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- Volume 37, Issue 4, 2019
First Break - Volume 37, Issue 4, 2019
Volume 37, Issue 4, 2019
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Attribute analysis improvement by means of smart averaging
By D. KrilovAbstractSeismic attribute maps can benefit from dedicated processing for suppression of noise and improvement in geological feature delineation. Traditional 2D windowed frequency filtering, or smoothing, can degrade the required resolution and hence impacts interpretability. We propose a ‘Smart Averaging’ (SA) technique, which is an optimization routine based on specific criteria, and we show that the root mean square (RMS) deviation minimization criterion is effective for both spikes and random noise, providing both visual and interpretation improvement. It out-performs conventional fixed window smoothing, or averaging.
The dependency between interpretation reliability, data resolution and random noise level is demonstrated. When the attribute maps have very high levels of noise, we show that interpretation is still successful, even if the attribute map detail is noticeably compromised.
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Unravelling an anomalous seismic response using seismic modelling: a case study from Cauvery Basin, offshore East Coast India
Authors Minakshi Mishra and Kumar Hemant SinghAbstractSeismic data interpretation and seismic attribute analysis are two fundamental processes in geological model building and reservoir characterization. Detailed analysis of amplitude, phase and frequency plays a vital role in the de-risking of a prospect in terms of reservoir presence and its quality. Here, the significance of forward modelling is illustrated in unravelling an anomalous seismic response in a complex geological set-up through detailed investigation of a prospect in the Cauvery Basin, offshore East Coast of India. The bright anomalous amplitudes of the identified prospect have been modelled using sand and shale properties from offset wells drilled in the basin. A possibility of constructive interference of individual waveforms from various interfaces has been proposed to explain the anomalous amplitudes. The prospect was subsequently drilled and the post-drill results have confirmed the proposed hypothesis. Synthetic modelling using in-situ and edited logs exemplify the concept of interference and its effect on composite amplitudes resulting from summation of individual waveforms. Additionally, post drill analysis of the prospect along with the forward modelling supports the hypothesis of interference.
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Regional appraisal of shale resource potential within the Permian, Anadarko and Arkoma basins: how does the Alpine High stack up?
Authors Alex Bromhead and Thomas ButtAbstractThe Alpine High on the southwestern fringe of the Delaware sub-basin in the Permian Basin (Figure 1) is an emerging unconventional fairway with shale resource potential. In 2016, an operator drilled a series of exploration and appraisal wells on the Alpine High, targeting the stacked resource interval comprising the Woodford, Barnett and Wolfcamp shale plays (Apache Corporation, 2017). All three plays have been successfully developed elsewhere in Texas and/or Oklahoma, but were previously untested on the Alpine High. There are more than 4500 wells targeting the Woodford in the Anadarko and Arkoma basins, more than 24,000 wells targeting the Barnett shale in the Fort Worth Basin and more than 16,000 wells targeting the Wolfcamp in the Delaware and Midland sub-basins of the Permian Basin (Rystad Energy, 2018). The distribution of the wells targeting these shale plays is shown in Figure 1. Initial well results and production tests on the Alpine High are reported to have been promising (Apache Corporation, 2017) and, as a result, the Alpine High is regarded as a highly prospective, but largely untested, unconventional fairway.
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Preventing frac hits and well interferences with fast marching simulation using embedded discrete fracture models constrained by poroelastic geomechanical modelling of enhanced permeability
Authors A. Ouenes, A. Bachir, R. Smaoui, C. Hammerquist and M. ParyaniAbstractInvestors are not happy. A recent article by a major newspaper (Olson et al., 2019) again highlighted the issue of ‘underperforming’ unconventional wells’ production targets. It notes that financial executives from the oil industry state that predicting well performance is an art rather than a science. Others involved in the management of billions of shale assets offer their opinion by noticing that ‘Geology doesn’t line up with Excel spreadsheets too well, unfortunately.’ These sentiments reflect the perceived state of unconventionals’ technology which is reduced to ‘an art and relying on Excel spreadsheets’. Such comments have dramatic consequences on all stakeholders in the unconventional business. A serious consequence came about shortly after the newspaper article was published: a law firm started an investigation targeting executives of an oil company accused of misleading their investors by providing them with false well performance forecasts. Lawyers and financiers quarreling about such highly technical matters put the burden on scientists and engineers to bring practical solutions to this complex problem. During this decade, great efforts have been made to better understand the performance of unconventional wells, but the challenges are overwhelming, and they evolve as our understanding of hydraulic fracturing progresses. Chief among these challenges, we find the issue of frac hits and well interferences.
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The use of the instantaneous phase attribute for monitoring hydraulic fracturing stimulation in the Niobrara Formation, Wattenberg Field, Colorado
Authors Stephen Paskvich and Thomas DavisAbstractIdentifying understimulated areas of unconventional reservoirs is important for developing strategies to maximize field drainages. We use time-lapse multi-component seismic data collected by the Reservoir Characterization Project and Anadarko Petroleum to monitor a hydraulic stimulation in a section of Wattenberg Field, Colorado. We highlight regions of the reservoir where more fractures opened during the stimulation using instantaneous phase to estimate phase differences between pre- and post-stimulation seismic volumes. The remaining areas are interpreted to be understimulated, and analysis of fluid data suggests that the reservoir volume maybe be further drained. Phase shift maps deliver a means to target future infill drilling.
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Hydraulic fracture monitoring and optimization in unconventional completions using a high-resolution engineered fibre-optic Distributed Acoustic Sensor
Authors P. Richter, T. Parker, C. Woerpel, Y. Wu, R. Rufino and M. FarhadiroushanAbstractUnderstanding fracture geometry and estimating stimulated rock volume (SRV) is the goal of operators in unconventional reservoirs. The industry has long been challenged with getting a good understanding of how wells and completions interact with each other. One of the biggest challenges is how to get a quantitative measure of the extent of fractures. Historically, companies have used many different technologies to better understand their completions. Tilt meters, microseismic geophone arrays, chemical tracers and pressure sensors are just some of the conventional technologies that have been used with a limited coverage to monitor the changes in the reservoir during hydraulic fracturing.
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Croatian Pannonian Basin licence round hydrocarbon potential assessment
Authors Karyna Rodriguez, Neil Hodgson and Howard NichollsAbstractWith a proven hydrocarbon system, numerous discoveries and up to 59 oil, gas and condensate fields, the Pannonian basin is one of the most important hydrocarbon provinces in central Europe. Covering an area of 26,000 km, it has one of the deepest sedimentary sections and since the 1940s has produced more than 700 MMBO of oil and more than 400 MMBOE of natural gas.
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Unconventional petroleum potential in the Mowry Shale, Southern Powder River Basin, Wyoming
More LessAbstractThe Lower Cretaceous Mowry Shale is a major source rock in the northern Rocky Mountain region (Schrayer and Zarrella, 1968; Nixon, 1973; Byers and Larson, 1979; Burtner and Warner, 1984; Momper and Williams, 1984; Davis et al., 1989; Modica and Lapierre, 2012). The source rock contains primarily Type II organic matter with an admixture of Type III kerogen towards the west. Thermally mature Mowry Shales are closely associated with petroleum accumulations in both Lower and Upper Cretaceous reservoirs.
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Characteristics of surface wave Green’s function for anisotropic ambient seismic noise field — a case study in Limburg, The Netherlands
Authors Soumen Koley, Henk Jan Bulten, Jo van den Brand, Maria Bader, Frank Linde and Mark BekerAbstractThe Advanced LIGO and the Advanced Virgo gravitational wave (GW) detectors are built on the surface of the earth. Seismic noise being most dominant on the surface limits the low frequency sensitivity of the detectors below 10 Hz. The Einstein Telescope (ET), a European project for constructing a third generation GW detector aims to improve current detector sensitivity by an order of magnitude at frequencies below 10 Hz. One way of reducing the contribution from seismic noise is by building the detector underground. Currently seismic studies are being conducted in Sardinia, Italy and Limburg, The Netherlands, for selecting an appropriate site for constructing the ET. A dense array of 146 wireless vertical component geophones was deployed at Limburg in The Netherlands with the aim of performing passive seismic tomography using the seismic noise in the frequency band 2.5–8.0 Hz. Theoretically for accurate extraction of surface wave Green’s function, an isotropic distribution of noise sources surrounding a station pair is desired. However, in reality the distribution of noise sources manifest azimuthal anisotropy and also vary in source magnitude. In this article, we discuss the results of the accuracy of the extracted surface wave Green’s function when illuminated by an anisotropic distribution of noise sources. We make use of the method of cross-correlation beamforming to extract station pairs that yield accurate surface waves Green’s function and consequently compute the surface wave group velocities for the region.
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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)