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The natural logarithm of the ratio of two amplitudes is measured in nepers. By definition, if Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") One bel 10 decibels (dB), and energy is proportional to (amplitude)Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Let Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.")
- Information Technology > Knowledge Management (0.76)
- Information Technology > Communications > Collaboration (0.76)
This means each frequency component travels at a different speed; namely, the horizontal phase velocity. The dispersive character of guided waves is most pronounced in shallow water environments (less than 100 m). Depending on various water-bottom conditions, such as a mud layer with variable thickness or a hard bottom, the character of these waves may vary from shot to shot (Figure 6.0-3). They also can cause linear noise on stacked data (Figure 6.2-8a) and are easily confused with the linear noise that is associated with side scatterers (Figure 6.0-4). McMechan and Yedlin [4] proposed a way to obtain phase velocity information from field data.
- Information Technology > Knowledge Management (0.76)
- Information Technology > Communications > Collaboration (0.76)
The scientific research process begins as one tries to find explanations for a phenomenon. We make observations, define the problem statement, and review the existing domains of research that could be used. Another approach is to explore theoretical problems, those that are purely conceptual at present but provide a solution when a related observation is made in the future. Though these approaches sound isolated, both are part of characterizing uncertainty, and uncertainty comes in all scales and dimensions. This challenges us to learn at all scales possible, from the fume hoods in the laboratory to magnificently exposed outcrops and through deep narrow boreholes that drill through subsurface reservoirs. The combined efforts often convert learnings to actionable intelligence. At a smaller scale, porosity and permeability are probably the two most-studied rock properties among those that have meaningful implications for hydrocarbon reservoirs. Paper SPE 216856 considers machine-learning (ML) methods for classifying reservoir texture at a microscale. Borehole-image logs long have been used to obtain a picture of subsurface reservoirs. Unfortunately, a majority of the observations are qualitative. Quantifying these features faces the challenge of continuity, upscaling, and regional correlation. As we explore the latitude of ML-based applications, the use of these techniques for quantifying image logs becomes very relevant. The authors of that paper contribute to quantifying textural features at a โfume-hood scaleโ and develop a work flow with the potential for estimating properties such as porosity and permeability from a different domain of reservoir characterization. I often wonder how much the domain on formation evaluation encompasses. While geoscience-driven reservoir characterization is a big part of it, how reservoirs change over time also is a complementary observation. Paper URTeC 3864861 discusses various aspects of geomechanical changes that a hydraulically fractured reservoir goes through during its life cycle. The authors here study the relationship between measured strain from the fiber-optic sensors and wellhead pressure. Research like this could be extended to predicting production profiles and estimating recovery factors, which are important considerations in designing a stimulation program for sustaining production, maximizing recovery, and improving financial matrices for the capital program. I believe information could be categorized as learning, knowledge, and intelligence. Any scientific process starts with set of careful observations bound by an envelope of hypotheses. This is learning. Learning, which could be verified by predictable and repeatable outcomes from carefully designed experiments of complementing domains, becomes knowledge. Actionable knowledge, which then could be used to alter an outcome or a process, becomes intelligence. Paper URTeC 3871303 discusses a development strategy in a restrictive development unit with an existing parent well. Here, considerations are heavily weighted toward optimizing both interwell spacing and capital efficiency. The search for answers to a problem like this must seek guidance from a variable-scale experiment. The study here establishes the big picture with the structural elements of the basin that could restrict both the continuity of the reservoir and the nature of the producible fluid. With this framework, the model is then set to iterate from several different perspectives. Potential interwell communications are explored by measuring fracture-driven interactions (FDIs) and quantifying stimulated reservoir volume. What is impressive here is the different domains from which the authors seek answers. Direct observations from acoustic-fiber measurements for FDI and the geochemistry of produced fluids for identifying unique signatures from vertically separated formations are individual domains that seek the same answers in various scales. The study recommends the optimal spacing between wells and a stimulation design that minimizes well interference, reduces competition for resources between wells, and avoids overcapitalizing the program. This is how knowledge transforms into intelligence. I hope the readers appreciate the scales of characterization in these three papers. As a student of geology, I have always been fascinated by the concept of scale and its relation to the domains of science that we deal with. Unlike general relativity and quantum mechanics, most geologic phenomena are observed in all scales. It is just the uncertainty that needs to be quantified.
Experimental seismic crosshole setup to investigate the application of rock physical models at the field scale
Birnstengel, Susann (Helmholtz Centre for Environmental Research) | Dietrich, Peter (Helmholtz Centre for Environmental Research) | Peisker, Kilian (Helmholtz Centre for Environmental Research) | Pohle, Marco (Helmholtz Centre for Environmental Research) | Hornbruch, Gtz (Christian Albrechts Universitt zu Kiel) | Bauer, Sebastian (Christian Albrechts Universitt zu Kiel) | Hu, Linwei (Christian Albrechts Universitt zu Kiel) | Gnther, Thomas (Leibniz Institute for Applied Geophysics) | Hellwig, Olaf (TU Bergakademie Freiberg) | Dahmke, Andreas (Christian Albrechts Universitt zu Kiel) | Werban, Ulrike (Helmholtz Centre for Environmental Research)
Seismic crosshole techniques are powerful tools to characterize the properties of near-surface aquifers. Knowledge of rock-physical relations at the field scale is essential for interpreting geophysical measurements. However, it remains difficult to extend the results of existing laboratory studies to the field scale due to the usage of different frequency ranges. To address this, we develop an experimental layout that successfully determines the dependency of gas saturation on seismic properties. Integrating geophysical measurements into a hydrogeological research question allows us to prove the applicability of theoretical rock physical concepts at the field scale, filling a gap in the discipline of hydrogeophysics. We use crosshole seismics to perform a time lapse study on a gas injection experiment at the TestUM test site. With a controlled two-day gaseous CH4 injection at 17.5ย m depth, we monitor the alteration of water saturation in the sediments over a period of twelve months, encompassing an observational depth of 813m. The investigation contains an initial P-wave simulation followed by a data-based P-wave velocity analysis. Subsequently, we discuss different approaches on quantifying gas content changes by comparing Gassmanns equation and the time-average relation. With the idea of patchy saturation, we discover that analyzing P-wave velocities in the subsurface is a suitable method for our experiment, resulting in a measurement accuracy of 0.2ย vol.%. We demonstrate that our seismic crosshole setup is able to describe the relation of the rocks elastic parameter on modified fluid properties at the field scale. With this method, we are able to quantify relative water content changes in the subsurface.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (1.00)
Instantaneous frequency is Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Instantaneous frequency can be thought of as the frequency of the complex sinusoid that locally best fits a complex trace. Used to determine seismic attributes. In the space domain, "local" is sometimes used instead of "instantaneous". See Figure C-11 y Taner et al. (1979).
Geophysicists are often turned off by equations. This is unfortunate because equations are simply compact, quantitative expressions of relationships, and one should make an effort to understand the information that they convey. They tell us what factors are important in a relationship and their relative importance. They also suggest what factors are not relevant, except perhaps through indirect effects on the relevant factors. Graphs often help us visualize equations more clearly.
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Volcanology is the study of volcanic formation, activity, and related products of volcanoes. As a science volcanology implores a wide range of geologic sub disciplines from seismology to infrasound applications. In relation to geophysics volcanology primarily is used to study internal characteristics and features of the subsurface of the earth, and their relation to volcanic phenomena. Large scale processes such as plate tectonics and regional/global mantle behavior are used to help understand volcanology in a wholistic geological sense, however the science itself has been in existence as far back as ancient times.[1] Volcanology groups volcanoes into three groups based on historical activity: active, dormant, and extinct, each having certain features which separate them from one another.
- Geology > Geological Subdiscipline > Volcanology (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.40)
The Vetlesen Prize is awarded from Columbia University's Lamont-Doherty Earth Observatory and the G. Unger Vetlesen Foundation. The Vetlesen Prize has been described as an attempt to establish an equivalent of a Nobel award for geophysics[1] or geology.[2] The prize is awarded for scientific achievement resulting in a clearer understanding of the Earth, its history, or its relations to the universe. The prize was established in 1959 and is awarded on average once every two years, if the jury selects at least one worthy candidate during this period.[3] G. Unger Vetlesen established the foundation which bears his name shortly before his death in 1955. In addition to the Vetlesen Prize, the foundation provides support in the Earth sciences for institutions of excellence.
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Equation (4.3a) for an offset geophone can be written To get the coordinates of A ( x, z) {\displaystyle A(x,z)}, a point on I G {\displaystyle IG}, we draw A B {\displaystyle AB} and I C {\displaystyle IC} perpendicular to T G {\displaystyle TG} . We now solve equations (4.11c) and (4.11f) as simultaneous equations. From equation (4.11f) we get
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)