scholarly journals Spatial orientation and distribution of reservoir fractures from scattered seismic energy

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. O43-O51 ◽  
Author(s):  
Mark E. Willis ◽  
Daniel R. Burns ◽  
Rama Rao ◽  
Burke Minsley ◽  
M. Nafi Toksöz ◽  
...  
Keyword(s):  
Transfer Function ◽  
Seismic Waves ◽  
Transfer Functions ◽  
Full Range ◽  
Seismic Energy ◽  
Field Measurements ◽  
Discrete Systems ◽  
Fractured Reservoir ◽  
Fracture Spacing ◽  
The Difference

We present the details of a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations we have made from 3D finite-difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fracture corridors impart a coda signature, which is a ringing tail of scattered energy, to any seismic waves which are transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: (1) the difference in angle between the orientation of the fractures and the acquisition direction, (2) the fracture spacing, (3) the wavelength of the illuminating seismic energy, and (4) the compliance, or stiffness, of the fractures. This coda energy is most coherent when the acquisition direction is parallel to the strike ofthe fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. Our method uses surface seismic reflection traces to derive a transfer function that quantifies the change in an apparent source wavelet before and after propagating through a fractured interval. The transfer function for an interval with no or low amounts of scattering will be more spikelike and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. When a 3D survey is acquired with a full range of azimuths, the variation in the derived transfer functions allows us to identify subsurface areas with high fracturing and to determine the strike of those fractures. We calibrated the method with model data and then applied it to the Emilio field with a fractured reservoir. The method yielded results which agree with known field measurements and previously published fracture orientations derived from PS anisotropy.

scholarly journals Cross-site investigation on head-related and headphone transfer functions: variabilities in relation to loudness balancing

Acta Acustica ◽  
2021 ◽  
Vol 5 ◽  
pp. 58
Author(s):  
Michael Kohnen ◽  
Florian Denk ◽  
Josep Llorca-Bofi ◽  
Birger Kollmeier ◽  
Michael Vorländer
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Site Investigation ◽  
Limited Range ◽  
The Difference ◽  
Lower Variability ◽  
Set Up ◽  
Insert Earphones ◽  
High Repeatability ◽  
Cross Site

Headphone transfer function (HpTF) and head-related transfer function (HRTF) measurements are crucial in acoustic science and in binaural virtual acoustic applications. Yet, their measurement set-up, procedure or post-processing is different for nearly every lab, especially for the HRTF measurements. To compare findings between different labs, these measurement deviations have to be quantified alongside with their influence on perceptual aspects. In the scope of a cross-site investigation on loudness balancing between headphone and loudspeaker listening, a set of HpTFs with three different headphones (open, closed, insert earphones) and HRTF close to the eardrum were measured in 14 participants travelling to two different measurement sites at Aachen and Oldenburg. Though set-ups for measuring the HRTF are very different between sites, the gathered HRTFs are quite consistent across them. For the measured HpTFs, across sites the open headphones consistently yield a slightly lower variability in the range from 70 to 5000 Hz than the closed one while the insert earphones exhibit much higher variabilities and a limited range of reproducible results. The difference in loudness balancing across labs could well be predicted by site-specific systematic differences in HpTFs with the exception of 1 kHz narrowband stimulus. This clearly indicates the limits in comparability of HpTFs and loudness balancing across labs and the importance of using headphones with high repeatability like the open ones used in this investigation.

scholarly journals Streamline simulation of water-oil displacement in a heterogeneous fractured reservoir using different transfer functions

2018 ◽  
Vol 73 ◽  
pp. 14 ◽  
Author(s):  
Mohammad Mesbah ◽  
Ali Vatani ◽  
Majid Siavashi
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Water Saturation ◽  
Fractured Reservoirs ◽  
Rock Properties ◽  
Fractured Reservoir ◽  
Commercial Software ◽  
The Matrix ◽  
Eulerian Grid ◽  
Streamline Method

Main parts of oil and gas reserves are stored in fractured reservoirs. Simulation of multiphase flow in fractured reservoirs requires a large amount of calculations due to the complexity, reservoir scale and heterogeneity of the rock properties. The accuracy and speed of the streamline method for simulating hydrocarbon reservoirs at field scale make it more applicable than conventional Eulerian simulators using finite difference and finite element techniques. Conventional simulators for fractured reservoirs consume a great deal of time and expense and require powerful CPUs like supercomputers. This makes the development of a fast, powerful and precise simulation method of great importance. The present study was undertaken to develop a computational code as a streamline simulator to study waterflooding in a two-dimensional fractured reservoir with heterogeneous permeability using the Dual Porosity-Single Permeability (DPSP) model. In this simulator, the pressure equation is solved implicitly over an Eulerian grid and then the streamlines are generated using Pollock's semi-analytical method and are traced. At this point, the Time-Of-Flight (TOF) is developed and the saturation equations are mapped and solved explicitly along the streamlines. Next, the results are transferred back onto the Eulerian grid and the calculations are repeated until the simulation end time. In fractured reservoirs, the interaction between the matrix and fracture is included in the transfer functions. Transfer functions model fluid flow and production mechanisms between the matrix and fracture. They introduce source/sink equations between the matrix and fracture and they are distributed throughout the media. In the current study, a problem is simulated using streamline method and several important transfer functions. A new linear transfer function with a constant coefficient is introduced that is based on differences in water saturation between the matrix and fracture. The simulation results were then compared and a commercial software is applied to solve the same problem. The results of the streamline simulator were compared with those of the commercial software and showed appropriate accuracy for the newly introduced transfer function. The accuracy and efficiency of the streamline simulator for simulation of two-phase flow in fractured reservoirs using different transfer functions are confirmed and the results are verified.

scholarly journals A difference in a transfer function of two horizontal components between the ground level and the borehole at KiK-net Mashiki Station Anisotropy of shear wave propagation in Kyushu area based on seismic interferometry

2020 ◽  
Author(s):  
Kentaro Motoki ◽  
Kenichi Kato
Keyword(s):  
Transfer Function ◽  
Travel Time ◽  
Transfer Functions ◽  
Source Region ◽  
Seismic Interferometry ◽  
Polarization Direction ◽  
S Wave ◽  
Before And After ◽  
The Difference ◽  
Kyushu District

Abstract In this study, we evaluated the travel time of S-wave between the vertical array stations based on seismic interferometry, focusing on the difference in transfer function due to two horizontal components at the KiK-net Mashiki station (KMMH16). At that time, we surveyed the differences by back azimuth (BAZ) and the polarization direction of seismic waves. Furthermore, we expanded the survey to all KiK-net stations in the Kyushu district, to confirm whether the phenomena seen at KMMH16 is specific to this location. The result shows that the difference by the polarization direction in the travel time was larger than the difference by the BAZ. This result suggests that the difference in transfer function at KMMH16 were affected by the anisotropy of the S-wave velocity. We evaluated the leading S-wave polarization directions (LSPDs) and the strength of anisotropy (ΔV) for all KiK-net stations in the Kyushu district. The LSPDs roughly correspond to the results of previous studies. The LSPDs in the forearc area are nearly perpendicular to the crustal deformation whereas those in the back-arc area are nearly parallel to it. This characteristic is similar to one found by Nakajima and Hasegawa (2008) in the Tohoku district. We examined the change in anisotropy before and after the Kumamoto earthquake at two stations, KMMH16 and KMMH14 that are located near the source region. The changes in the LSPD and the ΔV before and after the earthquake were not notable. At stations that observed weak anisotropy, transfer functions of two horizontal components show similar shape. At stations that observed strong anisotropy, however, the shape of the transfer function differs greatly, depending on the horizontal direction. This suggests that an evaluation of site amplification using a single velocity model may reduce the reproducibility of ground motions.

scholarly journals A difference in a transfer function of two horizontal components between the ground level and the borehole at KiK-net Mashiki Station Anisotropy of shear wave propagation in Kyushu area based on seismic interferometry

2020 ◽  
Author(s):  
Kentaro Motoki ◽  
Kenichi Kato
Keyword(s):  
Transfer Function ◽  
Travel Time ◽  
Transfer Functions ◽  
Source Region ◽  
Seismic Interferometry ◽  
Polarization Direction ◽  
S Wave ◽  
Before And After ◽  
The Difference ◽  
Kyushu District

Abstract In this study, we evaluated the travel time of S-wave between the vertical array stations based on seismic interferometry, focusing on the difference in transfer function due to two horizontal components at the KiK-net Mashiki station (KMMH16). At that time, we surveyed the differences by back azimuth (BAZ) and the polarization direction of seismic waves. Furthermore, we expanded the survey to all KiK-net stations in the Kyushu district, to confirm whether the phenomena seen at KMMH16 is specific to this location. The result shows that the difference by the polarization direction in the travel time was larger than the difference by the BAZ. This result suggests that the difference in transfer function at KMMH16 were affected by the anisotropy of the S-wave velocity. We evaluated the leading S-wave polarization directions (LSPDs) and the strength of anisotropy (ΔV) for all KiK-net stations in the Kyushu district. The LSPDs roughly correspond to the results of previous studies. The LSPDs in the forearc area are nearly perpendicular to the crustal deformation whereas those in the back-arc area are nearly parallel to it. This characteristic is similar to one found by the previous research in the Tohoku district. We examined the change in anisotropy before and after the Kumamoto earthquake at two stations, KMMH16 and KMMH14 that are located near the source region. The changes in the LSPD and the ΔV before and after the earthquake were not notable. At stations that observed weak anisotropy, transfer functions of two horizontal components show similar shape. At stations that observed strong anisotropy, however, the shape of the transfer function differs greatly, depending on the horizontal direction. This suggests that an evaluation of site amplification using a single velocity model may reduce the reproducibility of ground motions.

Influence of Fuel-Air Mixing on Flame Dynamics of Premixed Swirl Burners

2014 ◽  
Author(s):  
Stefanie Bade ◽  
Michael Wagner ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer ◽  
Bruno Schuermans
Keyword(s):  
Transfer Function ◽  
Equivalence Ratio ◽  
Transfer Functions ◽  
Detailed Comparison ◽  
Acoustic Oscillation ◽  
Modular System ◽  
Time Behavior ◽  
Flame Dynamics ◽  
Air Mixing ◽  
The Difference

The influence of fuel-air mixing on the flame dynamics of premixed swirl flames is investigated comparing flame transfer functions determined for perfectly premixed (PP) and technically premixed (TP) operation. In PP operation fuel and air are mixed far upstream of the burner so no equivalence ratio fluctuations appear during thermo-acoustic oscillation. In TP operation the fuel is injected in the swirler slots so equivalence ratio fluctuations occur. The employed swirl burner is a modular system that consists of a swirler and a mixing tube with three different lengths. It was investigated in an atmospheric single burner test rig equipped for flame transfer matrix measurements. Flame transfer function data are presented for both the PP and the TP operation for a variation of power at fixed equivalence ratio and a variation of equivalence ratio for constant power. The unforced flame shapes corresponding to these operation points were acquired and analyzed for scaling parameters of the flame response. It was found that a basic frequency scaling can be achieved for both operation modes using the nominal burner velocity and the flame stand-off distance. A detailed comparison of the PP and TP flame transfer functions is performed for the three different mixing tubes at one operation point. Finally the difference between the PP and the TP flame transfer function is presented and discussed. It is shown that the influence of equivalence ratio fluctuations exhibits a generalized delay time behavior.

scholarly journals Developed Transfer Function Allows Hydro Generators to Enter the Full Range of Ancillary Services Market

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 397
Author(s):  
Paulius Cicėnas ◽  
Virginijus Radziukynas
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Renewable Energy Sources ◽  
Storage System ◽  
Full Range ◽  
Parametric Identification ◽  
Energy Storage System ◽  
Ancillary Services ◽  
Ancillary Services Market ◽  
The Stability

As the number of available renewable energy sources has increased annually, there has been a corresponding rise in the levels of pollution created by traditional electricity generation, ultimately contributing to breaking down the stability of the electrical system at large. Therefore, there is an increasing need to integrate the use of nonpolluting electricity sources, such as pumped storage hydropower plants (PSHP), to ensure the stability of the power system and to maintain the frequency of the system from year-to-year. This paper addresses the issue of PSHP being unsuitable for providing Frequency Containment Reserve (FCR) services and proposes real measurements of the aggregation approach to obtain different data arrays. Based on this, the proposed methodology is orientated toward obtaining transfer functions that were developed using the parametric identification models, and the efficiency of these functions was thoroughly investigated. The proposed transfer function in this paper, in combination with battery energy storage system (BESS) technologies, would allow PSHP technologies to occupy a space in the ancillary services market by providing FCR, Frequency Restoration Reserve (FRR), and Replacement Reserve (RR) services. The performance of the function activated in the BESS is positively validated using the Simulink modeling environment.

Routh Approximations for Reducing Order of Discrete Systems

1982 ◽  
Vol 104 (1) ◽  
pp. 107-109 ◽  
Author(s):  
Chyi Hwang ◽  
Yen-Ping Shin
Keyword(s):  
Transfer Function ◽  
Approximation Method ◽  
Transfer Functions ◽  
Discrete Systems ◽  
Higher Order ◽  
Order System ◽  
High Order System ◽  
Numerical Example ◽  
Higher Order Terms ◽  
Z Domain

Routh approximation method is extended to the simplification of z-transfer functions. The procedure includes (1) transformation of the z-transfer function into the w-domain, (2) γ-δ expansion of the w-transfer function, (3) truncation the higher-order terms in the γ-δ expansions, and (4) transformation of the reduced w-transfer function into the z-domain. The reduced model is always stable if the original high-order system is stable. A numerical example is inclinded to illustrate the procedure.

scholarly journals Seismic response of a layered soil deposit with inclusions

2021 ◽  
Vol 43 (2) ◽  
pp. 3-13
Author(s):  
O.V. Kendzera ◽  
S.V. Mykulyak ◽  
Yu.V. Semenova ◽  
I.A. Skurativska ◽  
S.I. Skurativskyi
Keyword(s):  
Transfer Function ◽  
Seismic Waves ◽  
Transfer Functions ◽  
Boundary Value ◽  
Numerical Procedure ◽  
Layered Soil ◽  
Layered System ◽  
Earthquake Resistant ◽  
Soil Deposits ◽  
The Impact

It is known that soil massifs can amplify or weaken seismic waves generated by earthquakes. Therefore, the problem of studying the impact of soil deposits on the passage of seismic waves is important in terms of the facilities in operation and the design of new earthquake-resistant objects. Soil deposits, which are allotted for building, are mainly layered. In addition, the materials in these layers are also significantly heterogeneous. To describe the dynamics of inhomogeneous soil massif, the model of an elastic continuum with oscillating non-interacting inclusions is used. Within the framework of this model, the resonant properties of multi-layered soil deposit are analyzed at the conditions of harmonic perturbations applied to the bedrock. On the basis of the solution to the boundary value problem concerning oscillations of the system subjected to the free surface and conjugation conditions on the boundaries between layers, it is derived the transfer function which characterizes the amplification of shear displacements by the layered system. Within the framework of problems on the oscillations of two- and five layered systems, the analytical studies were confirmed by numerical evaluations of transfer functions. In particular, using the built-in functions of the system «Mathematica», it is developed the numerical procedure for evaluating the frequency dependencies of amplification factor for layered Kelvin—Voigt media and media with oscillating inclusions. Moreover, for the two-layered system, it is analyzed the effect on the transfer function for the ratio of layers’ shear moduli and the ratio of the inclusions’ natural frequencies. It is also shown that the maxima in the transfer function correspond to the eigenfrequencies of the boundary value problem.The obtained results and the proposed approach to the study of the response of the layered inhomogeneous medium to vibrational perturbations can serve as a theoretical basis for earthquake-resistant design and construction.

scholarly journals Procedure of synthesising astatic digital tracking systems analytically from continuous prototypes

2017 ◽  
pp. 43-48
Author(s):  
T. A. Antonova ◽  
A. V. Semenov
Keyword(s):  
Transfer Function ◽  
Discrete System ◽  
Transfer Functions ◽  
Constant Error ◽  
Sampling Period ◽  
Discrete Systems ◽  
Synthesis Methods ◽  
Continuous Systems ◽  
Tracking Systems ◽  
Digital Tracking

The article deals with the problem of synthesising astatic digital tracking systems analytically, taking into account the requirements for astaticism quality and order; solving this problem leads to finding the desired transfer function of a discrete system based on a continuous prototype (a continuous transfer function). The advantage of the method specified above is that it makes it possible to eliminate the procedure bias caused by quantising desired transfer functions of continuous systems when synthesising astatic discrete systems. This bias is inherent in other synthesis methods that assume that reducing the sampling period will also lower the constant error. We used the MATLAB environment to develop our software implementing this method for automated construction of a desired transfer function of a discrete system

Analytic integration of contrast transfer functions

1988 ◽  
Vol 46 ◽  
pp. 822-823
Author(s):  
Peter Rez
Keyword(s):  
Wave Function ◽  
Transfer Function ◽  
Transfer Functions ◽  
Spherical Aberration ◽  
Continuous Distribution ◽  
Objective Lens ◽  
Direction Parallel ◽  
Scattering Angle ◽  
Analytic Integration ◽  
Image Position

In high resolution microscopy the image amplitude is given by the convolution of the specimen exit surface wave function and the microscope objective lens transfer function. This is usually done by multiplying the wave function and the transfer function in reciprocal space and integrating over the effective aperture. For very thin specimens the scattering can be represented by a weak phase object and the amplitude observed in the image plane is1where fe (Θ) is the electron scattering factor, r is a postition variable, Θ a scattering angle and x(Θ) the lens transfer function. x(Θ) is given by2where Cs is the objective lens spherical aberration coefficient, the wavelength, and f the defocus.We shall consider one dimensional scattering that might arise from a cross sectional specimen containing disordered planes of a heavy element stacked in a regular sequence among planes of lighter elements. In a direction parallel to the disordered planes there will be a continuous distribution of scattering angle.

Sign in / Sign up

Export Citation Format

Share Document