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- Volume 25, Issue 4, 2007
First Break - Volume 25, Issue 4, 2007
Volume 25, Issue 4, 2007
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3D PP/PS prestack depth migration on the Volve field
Authors T. Szydlik, P. Smith, S. Way, L. Aamodt and C. FriedrichOcean-bottom seismic (OBS) methods record both compressional (PP) and converted shear-wave (PS) data. PS data have successfully been used to image through gas-obscured zones (Li et al., 2001) and to image reflectors that are weak on PP data (MacLeod et al., 1999), and can also help constrain rock property estimates (Özdemir et al., 2001). Thus, in principle, the use of PS data can significantly mitigate risk in hydrocarbon exploration and production. Unfortunately, imaging of PS data is not straightforward, due to the asymmetry of the PS raypaths (Figure 1). Accurate compressional and shear wave velocities must be derived, and the three-dimensional variability of these parameters must be comprehended by both the imaging and velocity modelling workflows. Velocity anisotropy must also be handled, if present.
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Dual inversion applied to D multi‑component seismic data onshore Libya
Authors C. Hanitzsch, L. de Vincenzi, W. Heerde, J.M. Michel and D. SemondWintershall-Libya’s onshore concession 97 includes the Nakhla field where oil is produced from the almost 4 km deep Sarir sandstone reservoir. For each new production well in the field, as well as for each appraisal or exploration well in the concession and surrounding areas, the main risk is an absence of Sarir sandstone reservoir. Reservoir sandstones can be partly or fully missing because of intrusions of basalt or deposition of volcanoclastics or presence of shallow basement. Figure 1 illustrates the risks involved, providing a schematic view of a 3 km short line, the worst case line with three dry wells and only one oil well. Looking at well statistics, the overall risk is lower but significant, in the order of 10-30%. Much geophysical and geological effort has been spent over the years to understand the issue and, despite much progress in terms of qualitative understanding (Weihe et al., 2004; Fornaciari et al., 2003), there has only been limited success in terms of quantitative prediction, i.e. what is the risk of encountering a non-reservoir in a new well location?
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PP and PS response from volcanic gas reservoirs
More LessNowadays multi-component seismic has gained more acceptance from the hydrocarbon industry than was the case several years ago. Nevertheless, the anticipated breakthrough into a mainstream technology is still to be realized. One of the bottlenecks is the lack of convincing data examples that demonstrate the full benefit of the technology. This is particularly true for land multi-component seismic. As a step towards filling this gap, we present a case study of using land PP and PS converted-waves for characterizing volcanic gas reservoirs in the Daqing oilfield, Northeast China. The Daqing oilfield is the largest producing oilfield in China and has been in production for more than 40 years. Shallow targets at depth of less than 2 km have largely been exhausted and the current focus is on exploring deep targets buried at depths ranging from 2800 m to 3600 m, which provide a good potential for reserve growth. These deep targets are mostly volcanic gas reservoirs, and often give rise to an incoherent P-wave response. Past multi-componentt seismic experiments reveal some potential to use PS convertedwaves to image these targets, but the results have been limited due to data quality issues. Recent advances in digital MEMS (micro-electro-mechanic-systems) sensors have rekindled interests in using converted-wave data to delineate the volcanic reservoirs in this area. Compared with conventional geophones, the MEMS sensors often have a lower dynamic range and wider bandwidth, giving rise to improved data quality. For this, a multi-component experiment was set up in 2005, and the results are presented in this paper.
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Melding geoscience and information technology to enhance exploration success: a case study from Peru
Authors R. Schrynemeecker, C. Schiefelbein, S. Talukdar, R. Requejo and J. PooleRick Schrynemeecker, Craig Schiefelbein, Suhas Talukdar, Rick Requejo, and Jennifer Poole describe the process involved in providing accessible hydrocarbon prospectivity information for Peru's government oil and gas agency. For the timely evaluation of hydrocarbon exploration opportunities, ready access to supporting data and information is critical. Access to this information via conventional brick-and-mortar data rooms is often problematic and consequently they are increasingly being replaced by web portals that allow remote, secure access to large amounts of specialized data and information. The future need for and value of these solutions will grow as the demand for information in support of hydrocarbon development activities increases. This article describes a solution developed for PERUPETRO, the government agency responsible for promoting hydrocarbon exploration and exploitation opportunities in Peru. A specialized petroleum database was developed and petroleum systems defined as a means to generate renewed interest in hydrocarbon exploration in Peru. The end result allows potential energy investors access to key hydrocarbon exploration information via a Web-enabled portal.
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Using custom‑built GIS tools to facilitate estimation of yet‑to‑find hydrocarbon resources
Authors S. Otto, T. Wilson, M. Lidgett and J. RookeSimon Otto,* Tom Wilson, Mark Lidgett, and James Rooke, Fugro Robertson, explain how detailed spatial databasing of petroleum systems components has been used as a basis for estimating yet-to-find resources for hydrocarbon plays. The bulk of the data that petroleum geoscientists analyze in prospectivity studies have a spatial component, comprising maps of various geological parameters or detailed data located at a specific point location (e.g. down-hole well information). Fugro Robertson (FRL) has been working with GIS solutions for many years, and has built a number of extensions to ESRI’s ArcMap software to assist the workflow of our geoscientists. The methodology for estimating undiscovered hydrocarbon resources (yet-to-find) is based on a detailed spatial examination of the petroleum systems in the study area. The approach used is based on analysis and mapping of the various constituent elements of each play fairway within each basin, based on a sound understanding of the global context of the basin and the factors that create a successful hydrocarbon accumulation. In order to facilitate this workflow, a number of discrete GIS-based solutions have been created to assist the geoscientists, including data management tools, a spatial database of petroleum system components, and tools to assist with detailed data interpretation, statistical analysis and spatial risking.
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Joint MSc programme in applied geophysics: a new concept in geophysics education
Authors A.G. Green, H. Maurer, E. Slob, K. Wapenaar, C. Clauser and R. LittkeAlan G. Green* and Hansruedi Maurer (ETH Zurich), Evert Slob and Kees Wapenaar (TU Delft), and Christoph Clauser and Ralf Littke (RWTH Aachen) introduce a new joint MSc programme in applied geophysics run by three of Europe’s leading education institutions specializing in earth sciences. Readers of First Break are well aware of humanity’s dependence on the Earth’s resources. The principal sources of energy and the vast majority of raw materials required for the construction, manufacturing, and chemical industries are found in the outer layers of our planet. In many areas, vital water supplies are stored in the shallow underground and it is in the upper few tens of metres where household and industrial wastes are commonly buried. Knowledge of the shallow underground is important for the planning of major buildings and civil engineering projects and for predicting the consequences of natural catastrophes.
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Hybrid Gridded Tomography
Authors I.F. Jones, M.J. Sugrue and P.B. HardyHistorically, the practice in velocity model building usually resorted to one of two approaches: the layer-based and the gridded (Jones, 2003). For North Sea type environments where sedimentary interfaces delimit changes in the velocity field and the geology ‘lends itself’ to a layer-based model representation, a layer-based approach to velocity model building has hitherto been commonly used. In other words, we have encouraged preconceived bias, as we consider it to be a meaningful geological constraint on the solution. Conversely, the gridded approach to velocity model building is usually adopted in environments where the velocity regime is decoupled from the sedimentation, and is governed primarily by vertical compaction gradients (velocity increasing with depth), controlled by de-watering, with isovelocity contours sub-paralleling the sea bed.
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Article from the Archive: Some geological advances resulting from North Sea exploration
By K.W. GlennieIn 1964 when the first well was spudded in the search for hydrocarbons beneath the North Sea, little was known about the geology. Since then, in the process of discovering some 35 x 109 barrels (4.8 x l09m3 of recoverable oil and 180 x 1012 ft3 (5 x 1012 m3) of gas, there has been an explosion of geological, geophysical and geochemical data. What seems obvious now but was not realized when exploration began, is that in many areas of the North Sea the stratigraphical sequence is more continuous than in the positive flanking areas of adjacent land. Indeed, those flank areas sourced a great variety of sediments, which were then deposited in a range of basinal environments, all of which makes the North Sea such a fascinating area to study. Furthermore, the area is bisected by a major graben system, the Central and Viking Grabens and the smaller Witch Ground Graben, which has a dominant control on the hydrocarbon distribution. Other grabens further east (Hom, Bamble, Oslo, Gifford) have, as yet, no associated hydrocarbons. But more about that later.
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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)