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- Volume 19, Issue 12, 2001
First Break - Volume 19, Issue 12, 2001
Volume 19, Issue 12, 2001
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Marine seismic acquisition surveys and technology
Authors A. McBarnet, S. Hegna, J.W. Schoolmeesters and N.C. QuinnCollected articles about Marine seismic acquisition surveys and technology. -'Why WesternGeco believes Q-Marine is taking seismic to a new level', by Andrew McBarnet -'Sampling considerations related to modern towed streamer acquisition geometries', by Stian Hegna and Jan W. Schoolmeesters -'New steps in the remote QC monitoring of positioning data in marine seismic', by Nicola C. Quinn
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Time to reassess the Odell factor in oil and gas
By A. McBarnetFor 40 years now, Peter Odell, Professor Emeritus of international energy studies, Erasmus University, Rotterdam has been challenging the conventional wisdom on the politics and economics of the international oil and gas industry. For much of that time he has been a lone critic fighting to be heard. The publication of a collection of his writings since 1961 offer an opportunity to assess the validity of what he has had to say. Andrew McBarnet spoke to Prof. Odell about his controversial work and life on the outside, and provides some historical perspective on the issues of the day.
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Mapping reservoir pressure and saturation changes using seismic methods - possibilities and limitations
Authors M. Landrø, P. Digranes and L. K. StrønenIn this paper, travel-time and amplitude information from time-lapse seismic data are combined to improve the mapping of an over-pressured reservoir segment. The increased pore pressure is caused by water injection into the segment. According to RFT measurements in the well, the pore pressure increase is of the order of 50-80 bars. The observed amplitude increase (between the base line and the monitor survey) associated with the top reservoir event is of the order of 100-200%. A rough estimate of the velocity changes needed (assuming that the density change is negligible) to explain this amplitude change is a 20% reduction in the P-wave velocity. The observed pull-down effect (time-lapse travel-time shift) measured over the whole reservoir thickness is of the order of only 4-6 ms, indicating a gradual change in velocity below the top reservoir event, decreasing with depth. Interpretation of time-lapse seismic data depends on knowledge of the relationship between the seismic parameters and the typical reservoir parameters we want to map, such as, for instance, pore pressure changes and fluid saturation changes. The established link for bridging the gap between the two types of parameter is rock physics. For saturation effects, the Gassmann equations form a reasonable working basis, enabling us to make quantitative estimates of how much each of the seismic parameters changes with, for instance, water saturation. However, for pore pressure changes, the theoretical basis is weaker, and we have to rely on ultrasonic core measurements in order to establish a link between pore pressure changes and the corresponding changes in seismic parameters. One major weakness of the core measurements is that the core sample is damaged during the coring process (Nes et al. 2000). Artificial cracks are probably formed during the anisotropic stress unloading process. Even if the core sample is reloaded to simulate in situ stress conditions for the ultrasonic core measurements, it is not very likely that the original crack state of the sample is re-established. Furthermore, we have to deal with the upscaling problem for our core measurements: Are the ultrasonic measurements made on the small core sample representative at a seismic scale?
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Monitoring water flow in the unsaturated zone using georadar
Authors I. Trinks, H. Stümpel and D. WachsmuthTime-lapse measurements of fluid movements in the subsurface have become increasingly important, not only in the exploration of hydrocarbon reservoirs but also in environmental geophysics. Groundwater contamination from industrial ruins, leaking pipes, rubbish pits without base sealing and the excessive use of fertilizers in agriculture are all reasons for finding a suitable method for detecting fluid flow in the subsoil. To be able to recognize and remove the cause of groundwater contamination it is necessary to trace the path taken by the contamination and to locate its source. Pollutants normally reach the groundwater as drain water. Rainwater seeping into the subsurface does not penetrate as a uniform front but often follows preferential flow paths in the form of so-called ëfingersí (Baker & Hillel 1990; Liu et al. 1994a; Babel et al. 1995).
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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)