acquired over several decades. Legacy seismic data exist in many parts of the world including areas that, due to stricter regulatory processes, environmental restrictions, demographic changes, or other factors would be challenging or even impossible to survey today. Examples are numerous but one includes 2D marine seismic data acquired in the 1980s with a large airgun array to provide a deep cross-section through the Appalachians beneath the now sensitive Gulf of St Lawrence, eastern Canada (Marillier et al., 1989). Sometimes benefits arise through the use of newly developed techniques to extract additional information from legacy seismic data. This idea is obviously not new and many examples can be found in the literature. One example is the use of extended Vibroseis correlation developed in 1980s (Okaya and Jarchow, 1989) applied to increase the depth range of marine Vibroseis seismic data acquired in 1971 in two of the Great Lakes of North America (Milkereit et al., 1992). Marine seismic data in the Great Lakes are sparse, but contain information about deep Grenvillian terranes that, in this case, could only be revealed using a technology developed more than a decade after data acquisition.
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On the use of legacy AEM data
Authors Viezzoli Andrea, Menghini Antonio and Vlad KaminskiAbstractThe term ‘legacy data’ is rather loose. It always means ‘old data’, but there is no consensus on what is ‘old’, especially across disciplines/data types. In this paper we focus on Time domain AEM data post 2000. By then, virtually all systems were equipped with a Digital Aquisition System (DAS). It is also around those years that Time Domain (TD) systems started to gain ground on Frequency Domain (FD) systems, thanks to the introduction of concentric helicopter borne systems. However, it is time domain systems that can most benefit from renewed analysis modelling. Time domain data can take longer to model, which is one of the reasons they were often never properly inverted at the time. On the other hand, they often span larger frequency ranges (3–4 decades instead of 2–3 of the FD) while also displaying clearer signatures of ‘new’ physical processes such as Airborne IP (AIP) and superparamagnetic effects (SPM). Finally, most development in new generation of AEM systems takes place in TD, which fosters continued R/D.
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Giving the legacy seismic data the attention they deserve
Authors Musa Manzi, Alireza Malehmir and Raymond DurrheimAbstractKey minerals may soon be in short supply as shallow mineral deposits are mined-out; therefore exploration for economically feasible deep-seated deposits to sustain a long-term global growth is a great challenge. New deposits are likely to be found using reflection seismic surveys in combination with drilling, field geological mapping and other geophysical methods. Seismic methods have already have contributed significantly to the discovery of some of the world’s major mineral deposits (Milkereit et al., 1996; Pretorius et al., 2000; Trickett et al., 2004; Malehmir and Bellefleur, 2009; Malehmir et al., 2012). However, use of the method is not widespread because it is deemed to be expensive. Although improvements in computing capabilities have led to cost reductions, the costs are still beyond exploration budgets of many companies. Thus, mining companies have had little financial ability to acquire new reflection seismic data, and very little governmental support has been available to acquire research seismic surveys for mineral exploration.
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The role of land gravity data in the Neves-Corvo mine discovery and its use in present-day exploration and new target generation
AbstractSeveral blind massive sulphide deposits associated with the Iberian Pyrite Belt (IPB) Volcano-Sedimentary Complex (VSC) (Figure 1) were discovered in SW Iberia using joint interpretation of geological and geophysical models, such as Neves-Corvo (Albouy et al., 1981; Leca et al., 1983) and Lagoa Salgada (Oliveira et al., 1998) in Portugal, and Valverde and Las Cruces in Spain. In the IPB Portuguese sector, the former government agencies Serviço de Fomento Mineiro (SFM) and Instituto Geológico e Mineiro (IGM), as well as LNEG, fostered the acquisition of systematic geophysical surveys, in particular gravimetry, in the region during the second half of the 20th century.
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Reprocessing aeromagnetic data using modern semi-automatic interpretation methods
More LessAbstractModern airborne geophysical data acquisition systems (such as aircraft, helicopters, and drones) can aquire large amounts of data quickly. Semi-automatic intepretation methods that provide initial estimates of source location and depth have been in widespread use since the 1970s. The output of these methods is used as the starting point for a detailed interpretation, based on forward modelling and inversion. One of the earliest methods in widespread use on computers was Euler deconvolution (Thomson, 1982; Reid et al., 1990)
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Volumes & issues
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Volume 42 (2024)
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Volume 41 (2023)
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Volume 40 (2022)
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Volume 39 (2021)
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Volume 38 (2020)
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Volume 37 (2019)
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Volume 36 (2018)
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Volume 35 (2017)
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Volume 34 (2016)
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Volume 33 (2015)
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Volume 32 (2014)
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Volume 31 (2013)
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Volume 30 (2012)
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Volume 29 (2011)
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Volume 28 (2010)
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Volume 27 (2009)
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Volume 26 (2008)
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Volume 25 (2007)
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Volume 24 (2006)
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Volume 23 (2005)
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Volume 22 (2004)
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Volume 21 (2003)
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Volume 20 (2002)
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Volume 19 (2001)
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Volume 18 (2000)
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Volume 17 (1999)
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Volume 16 (1998)
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Volume 15 (1997)
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Volume 14 (1996)
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Volume 13 (1995)
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Volume 12 (1994)
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Volume 11 (1993)
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Volume 10 (1992)
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Volume 9 (1991)
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Volume 8 (1990)
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Volume 7 (1989)
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Volume 6 (1988)
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Volume 5 (1987)
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Volume 4 (1986)
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Volume 3 (1985)
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Volume 2 (1984)
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Volume 1 (1983)