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- Volume 25, Issue 2, 2007
First Break - Volume 25, Issue 2, 2007
Volume 25, Issue 2, 2007
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A unified 2D land seismic data analysis workflow
By O. YilmazOz Yilmaz, GeoTomo, Houston, describes a time-with-depth workflow for earth modelling and imaging in areas with irregular topography, complex near-surface, and complex subsurface based on analysis of seismic data in shot-receiver coordinates, not in midpoint-offset coordinates. Seismic data acquired in areas with irregular topography, complex near-surface, and complex subsurface require a customized analysis workflow. A near-surface is usually defined as a relatively unconsolidated, low-velocity soil column with less than 30 m thickness. Nevertheless, there are many areas where the near-surface thickness and velocities may vary significantly along the seismic line traverses. Additionally, a near-surface zone may include high-velocity outcrops and layers with vertically varying velocities.
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Time to re-evaluate our approach to 3C land seismic acquisition
By B. HeathBob Heath,* Ascend Geo, argues that the case for MEMS-based 3C land seismic acquisition has been overstated and that other options need to be considered if the ‘full wave’ ideal is to become a commercial reality. Considering the potential advantages which multicomponent exploration can theoretically bring to the land seismic industry, it is amazing that it still accounts for such a small fraction of acquisition recording. Ever since I can remember, 3C has been held up as the holy grail of seismic exploration. Whether we want to look at shear wave arrivals or employ a vectorial view of P-wave noise/signal, it has been about to solve our most complex issues for decades.
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The role of remote sensing data in near-surface seismic characterization
More LessAndreas Laake and Andrew Cutts, WesternGeco, UK show how remote sensing data can enhance seismic-based near-surface model building. The characterization of the near-surface is among the most significant challenges in onshore surface seismic technology. Advanced seismic techniques such as point source and point receiver based methods have revealed the impact the near-surface has on the coupling of sources and receivers and on the generation and propagation of seismic noise modes. Modern seismic data acquisition and processing techniques require corrections for coupling perturbation and surface wave noise to provide correct data for the characterization of hydrocarbon reservoir. Seismic acquisition can only provide local information about the near-surface properties in the vicinity of the sources and the receivers due to the common practice of recording the seismic data along source and receiver lines. The resulting near-surface model is based on spatially limited information.
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Libya’s ambitious goals and the E&P opportunities on offer
By D. MassarasAs we approach the EAGE’s Third North Africa/Mediterranean Petroleum and Geoscience Conference & Exhibition to be held in Tripoli, Libya on 26-28 February 2007, Dimitri Massaras, Africa regional manager, IHS Energy writes about Libya and its ambitious goals for the short and medium term. Libya has emerged after nearly 20 years of trade sanctions as one of the most attractive countries in which to invest exploration funds. As a result, the country has attracted high-levels of interest from around the world as evidenced by the fierce competition for acreage in the most recent bid rounds. Petroleum exploration, production, refining, and marketing of oil and natural gas, as well as LNG production and marketing, are the strongest elements in the Libyan economy and account for about 95% of Libya’s foreign currency earnings and about 70% of government revenues. The upstream and downstream petroleum industry is the key to the national economy of the country and, in 2006, accounted for over $30 billion from exports of crude oil, natural gas, and refined petroleum products.
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Prospects in Libya’s mature and frontier basins
Authors D.P. Le Heron and B. ThusuNew opportunities for hydrocarbon exploration and production in Libya with an emphasis on Palaeozoic prospectivity are reviewed by Daniel Paul Le Heron1 and Bindra Thusu2 in this article, an earlier version of which was published in FIRST magazine3. Libya has been a global favourite for hydrocarbon exploration ever since 1956, when the first wildcat well was drilled. This attraction was primarily a result of the phenomenal success rate of oil discovery in the Sirt Basin (Figure 1) where 19 of the 21 giant fields, with recoverable reserves of 40 billion barrels of oil (bbl), are located. Surprisingly, its ease of exploitation has not diminished the drive for hydrocarbon exploration in neighbouring basins to the west (Ghadames) and southwest (Murzuq) where the search for hydrocarbons continues unabated. It is worth noting that several of the most important, recent discoveries were made between 1979 and 2000, in the absence of an aggressive drilling programme. New play concepts developed during this period have undoubtedly contributed to recent successes, through fruitful collaborations between oil companies and academia.
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Digital analysis brings renaissance for petroleum geology outcrop studies in North Africa
Authors J. Redfern, D. Hodgetts and I. Fabuel-PerezDr Jonathan Redfern,1 Dr Dave Hodgetts,2 and Ivan Fabuel-Perez of the North Africa Research Group, University of Manchester, describe how digital outcrop analysis can provide valuable new geological insights for exploration and production operations in North Africa. The recent increase in hydrocarbon exploration activity across North Africa - in Algeria, Libya, Morocco and Egypt is leading to a renaissance in outcrop studies in the area. The main reservoir, source, and seal facies can all be studied in the field, providing valuable data to better constrain the subsurface geology, reduce exploration risk, help develop new play concepts, and enhance field productivity in North Africa. The North Africa Research Group (NARG) at the University of Manchester, UK, with partners Heriot Watt, Cardiff and Bremen Universities are being supported by 10 leading international oil companies to undertake regional scale outcrop studies. These include regional mapping and correlation to the subsurface, developing a regional sequence stratigraphic framework, regional basin modelling, Apatite Fission Track dating, detailed reservoir characterization, and seismic studies across North Africa.
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Elastic impedance for reservoir fluid discrimination, prospect definition and risk assessment: a North Sea case history
Authors J. Storey, J. Lunchford and J. HaynesBlock 15/18a, operated by Petro-Canada, lies approximately 210 km north-east of Aberdeen (Figure 1) situated in the Outer Moray Firth. Recent technical work has focused on a complex Tertiary channel within which a prominent seismic anomaly exists. This channel system also contains the Macculloch and Brenda fields further to the southeast (Jones et al.) 2004). The channel system exhibits strong seismic reflection character due to significant contrasts in acoustic properties between the reservoirs (Forties and Balmoral sands) and the shale envelope (principally Sele Formation claystones). It is clear from the number of hydrocarbon bearing intervals penetrated by various wells along this Paleocene fairway, both within the channel and on its margins, that the channel system acts as a migration conduit for both oil and gas.
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Articles from the Archive: The determination of the far-field signature of an interacting array of marine seismic sources from near-field measurements – results from the Delft Air Gun Experiment
More LessData from the Delft Air Gun Experiment demonstrate the success of a new method to determine the far-field signature of a marine seismic source array from near-field measurements. The method requires the wavefield of the array to be measured in the near field with hydrophones of known relative sensitivity and in a known geometrical configuration with respect to the monopole source elements within the array. If there are n such source elements, at least n near-field hydrophones are required to determine the wavefield. The results from a North Sea line shot with a tuned airgun array show that the signature deconvolution for the wavelet calculated from these near-field measurements is at least as effective as the signature deconvolution for the measured far-field signature. The same line was shot again with the air guns out of synchronisation by as much as 100 ms; the data from the near-field hydrophones allow a deterministic signature deconvolution to be performed to yield a section very similar to that obtained with the tuned array. Without this signature deconvolution on the detuned data, the recovered section is unacceptable.
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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)