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- Volume 20, Issue 2, 2002
First Break - Volume 20, Issue 2, 2002
Volume 20, Issue 2, 2002
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How a comprehensive approach to a 3D transition zone survey paid off in the Malacca Strait, Indonesia
In this brief extract from a longer paper Canadian company Geo-X Systems reports on a transition zone project carried out by contractor Grant Geophysical in Indonesia for Kondur Petroleum which required an innovative use of its ARAM-24 seismic recording system. Geo-X says that the equipment described in the article has been further developed and improved in the new ARAM ARIES telemetry recording system, designed with the emphasis on flexibility to work in diverse environments.
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Blackfoot 3C/3D test makes the point for VectorSeis
Authors J. Tessman and B. GoodwayInput/Output has been promoting its three-component VectorSeis sensor for land seismic surveys over the last two or three years. Here Jon Tessman of Input/Output and Bill Goodway of PanCanadian Energy Corp describe the key field test carried out in Canada on the way to commercialization. The Blackfoot field represents a style of stratigraphic trap common in the Western Canadian Basin. In many cases the acoustic impedance of the regional formations is similar enough to the reservoir to make detection through conventional P-wave seismic difficult at best. Observations based on log and core analysis suggested that the application of Vp/Vs techniques could provide a seismic method for identifying channel location and evaluating reservoir quality. These considerations led to the Consortium for Research in Elastic Wave Exploration Seismology (CREWES) acquiring a 3C/3D survey over the Blackfoot field in 1995. In 1999, PanCanadian volunteered the site for the first precommercial test of the VectorSeis sensor, a three-component, MEMS based, digital accelerometer fabricated using bulk micromachining of commercial 6 in silicon wafers (for more details on the manufacturing, see references). A Mega- Bin 3D survey was carried out over a large portion of the legacy CREWES survey. While four years of hydrocarbon production, acquisition, processing, and sensor differences prevented quantitative analysis of VectorSeis performance, this paper evaluates several qualitative aspects. Processing of the compressional and converted wave datasets showed the VectorSeis data to be comparable with the legacy geophone data. Further amplitude and Vp/Vs analysis confirmed these conclusions as well as the viability of Vp/Vs techniques as a tool for the identification and evaluation of compound incised valley fill systems in western Canada.
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From seismic to simulator through geostatistical modelling and inversion: Makarem gas accumulation, Sultanate of Oman
More LessG. Shanor, M. Rawanchaikul & M. Sams from Jason Geosystems Middle East and R. Muggli, G. Tiley & J. Ghulam from Petroleum Development Oman discuss how reservoir characterization results achieved with an integrated team effort led to a significant increase in reserves of the Makarem Field, Sultanate of Oman. This paper presents an applied workflow and the results of an integrated team effort to define the commercially recoverable reserves associated with the Buah fractured carbonate reservoir of the Makarem sour-gas accumulation in the Sultanate of Oman. The status at the start of the study was that three wells had been drilled into the field, a discovery well Makarem-1 and two exploratory-appraisal wells Makarem-2/-3. Tests of Makarem-1/-3 showed good flow rates, but the Makarem-2 test indicated very tight formation with no flow. The estimated Gas-Initially In-Place (GIIP) volumes based on the assumption of mainly fracture porosity were insufficient to justify field development. The main goal of the study was to determine the potential for significant matrix flow which would be critical to the commerciality of the field. In this paper we focus on the method applied to develop multiple 3D static model realizations from the available, seismic, well log, geological and engineering information and the use of these models in the assessment of development scenarios. With multiple models available, uncertainty of reservoir parameters determined from static models may be quantified. Further, the P50 model (in terms of volumetrics) was taken into a flow simulator for dynamic modelling to evaluate the potential for matrix flow. The modelling study confirmed a high likelihood of a sufficient matrix porosity contribution to flow. As a result, Makarem-3 was re-tested specifically to address the fracture/matrix flow transition. The test was successful and proved a significant contribution of the matrix to flow, providing support for the reliability of the models. The reserves proved-up by this exercise form part of the long-term development planning for gas supply in the Sultanate.
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SeisMovie aims to be a blockbuster for 4D seismic reservoir monitoring
A continuous seismic monitoring system developed by CGG, Gaz de France (GdF) and Institut Français du Pétrole (IFP), is now being deployed at the Gaz de France reservoir in Saint-Clair-sur-Epte, north west of Paris, after a successful four-year testing period on site at Céré-la-Ronde, France. Based on a permanent network of seismic sources and vertical buried receiver antennae, SeisMovie is used to log subtle variations which might go undetected using conventional 4D techniques. In this article CGG describes the technology and how the absence of a seismic crew means data are collected with minimum environmental impact.
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The Corinth Rift Laboratory: monitoring of active faults
Authors I. Moretti, J.P. Delhomme, F. Cornet, P. Bernard, C. Schmidt-Hattenberger and G. BormIn their aim to understand the hydraulic behaviour of faults and fractures, and their changes with stress variation, geoscientists are still poorly armed. On the one hand, data indicate that the rheology of faulted strata plays a major role: shale may create clay smearing (Lehner & Pilaar 1997), whereas, at temperatures over 80/100 °C, pressure solution processes quickly seal fractures in sandstones after rupture (Moretti et al. 2000; Labaume & Moretti 2001). The hydraulic behaviour of discontinuities also appears to be stress-dependent (Sibson 1994), and may therefore change during the depletion of oil and gas fields. We are still unable to quantify these changes and indicate eventual thresholds. On the other hand, fluid pressure influences the friction on the fault planes, and therefore changes the rate of displacement. A large number of seismologists consider that the low average friction coefficient in large fault zones is due to high fluid pressure (Evans 1992 and many others). The permanent and instantaneous hydraulic behaviour of faults and fractures under a stress/strain regime obviously differs due to diagenetic processes, but the rate of the fluid/rock interactions which could be related to the build up of high pressures in the faults themselves is still a subject of debate. In order to clarify these issues, a complete dataset is necessary. European academic and private laboratories (as well as some oil companies) have decided to pool their efforts to collect such a dataset by creating the Corinth Rift Laboratory (CRL), with the help of the EC. The goal is to investigate fault mechanics and their relation to fluid flow and earthquakes by continuous monitoring of strain, seismicity, fluid pressure and geochemistry – at the surface and at various depths in boreholes intersecting active faults. Due to the huge volume of data collected and the necessity of distributing these data to various centres, research in data management is also being carried out. Around the world, two other ambitious projects have been set up with the same goals but in different geological contexts: one to monitor the San Andreas fault, which is a strike-slip fault outcropping in granite, and a second to drill the subduction zone in Japan. In our case, we will drill extensional faults through sedimentary rocks; mainly limestones.
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Use of V0-K depth conversion from shelf to deep-water: how deep is that brightspot?
More LessAs worldwide hydrocarbon exploration moves into progressively deeper waters, there is a growing requirement for the depth conversion of seismic times in areas with little velocity control. The V0-K method is a familiar way of depth converting seismic reflection travel times. While this method can give excellent results, large errors may be produced when it is used for regional surfaces with large relief, for instance when using velocity data from wells on the continental shelf to make prognoses for adjacent deep water areas. This paper uses exploration wells in the UK West of Shetlands area, which span water depths from 100 to 1000 m, to constrain and test the accuracy of different V0-K based depth conversion approaches for the Cenozoic post-rift section of deep water areas. The average velocity method, which implies vertical iso-velocity contours, and the traditional form of the V0-K method, which implies horizontal iso-velocity contours, are used as benchmarks to display the advantages of using the seabed as a datum and of allowing lateral variation in the V0 and K parameters. The seabed datum reduces nonuniqueness in the V0 parameter, particularly in deep water. The best depth conversion results in this study are obtained by determining relationships between both V0 and K and the water depth, although good results can also be achieved with optimized single V0 and K values and a seabed datum.
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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)