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  • 1
    Electronic Resource
    Electronic Resource
    Upper-crustal strength inferred from stress measurements to 6 km depth in the KTB borehole (1993)
    [s.l.] : Nature Publishing Group
    Nature 365 (1993), S. 633-635 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The KTB (Kontinentales Tiefbohrprogramm der Bundesrepu-blik Deutschland) drillsite is located in an area of occasional minor seismicity where highly deformed Palaeozoic meta-morphic rocks have been intruded by Variscan (late Palaeozoic) granites. In the first phase of the drilling project ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/365633a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Aspects of the theory of relational languages for data processing (1984)
    Springer
    Cybernetics and systems analysis 20 (1984), S. 659-666 
    Details
    ISSN: 1573-8337
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Conclusions ERA and β-calculus are relational languages of data processing. Obviously, some mathematical training is necessary to solve problems in such languages. These languages are unacceptable for lay users. On the other hand, ERA and β-calculus can provide a mathematical basis for developing procedural and declarative data processing languages convenient, for use. In particular, ERA has served as the basis for developing a psychologically convenient language Ryaod [8, 9] by the Institute of Cybernetics of the Academy of Sciences of the Ukrainian SSR and the Ukrainian Institute of Psychology, intended for data processing on computer by lay users. The Ryaod language is convenient in description of data processing problems, user formulation of the solution process, planning and execution of solutions, process control, and man-machine commication. The aggregate units of language operators and the linearity of the Ryaod program facilitate program adjustment and accelerate software development. The psychologically convenient language Dnepr [10] is based on β-calculus. The language is intended for performance of untypical data processing functions with the use of a data base. Dnepr is more effective for such tasks than Ryaod because data descriptions are not included in the application program, the language sentences are more compact, and the language which is oriented for operation with a video display can be learned faster. Compared with the other existing relational languages, Ryaod and Dnepr have a larger inventory of functional and service tools.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01071610
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  • 3
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    Physical bounds on C 13 and δ for organic mudrocks (2018)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2018
    Description: 〈span〉〈div〉ABSTRACT〈/div〉We have used a reliable, updated database of ultrasonic measurements on organic mudrocks that contains components {Cij} of the transversely isotropic elastic tensor, and hence the Thomsen’s anisotropy parameters ϵ and δ, to establish a more useful upper bound of feasible values for C13, and hence δ in unconventional mudrock reservoirs than that introduced earlier. The new upper bound δmax=ϵ is consistent with elliptical anisotropy and represents a much better constraint for these mudrocks. We derive the upper bound C13max (and hence δmax) from Postma’s inequality applicable to a thin-layered effective medium composed of kerogen and inorganic phases. The anisotropic moduli of such a composite as given by the Postma-Backus model are well-matched by the experimental data at least in the bedding-normal direction. As for the lower bound δmin, which was suggested by others, we confirm its reliability and usefulness for organic mudrocks.〈/span〉
    Print ISSN: 0016-8033
    Electronic ISSN: 1942-2156
    Topics: Geosciences , Physics
    Published by Society of Exploration Geophysicists (SEG)
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  • 4
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    Rock-physics model for unconventional shales (2014)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2014-03-05
    Description: An analytic model was adopted to calculate bedding-normal, dry elastic moduli of rocks enriched with solid organic matter — kerogen. Elastic stiffnesses in the model are functions of solid matrix moduli, total porosity, pore-shape factor, and crack density. Crack density is taken to be an exponential decay function of stress, which was calibrated using ultrasonic core measurements, whereas pore-shape factor was calibrated using sonic logs. Bedding-normal, fluid-saturated moduli were computed by means of Gassmann's equation, i.e., ignoring anisotropy. As a result, a model to calculate elastic moduli of organic shales was constructed and used for sonic-velocity prediction and pore-pressure calibration. Among other things, the model established the fact that the saturating fluid effect on elastic properties in organic shales can be noticeable, especially at extremely low effective stress. However, it is the kerogen content that is largely responsible for the anomalous deviation of log data points from conventional shale trend toward the hydrocarbon-charged sandstone trend in the acoustic- versus shear-impedance (AI–SI) domain.
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists (SEG)
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  • 5
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    Introduction to this special section: Rock physics (2019)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2019
    Description: 〈span〉〈div〉Abstract〈/div〉Rock physics links the physical properties of rocks to geophysical and petrophysical observations and, in the process, serves as a focal point in many exploration and reservoir characterization studies. Today, the field of rock physics and seismic petrophysics embraces new directions with diverse applications in estimating static and dynamic reservoir properties through time-variant mechanical, thermal, chemical, and geologic processes. Integration with new digital and computing technologies is gradually gaining traction. The use of rock physics in seismic imaging, prestack seismic analysis, seismic inversion, and geomechanical model building also contributes to the increase in rock-physics influence. This special section highlights current rock-physics research and practices in several key areas, namely experimental rock physics, rock-physics theory and model studies, and the use of rock physics in reservoir characterizations.〈/span〉
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists (SEG)
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  • 6
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    Introduction to this special section: Resource plays I: Rock physics (2015)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2015-11-05
    Description: When we began to soliciti papers for this special section of The Leading Edge on "Resource plays I: Rock physics," we debated among ourselves the definition of resource plays and what articles we should be looking for. We also searched for how others define the term resource plays and have come to realize that it is more of an economic term associated with volume and risk rather than its geologic characteristics.
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists (SEG)
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  • 7
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    Constraining seismic rock-property logs in organic shale reservoirs (2015)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2015-11-05
    Description: One of the major challenges of unconventional shale reservoirs is to understand the effects of organic richness (total organic carbon, TOC), mineralogy, microcracks, pore shape, and effective stress on elastic properties. The generation of petrophysical parameters, such as TOC, and quantification of total and organic porosities through a physically consistent petrophysical model are described. Rock-matrix density, which is a key parameter in determining total porosity, is estimated as a function of the amount of TOC and its level of maturity. Then the petrophysical parameters are used as inputs for rock-physics modeling to constrain the bedding-normal compressional-wave velocity as a function of various parameters (e.g., TOC, porosity, mineralogy, pore shapes, and microcrack density) in combination with effective stress. Modeling results on three shale plays from North America show that compressional-wave velocity in these specific formations is controlled mainly by variations in TOC, mineralogy, and pore shape. Shear-wave velocity in organic shales also was refined as a function of compressional-wave velocity and amount of TOC.
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists (SEG)
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  • 8
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    Testing popular rock-physics models (2019)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2019
    Description: 〈span〉〈div〉Abstract〈/div〉In the spirit of classic rock physics, and as an ideal foundation for conventional quantitative interpretation workflows, we consider several popular models relating elastic rock properties to their composition, microstructure, and effective stress on the background of a worldwide log data set, incorporating sands and shales characterized by the maximum dynamic impedance range. We demonstrate that the patchy cement model, ellipsoidal inclusion model, and siliciclastic diagenesis model may be calibrated successfully against the world data set and used in seismic rock property log restoration/editing. We also demonstrate that some of these models present obvious challenges in terms of the information derived from quantitative seismic interpretation. Notably, the key input parameters used in these rock-physics models may show little resemblance to the rock parameters actually observed in geologic studies. Replacing the true rock parameters with the effective ones may do disservice to the science of rock physics in general.〈/span〉
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists (SEG)
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  • 9
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    Seismic inversion for organic richness and fracture gradient in unconventional reservoirs: Eagle Ford Shale, Texas (2015)
    Society of Exploration Geophysicists (SEG)
    Details
    Publication Date: 2015-01-01
    Description: A method using Eagle Ford organic shale from Texas predicts key unconventional reservoir properties, total organic carbon (TOC), and fracture pressure gradient (FG). Applying petrophysical and rock-physics models from previous work to the available well-log data generates the required logs for calibration, i.e., shear sonic, TOC, organic porosity, and saturation. Prestack seismic data can be evaluated using synthetic forward modeling and can be conditioned further to improve AVO response. Simultaneous prestack inversion to derive acoustic-impedance (AI) and shear-impedance (SI) volumes can be run, and TOC can be derived from those volumes by linear interpolation. Fracture gradient (which also can be thought of as "frackability") is related directly to Poisson's ratio and effective stress and can be estimated from elastic properties. The fracture gradient is related nonlinearly and inversely to TOC, i.e., assuming laterally and vertically homogeneous pore-pressure distribution inside the spatially limited block of the Eagle Ford Shale, higher TOC results in lower FG and hence better frackability.
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists (SEG)
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  • 10
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    Estimation of net-to-gross fromPandSimpedance in deepwater turbidites (2002)
    Society of Exploration Geophysicists
    Details
    Publication Date: 2002-04-01
    Print ISSN: 1070-485X
    Electronic ISSN: 1938-3789
    Topics: Geosciences
    Published by Society of Exploration Geophysicists
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