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- Volume 21, Issue 9, 2003
First Break - Volume 21, Issue 9, 2003
Volume 21, Issue 9, 2003
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Comparing Cesium and Potassium magnetometers
Authors R. Johnson and K. SmithGeometrics staff of engineers and physicists have reviewed the article Development of a high sensitivity potassium magnetometer for near surface geophysical mapping published in the May issue of First Break. We have found the article contains inaccuracies and some theoretical misstatements that we feel should be addressed. To that end we offer the following comments: 1. Equation (4) (on page 83) is incorrect in that the author has ignored the effect of bandwidth on system performance. It is not the total noise that is of concern but the noise density (typically in nanovolts per root Hz) that is at issue. Components in the noise that are far from the Larmor frequency are easily filtered out in the electronics. However, there is no way to effectively remove noise that is very near the Larmor frequency. This is why, in spite of its much narrower line width, the performance of the Potassium is not better than that of a Cesium magnetometer. We can verify this through direct comparison of published specifi- cations. 2. The Cesium magnetometer is capable of 0.0004nT/√Hz- RMS. It should be noted that there are several Cesium magnetometer array installations using high performance counting systems wherein low noise data is being collected at 100Hz or 120Hz on up to 7 or 8 sensors simultaneously (Naval Research Labs and Oakridge National Labs MTADS systems). All statements referring to a maximum of 10Hz sample rate and low sensitivity specifications (0.05nT) are in error.
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Prediction and productivity improvements in quantitative interpretation via rock physics modelling and interpreter led automation
Authors M. Millwood Hargrave, J. Haynes and R. SimmMartyn Millwood Hargrave, managing director and Dr Jamie Haynes technical director of IKON Science together with Dr Rob Simm of RPA discuss new developments in quantitative reservoir interpretation using rock physics and seismic modelling to give predictive improvements in 3D and 4D workflow and look at the potential for new automated fault interpretation methods to enhance seismic interpreter’s capabilities.
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History matching using both production and 4D-4C seismic
Authors A.Y. Al-Naamani and C. MacBethAli Al-Naamani and Colin MacBeth, Heriot-Watt University, Edinburgh, UK discuss some refinements to history matching in 4D seismic analysis using PS time-lapse data. The purpose of time-lapse seismic measurement is to be able to monitor the reservoir during production or improved oil recovery by detecting induced changes in the seismic attributes. Within reservoir simulation, the aim is to develop a realistic reservoir model, which agrees with all available static and dynamic information from which we can make accurate future predictions about reservoir performance and plan further developments. Reservoir model history-matches are non-unique, more than one combination of reservoir model input parameters will match observed production. In most cases, we have an incomplete understanding of our reservoirs and how they will behave during production. However, issues such as connectivity, permeability pathways, and water encroachment will lead to large uncertainties. We often do not know how our reservoirs will behave until we flow them. This is why time-lapse seismic should be an integral part of any field development plans. Time-lapse seismic monitoring is a valuable asset to reservoir engineering, because it provides 3D dynamic data rather than the spatially limited well test and production data. Most seismic history matching studies are achieved by constraining the reservoir model with PP time-lapse data. The aim of this work is to judge the value of incorporating PS time-lapse data as an additional constraint in the process of performing a qualitative seismic history matching.
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4D seismic pressure-saturation inversion at Gullfaks field, Norway
Authors D. Lumley, D. Adams, M. Meadows, S. Cole and R. ErgasDavid Lumley, Don Adams, Mark Meadows, Steve Cole and Ray Ergas* of 4th Wave Imaging, a Californian company specializing in advanced 4D seismic software development, describe its application of proprietary pressure-saturation inversion to the Statoil operated Gullfaks field, offshore Norway. Time-lapse 4D seismic reservoir monitoring is experiencing rapid acceptance as a practical reservoir management tool, as evidenced by three full days of technical presentations on the topic at the recent June 2003 EAGE Conference in Stavanger, Norway. The 4D seismic technique is useful to help map bypassed oil, monitor costly injection programs, and improve our understanding of reservoir compartmentalization and the fluidflow properties of faults. Most of the applications to date have tended to be qualitative rather than quantitative. For example, 4D seismic practitioners often examine time-lapse seismic amplitude maps and develop a qualitative interpretation of where they think fluids are flowing in the reservoir, constrained by supporting data such as geologic control, well logs and engineering production information. However, there is a growing desire to obtain more quantitative results from 4D seismic data, for example, the ability to create pressure and saturation maps or volumes with calibrated physical units of saturation and pressure to assist engineering workflows and reservoir management decisions. This paper presents a case study in which we apply quantitative Pressure-Saturation Inversion (PSI) technology developed by 4th Wave Imaging to the 4D seismic project at the Gullfaks field, offshore Norway.
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Placing petroleum systems and plays in their basin history context: a means to assist in the identification new opportunities
By H. DoustThis article describes a proposed means to envisage the development of plays and petroleum systems in the sedimentary cycle or basin stage context in which they occur. The approach can help to visualise the relat ionship between tectostratigraphic basin evolu tion and potential hydrocarbon resources, and thus assist in prospectivity assessment. It could also provide a valuable framework for the use of analogue play data in exploration. Briefly, the methodology comprises the following ; Characteristic sedimentary basin types, for example syn- to post-rift basins, are sub-divided into their natural tectonic cycles and stages. The latter are then plotted against the depos itional environment-defined lithofacies that typify the basin type. In the matrix produced, the domains of petroleum systems present and the 'trajectories' of defined sedimentary basins or parts of basins are plotted, so that analogous area s can be directly compared. Plays developed in known basins and provinces may then be defined and located in their natural basin-evolutionary and petroleum system environment; In principle , this should make it easier to identify truly appropriate analogue plays, drawn from widespread, possibly global distributions. Use of the concept is illustrated by reference to Tertiary basins in Southeast Asia and in the central and northern North Sea provinces.
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Sandstone intrusions: detection and significance for exploration and production
Authors M. Huuse, D. Duranti, C.G. Guargena, P. Prat, K. Holm 1, N. Steinsland 1, B.T. Cronin 1 and N. HurstEarly recognition of sandstone intrusions is a key factor in maximising exploration and production success of the Paleogene deepwater sandstone reservoirs of the northern North Sea. Discordant sandstone intrusions are readily detected in cores, image logs and high quality seismic data by cross-cutting relations with the encasing shales. Many examples of “ratty” sands seen in borehole logs and “artefacts” or “channel margins” seen in seismic data have later proven to be sandstone intrusions, with significant implications for exploration and production. The effects of sand remobilisation and injection include increased connectivity between reservoir compartments, thief sands caused by brecciation and injection into the seal, and large-scale modifications of reservoir geometry, in particular top reservoir. Detailed case studies from the North Sea Paleogene and pilot studies including various other deepwater clastic successions indicate that sandstone intrusions could prove to be an important factor in the development of some highly prolific deepwater provinces such as the West African Atlantic margin. Early recognition of sandstone intrusions in such areas is important for optimal development planning. It requires that the appropriate borehole and seismic data are acquired, and that sandstone intrusions are incorporated in the interpreter’s mindset.
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E-learning for geoscience: an educational approach
Authors G. Toxopeus, E. Slob and M. DraijerIn the summer of 1999, the department of Applied Earth Sciences of Delft University of Technology started a project to stimulate instructors in the use of a web-based learning environment. The idea was that instructors would electronically support their B.Sc. and M.Sc. level educational courses. A small group of enthusiastic instructors was kick-started with an introductory course, and they began to use the virtual learning environment BlackBoard. It was soon discovered that this new environment changed the tutor-student relationship completely, and questions arose on how to use course content in such an environment, and what role it should play in the new communications options. Here we explore some of the problems faced, and we illustrate them with five examples of how the knowledge model can be used, and how the creative thinking of our instructors has enriched our educational program.
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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)