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- Volume 18, Issue 2, 2000
First Break - Volume 18, Issue 2, 2000
Volume 18, Issue 2, 2000
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A Geoscientist's life
By K.J. WeberKoen Weber, professor in production geology at the Technical University, Delft, retired at the end of last year. To mark the occasion and honour his career both as an academic since 1984 and previously as a distinguished research engineer with Shell, a symposium on production geology was held in Delft. The seminar included contributions from a number of present and past colleagues and former students. We publish here Professor Weber's own farewell address entitled 'Adventures in Soft Science', one man's view of where the geosciences have reached at the beginning of the new millennium enriched by the experiences of a lifetime.
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Statfjord study demonstrates use of neural network to predict porosity and water saturation from time-lapse seismic
Authors T. Oldenziel, P. de Groot and L. B. KvammeWith an estimated STOIIP of more than 1 billion m3, Statfjord is the largest oil discovery in the North Sea to date. Structurally the field is a tilted fault block with Jurassic beds dipping westward at 6 to 8° and truncated on the faulted and eroded East flank (Kirk, 1980 and Fig. 1). The field is divided into three main reservoir units, which are in order of decreasing importance: Brent, Statfjord and Dunlin. Since its discovery in 1974 almost 200 wells have been drilled. The cumulative production from the start of production in 1979 until the end of 1997 was 550 million m3. This represents approx. 55% of the initial oil in place and 83% of the official recoverable reserves of 662 million m3. All reservoirs have been partly drained so far during the field's history. In the early years, produced gas was reinjected into the Statfjord reservoir at an up dip position, while the Brent reservoir was depleted until pressure maintenance by down flank water injection was established in 1986. This resulted in extensive gas and water breakthroughs in the production lines and a change in drainage strategy. In the last decade the strategy has been based on in-fill drilling to produce by-passed oil and remaining oil in structural traps and recently in combination with gas and water injection to mobilize remaining oil. To find unswept or by-passed oil three consecutive 3D seismic surveys, acquired in 1979, 1991 and 1997 respectively, have been the basis for seismic monitoring analysis. In this case study, only the latter two surveys were used. The aim of the study was to predict porosity and water saturation at the respective acquisition dates. For each survey five seismic volumes were available: mid- and far-angle reflectivity, mid- and far-angle elastic impedance, and acoustic impedance. The partial stacked cubes have similar fold and contain angles around 15 and 25°, respectively. The inversion method used was a global search through a simulated annealing scheme using a constant wavelet. Some 130 wells were used, each with an extensive suite of measured logs and 1991 and 1997 timeequivalent logs. The reservoir simulator and a modified Gassmann fluid replacement algorithm were used to compute the time-equivalent logs. For most wells a neural network predicted a measured shear sonic log from measured sonic, density and gamma ray logs.
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Comparison between single and multi-channel cable telemetry systems in harsh terrains
By P. BurgerThis short paper begins with a brief history of the milestones in seismic instrumentation. The advantages and disadvantages of single channel vs. multichannel telemetry system architecture are shown, not only in terms of seismic quality but also in terms of capital expenditure and operating flexibility. An example of a heliborne crew, using single and multichannel untis in the same prospect, confirms that all these parameters must be taken into consideration when selecting which telemetry system to use.
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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)