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- Volume 36, Issue 5, 2018
First Break - Volume 36, Issue 5, 2018
Volume 36, Issue 5, 2018
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Revisiting Dix’s RMS approximation for Normal Move-Out Velocity
By Huw JamesAbstractThe RMS velocity approximation continues to be used in seismic data processing and interpretation while its limitations are not well understood because its derivation is opaque to most modern geophysicists. One of the reasons for this is because Dix describes in (Dix, 1955) NMO velocity functions determined by T2-X2 analysis of shot records, which very few current geophysicists have ever performed. A clearer understanding of T2-X2 analysis and the derivation of the RMS formula will enable NMO-derived velocities to be better understood and so better used in reflection seismic imaging, inversion and interpretation. Dix’s derivation closely follows the process of correcting the apparent depth from say refraction of objects in water when viewed from the air. So it is useful to search for this subject and follow the development which relies on the observer’s eye separation being small relative to the depth of the object and also relies on refraction being towards the normal of any interface so that angles of incidence will reduce and remain small. This is true for light because the speed of light in water is much slower in water than in air. Reflection seismic uses sound which in general bends away from the normal at each interface as sound velocities tend to increase with depth so that angles of incidence increase which causes a problem with the method which we will see later.
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Structurally oriented coherent noise filtering
More LessAbstractAll seismic data, whether 2D, 3D, post-stack or pre-stack, contains noise. Typically, this noise is comprised of both coherent and random components. Coherent noise presents itself as regular patterns in the seismic data. It may appear to be random or coherent depending on the orientation of the slice on which it is being observed. For example, coherent noise associated with acquisition may appear random on vertical slices through the volume, with its coherent nature becoming apparent on horizontal slices through the volume.
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GLCM-based anisotropy estimation — the influence of computation parameters on the results
Authors Christoph Georg Eichkitz and Johannes AmtmannAbstractThe grey level co-occurrence matrix (GLCM) is a second-order statistical texture classification method initially described by Haralick et al., (1973). Typically, two neighbouring images are compared by using a moving analysis window to construct a 2D GLCM. This is used subsequently in the calculation of GLCM-based attributes. Common applications of GLCM attributes include classification of satellite images (Franklin et al., 2001; Tsai et al., 2007) and images based on magnetic resonance or computed tomography (Kovalev et al., 2001; Zizzari et al., 2011). GLCM has played a minor role in seismic interpretation, but within the last 20 years several authors have used the GLCM method to interpret channels systems (Eichkitz et al., 2013, 2014, 2015a, 2015b, 2016; West et al., 2002; Gao, 2007, 2011; de Matos et al., 2011), sedimentary facies (Di and Gao, 2017; Eichkitz, et al., 2012; Chopra and Alexeev, 2005, 2006a, 2006b; Yenugu et al., 2010; Wang et al., 2016), salt bodies (Gao, 2003), and fractures (Eichkitz et al., 2015c, 2016; Schneider et al., 2016). Most of these studies focus on direct extraction of information from GLCM-based attributes.
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Understanding frequency decomposition colour blends using forward modelling — examples from the Scarborough gas field
By Chris HanAbstractFrequency Decomposition (FD) colour blending of 3D seismic data has become a mainstream technique used by oil and gas industry G&G specialists for imaging subsurface geology. The workflow involves creating frequency band-restricted components of the seismic data and blending these together into a single volume, typically using a three-dimensional, red-green-blue (RGB) colour scheme. The blends often produce high-resolution, detailed images capable of detecting very subtle features owing to the interference between three frequency band components which tune at different frequencies. A major advantage is being able to assess distribution and extrapolation of results away from well locations since the results are volumetric and not restricted to a well location. The workflow has typically been applied in a qualitative manner to identify depositional features, structures and geomorphologies visually based on colour changes in the blends. However, the link between the colours and rock physics is poorly understood.
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Seismic anisotropy estimation of the Talang Akar formation in south Sumatra basin, Indonesia, using ultrasonic tomography in core plugs
Authors Vani Mutia Sari, Sigit Sukmono, Teuku Abdullah Sanny and Benyamin SapiieAbstractThe South Sumatra Basin is one most prolific hydrocarbon provinces in Indonesia (Figure 1) with estimated known petroleum resources of 4.3 billion barrels of oil equivalent (bboe) (Klett et al., 1997). Talang Akar Formation (TAF) is the main source and reservoir rock in the basin (Sarjono and Sardjito, 1989; Sosrowidjojo et al., 1994). It accounts for more than 75% of the cumulative oil production in the province and has approximately 2 bboe ultimate recoverable reserves (Tamtomo et al., 1997).
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Reinterpreting the South Atlantic Pre-Salt ‘Microbialite’ reservoirs: petrographic, isotopic and seismic evidence for a shallow evaporitic lake depositional model
Authors Paul Wright and Karyna RodriguezAbstractThe first encounter of the Pre-Salt Aptian ‘Microbialite’ carbonate reservoirs (the Barra Velha Fm) in 2005, in the Parati field, Santos Basin, was followed by additional discoveries such as the multi-billion barrel Lula (Tupi) field. Now, nearly 30 more discoveries have been made in the basin such as Libra and Sapinhoa, with recoverable reserves estimated as >30 BBOE, according to ANP. In addition, discoveries have been made in the adjacent Campos Basin, including the Pão de Açúcar field (Viera de Luca et al., 2017), where the same unit is known as the Macabu Fm., and also in the Kwanza Basin, West Africa (Saller et al., 2016). After deposition in a late rift setting, the Barra Velha Fm and its equivalents were buried by more than 1 km of marine origin evaporites of the Ariri Fm and its equivalents, as the Albian Ocean seeped and poured into the basin.
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Joint inversion of multi-component seismic data: application to Bakken petroleum exploration and development
Authors Kritti Kreeprasertkul and Thomas L. DavisAbstractThe Reservoir Characterization Project (RCP) at Colorado School of Mines acquired the rights to a 9C, 3D seismic survey in Mountrail County, North Dakota with specific focus on how multi-component seismic data could aid in exploration and development of the Bakken Shale (Figure 1). Proximity to the giant Parshall Field made the survey particularly attractive as operators in the Bakken wanted to find if additional value could be created by acquiring multi-component seismic data in this major unconventional resource play.
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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)