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- Volume 21, Issue 11, 2003
First Break - Volume 21, Issue 11, 2003
Volume 21, Issue 11, 2003
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How OHM is getting the case for EM sounding methods heard by the E&P offshore industry
By A. McBarnetUK company Offshore Hydrocarbons Mapping (OHM) has encountered a little bit of a problem in its marketing. As Andrew McBarnet reports, it’s because the clients aren’t keen on the company talking about its growing portfolio of successes with a new electromagnetic survey technique
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How airborne gravity surveys can make sense for cost effective exploration
By L. SanderConsensus amongst geophysical professionals is that the overall number of airborne gravity surveys will increase in the coming years. In this article Luis Sander, co-president, Sander Geophysics (SGL), based in Canada, explains with some case histories how the company is deploying its Airborne Inertially Referenced Gravimeter (AIRGrav) system targeted at producing better results than traditional airborne gravity systems.
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Achieving better geology through better geophysics
Authors D. FitzGerald and P. McInerneyAutomated interpretation methods from geophysics that are directly useable in 3D geological models have been a focus of Australian company Intrepid Geophysics in collaboration with its partners around the world. In this article Desmond FitzGerald and Philip McInerney from Intrepid discuss the benefits with reference to gravity and magnetics.
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Improving geologic understanding with gravity and magnetic data: Examples from Gabon, Nigeria and the Gulf of Mexico
Authors J.M. Jacques, M.E. Parsons, A.D. Price and D.M. SchwartzJohn M. Jacques, Marianne E. Parsons, Antony D. Price and David M. Schwartz draw upon recent work to provide evidence as to why gravity and magnetic survey data can still provide vital geological clues for oil and gas exploration. Better understanding of geology on regional and prospect levels using potential field data continues to encourage the melding of these fields to produce enhanced interpretations. Three case studies are presented in this article, all with different geologic settings and targets. All of the examples draw on databases from non-exclusive gravity and magnetic surveys. Two large databases and their interpretation in Gabon and Nigeria were the topics of recent poster papers at the African Symposium, sponsored jointly by the Houston Geophysical Society and the Petroleum Exploration Society of Great Britain (PESGB) in Houston in September, 2003. They are illustrative of the approach that utilizes regional data (in this case satellite-derived gravity) to develop the tectonic framework and more detailed shipborne or airborne gravity and magnetic data to focus on specific targets. The continued high level of activity off West Africa attests to the wide-ranging potential for further development in this region. Many areas, both onshore and offshore, have been extensively explored with 2D and 3D seismic surveys and many wells. Gravity and magnetic data provide a low cost way to screen large areas as well as construct important alternative models to delineate subsurface structures and reach a better understanding of the geology. The density contrasts presented by the juxtaposition of sediments with shales and salt make detailed gravity modelling in this region a valuable exercise. The magnetic data provide insight into mapping basement surfaces and delineating shallower volcanics and in some cases shale or salt diapers. In the Gulf of Mexico, the reconstruction of the paleo-tectonic history is also enhanced by incorporating the potential field data. New work is ongoing which blends the geologic information with the gravity and magnetic data using regional scale modelling techniques. Gravity and magnetic data have been traditionally thought of as regional screening tools capable of providing basin edges or basement mapping. In recent years, the application of these data has been greatly expanded to include modelling of prospect-level targets.
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Modern storage architectures, mass storage systems, their components and their application in geophysics
By G.N. KolafaSynergy is a common goal in theory and practice within an E&P organization. Due to the vast quantities of data acquired from varied disciplines and the need to assess and analyse this information in line with company targets of quality, time and cost, ‘Information Management’ has become a key issue in achieving these targets and adequate levels of synergy. Geoscientists are confronted daily with managing these data, so that (1) the data do not become lost or ignored and (2) they are not insufficiently analysed or applied for their purpose. This has produced a call for new tools and systems to organize and retrieve these data more quickly and efficiently in order to improve processing, and facilitate decision making. Capacity has also become of paramount importance in the light of the amount of existing data to be incorporated into such systems and, of course, with 3D seismic being common and the increase in 4D seismic, present and future rates of data generation will continue to increase and will have to be coped with. Recent product developments have made it possible to assemble highly integrated systems that address the issues above and provide the right level of flexibility to accomplish high levels of synergy in a very practical form. These particular products and systems will be discussed in this article. The systems are commonly known as Mass Storage Systems or Near-Line Storage and consist of various types of hardware and software for managing uniform or mixed media. Additionally, there are systems for organizing and controlling the information, as well as monitoring media degradation and implementing protective measures against data loss that might result. The development of NAS (Network Attached Storage) and SAN (Storage Area Network) products have brought new considerations into the overall architecture. It is apparent that there has been difficulty integrating these technologies into operations for different reasons and it is hoped that the discussion here will provide some insight and guidance regarding these systems.
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Integration loop of of ‘global offset’ seismic, continuous profiling magnetotelluric and gravity data
More LessIn this paper an approach aimed at integrating many different geophysical/geological data is discussed. It is based on a recursive process of forward and inverse modelling of seismic and non-seismic data. The experimental data set of the Enhanced Seismic In Thrust belts (ESIT) research project, funded by Eni E&P, Enterprise Oil Italiana and the European Union, was used in order to apply the approach to a real case of complex geological setting. Near-vertical reflection seismic, long-offset seismic, high-resolution magnetotelluric, gravity, borehole and surface geological data were involved in the process. We demonstrate how a ‘self-feeding’ integration loop is an efficient way to produce a unique geophysical model that responds to several basic requirements, such as optimized inversion/modelling in each parameter space, best fit in each geophysical domain, best seismic imaging, reliable geological meaning and cost/benefit ratio optimization. Introduction Integration of multiple data sets in complex geological settings represents one of the most challenging objectives in geophysics. This is true especially in the case of geophysical projects based on the acquisition of highly redundant data sets and characterized by many different sources of information. In fact, particularly in complex areas where the quality of standard seismic is poor, alternative non-seismic approaches are required. An exploration strategy based on many different and complementary methodologies always produces a complex data set, and integrating all the information in consistent and reliable models can fail if an appropriate integration strategy is not applied. In previous work (Dell'Aversana & Morandi 2000, 2002; Dell'Aversana 2001), we introduced an integration approach based on recursive forward and inverse modelling of seismic, magnetotelluric and gravity data. We showed that the so- called ‘global offset’ seismic approach (which also includes high-fold, long-offset data) can improve significantly the process of building reliable models by a quantitative integration with MT and gravity data and with the support of borehole information. In a subsequent paper (Dell'Aversana et al. 2002b), we demonstrated how, by applying prestack depth migration to global offset data, it is possible to improve the depth imaging in difficult geological settings, also when the S/N ratio of the conventional near-vertical reflection data is very low. This result can be obtained especially if non-seismic data are used for defining accurate multi-parametric models. These models can contribute to the definition of an appropriate velocity field for seismic data migration, as will be clarified in this paper. In fact, recent experiments and applications showed how the continuous profiling magnetotelluric method can produce reliable resistivity sections that can support both the velocity field definition and the geological interpretation in case of low-quality seismic sections (Zerilli & Dell'Aversana 2002). Here, we continue the discussion about the integration of many data sets, but also introduce several important additional concepts. We take the opportunity offered by the large multiple data set collected during the ESIT research project (Buia et al. 2002; Dell'Aversana et al. 2002b). We demonstrate that an appropriate quantitative integration of global offset seismic, continuous profiling high-resolution magnetotelluric (HRMT), gravity, borehole and geological data is a reliable and cost-effective process. Each source of information contributes to different aspects of the process, due to the varying benefits and limitations of each of the different methodologies used. Based on many different geophysical parameters, the final result is a well-calibrated model that is consistent with the best seismic imaging. The geological consistency is considered as a fundamental requirement at each step of the process.
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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)