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- Volume 5, Issue 7, 1987
First Break - Volume 5, Issue 7, 1987
Volume 5, Issue 7, 1987
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VSP migration by single shot record inversion
Authors J.A. Harwijanto, C.P.A. Wapenaar and A.J. BerkhoutVertical seismic profile (VSP) data have been used for many years to obtain lithological information from the subsurface in the direct vicinity of the borehole, and to 'calibrate' the seismic processing of surface data (Hardage 1983; Balch & Lee 1984). A relatively unexplored aspect of VSP data is the potential to obtain structural information from the subsurface around the borehole. Structural information can be obtained both from surface data and from VSP data by seismic migration. As opposed to surface data migration, however, very few publications on VSP data migration have appeared in the seismic literature. Amongst others, we mention Gazdag & Sguazzero (1983) and Chang & McMechan (1986). Some important complications to be dealt with in VSP migration are the severe variations of the propagation velocity along the borehole, the steep propagation angles (relative to the normal to the borehole) and the sometimes significant deviations of the borehole from the vertical. In this paper we discuss an efficient, wave-equation-based VSP migration scheme which copes with all these problems. The scheme is a generalisation of pre-stack migration by single shot record inversion as proposed by Berkhout (1984).
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Airborne magnetometer and spectrometer survey over Gabon
By D. GuillemotAn airborne magnetometer and spectrometer survey was carried out by CGG over Gabon for the Gabonese 'Ministère des Mines et du Petrole' from April 1983 to February 1984. A total of 243436 line-km were flown over the Precambrian basement for geological mapping and direct uranium prospecting purposes. Due to the variabIe topographic relief, nine blocks were defined. Three blocks were flown with helicopters and six blocks were flown with fixed-wing aircraft. The navigation was performed using SAR imagery and electronic navigation systems (Sperry C1l2 electronic compass, TANS computer, Doppler system).
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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)