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- Volume 36, Issue 3, 2018
First Break - Volume 36, Issue 3, 2018
Volume 36, Issue 3, 2018
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Depth calibration of fibre-optic distributed vibration sensing measurements
Authors T. Dean, T. Cuny, A. Constantinou, P. Dickenson and E. HamoucheAbstractDepth calibration for conventional vertical seismic profile (VSP) tools is relatively straightforward, typically being achieved by correlating gamma-ray logs. For fibre-optic distributed vibration sensing (DVS/DAS) measurements, however, calibration is more problematic because the location of positions along the fibre cannot be readily correlated to wellbore depth. Here we describe five methods for depth calibrating DVS data. The end-of-fibre and freeze methods can be applied to permanent and temporary fibre installations whereas the downhole-source, hammering-on-the-wellhead, and symmetry-detection methods are primarily applicable to permanent installations. Methods based on the raw backscatter measurements are more likely to be accurate because they do not involve any effects from the processing stages required to extract the phase. The freeze and downhole-source methods both suffer from problems associated with picking an amplitude peak that has been smoothed by the gauge length. If a permanently installed fibre must be depth calibrated at a variety of depths, downhole-source is the most promising method. The symmetry-detection technique is straightforward and robust but relies on the fibre following the same path into and out of the well. The error associated with the hammering technique is significantly larger than the other techniques and we do not recommend its use.
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The Niobrara formation in the Southern Powder river basin, Wyoming: An emerging giant continuous petroleum accumulation
More LessAbstractThe Niobrara Total Petroleum System (TPS) covers an extensive area across the Rocky Mountain Region, US. In the Powder River Basin (PRB), the petroleum system consists of source beds in the Upper Cretaceous Niobrara Formation as well as reservoirs in the Upper Cretaceous Frontier, Turner, Niobrara, Sussex, Shannon, Parkman, Teapot, and Teckla. The Niobrara is a deep-water hemipelagic carbonate mudrock and is Coniacian to early Campanian in age and approximately 150–650 ft thick. The formation, where productive, has low porosity (< 10%), low permeability (<0.01 md), and pore throat sizes less than 0.1 micron. The immature-mature present-day depth boundary is approximately 8000 ft. The formation is subdivided informally into three units in the PRB (A, B, and C). The units consist of cycles of marls and chalks.
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Offshore Argentina: Lessons from previous exploration
Authors Jonathan Castell, Andrew Lavender and James ScotchmanAbstractArgentina’s Energy and Mining Ministry is in advanced preparations to stage a new offshore licensing round in 2018 — the first in almost a decade. Despite its size (approximately 1.5 million km2, equivalent in scale to the US Gulf of Mexico) and its moderate water depths, there have only been approximately 150 exploration wells drilled to date, making it one of the least explored Atlantic provinces.
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Shallow water Gabon 3D: focused processing images pre- and post-salt prospectivity
Authors Paolo Esestime, Howard Nicholls, Karyna Rodgriguez, Neil Hodgson and Laura ArtiAbstractIn 2017 Spectrum conducted a major 3D seismic acquisition programme of approximately 11,500 km2 in shallow water offshore South Gabon (Figure 1). The project was carried out in close collaboration with the Gabonese Authorities (Direction Generale des Hydrocarbures; DGH) and was driven by renewed interest in a proven hydrocarbon province. Continuing exploration since the 1960s has proven all the key elements: source rock presence and maturity, reservoir presence and effectiveness, seal and oil charge into structural and combined structural-stratigraphic traps. Indeed, many oil fields, such as the Olowi Field, have been discovered and are producing in the onshore and nearshore.
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An opportunity to re-evaluate the petroleum potential of the Douala/Kribi-Campo Basin, Cameroon
AbstractThe recently announced Cameroon licence round running until 29 June 2018 provides oil companies with a significant opportunity to acquire large swathes of acreage in the Douala/Kribi-Campo (DKC) and Rio Del Rey (RDR) Basins. The DKC Basin is divided into two sub-basins, the Douala Sub-basin in the north and the Kribi-Campo Sub-basin in the south. The RDR basin, situated at the toe of the Niger Delta (Figure 1), is a mature basin with significant infrastructure and production. In contrast, the DKC Basin, which is the focus of this paper, is relatively underexplored, yet there are marked grounds for optimism in its petroleum potential. The DKC Basin is separated from the RDR Basin by the Cameroon Volcanic Line (Figure 1) and is the northernmost basin formed during rifting and separation of the South Atlantic conjugate margins, a province harbouring prolific hydrocarbon accumulations.
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Derisking the Thebe Discovery through cognitive interpretation
More LessAbstractThe Exmouth Plateau, offshore Northwest Australia has been an area for hydrocarbon exploration for several decades, with a number of significant gas and oil fields being discovered. One of these encounters is the Thebe Discovery. With the successful drilling of the Thebe-1 well in 2007, which penetrated a 73 m gas column, further well activity continued. The Thebe-2 appraisal well was drilled roughly 20 km NNE of the original discovery well in 2008 and again encountered a significant gas column, which led to a total field estimate of 2–3Tcf gas in place. The gas accumulation encountered in both of these wells is clearly visible on seismic reflectivity data and can be traced across the crest of a rotated fault block. So, if the hydrocarbon field has been clearly identified and delineated, why is the discovery not in development yet? In this study, the petroleum system of the Thebe Discovery will be investigated using Cognitive Interpretation techniques.
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West of Shetland broadband 3D seismic: Extending the exploration life of Europe using new seismic technology
More LessAbstractThe West of Shetlands exploration area lies between the Faroe Islands and the Shetland Islands in the north-east Atlantic (Figure 1).
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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)