Seismic Property Research Articles

Research Status and Prospects of Cable Domes

Advances in the research on cable domes were summarized and reviewed, such as structural improvements and innovation, prestressed mode and optimize designing of cable dome structure, dynamic and wind resistance performance analysis, construction technology, model experiment and sensitivity analysis. Some topics worthy further research were proposed, including seismic property study, improvement and innovation in construction techniques and methods, fire resistance study, stiffness analysis of structures, general design methods and software. This work will provide a meaningful reference for the design and application of cable domes.

The Primary Exploring of Seismic Property of Different Type Structure House

The article makes pushover analysis for two multiplayer frames(one common frame and one abnormity columniation frame)and three small high-rise structures (shearwall, short-climbed shearwall and frame-shearwall structure)based on software ADINA. Consequently, from displacement, vibration period and storey shear force, it is shown that the abnormity columniation frame can meet the seismic requirement and the short-climbed shearwall have better seismic capacity.

Joint geophysical and petrological models for the lithosphere structure of the Antarctic Peninsula continental margin

SUMMARY The Antarctic Peninsula (AP) is a composite magmatic arc terrane formed at the Pacific margin of Gondwana. Through the late Mesozoic and Cenozoic subduction has stopped progressively from southwest to northeast as a result of a series of ridge trench collisions. Subduction may be active today in the northern part of the AP adjacent to the South Shetland Islands. The subduction system is confined by the Shackleton and Hero fracture zones. The magmatic arc of the AP continental margin is marked by high-amplitude gravity and magnetic anomaly belts reaching highest amplitudes in the region of the South Shetland Islands and trench. The sources for these anomalies are highly magnetic and dense batholiths of mafic bulk composition, which were intruded in the Cretaceous, due to partial melting of upper-mantle and lower-crustal rocks. 2-D gravity and magnetic models provide new insights into crustal and upper-mantle structure of the active and passive margin segments of the northern AP. Our models incorporate seismic refraction constraints and physical property data. This enables us to better constrain both Moho geometry and petrological interpretations in the crust and upper mantle. Model along the DSS-12 profile crosses the AP margin near the Anvers Island and shows typical features of a passive continental margin. The second model along the DSS-17 profile extends from the Drake Passage through the South Shetland Trench/Islands system and Bransfield Strait to the AP and indicates an active continental margin linked to slow subduction and on-going continental rifting in the backarc region. Continental rifting beneath the Bransfield Strait is associated with an upward of hot upper mantle rocks and with extensive magmatic underplating.

Reservoir prediction using pre-stack inverted elastic parameters

This is a case study of the application of pre-stack inverted elastic parameters to tight-sand reservoir prediction. With the development of oil and gas exploration, pre-stack data and inversion results are increasingly used for production objectives. The pre-stack seismic property studies include not only amplitude verse offset (AVO) but also the characteristics of other elastic property changes. In this paper, we analyze the elastic property parameters characteristics of gas- and wet-sands using data from four gas-sand core types. We found that some special elastic property parameters or combinations can be used to identify gas sands from water saturated sand. Thus, we can do reservoir interpretation and description using different elastic property data from the pre-stack seismic inversion processing. The pre-stack inversion method is based on the simplified Aki-Richard linear equation. The initial model can be generated from well log data and seismic and geologic interpreted horizons in the study area. The input seismic data is angle gathers generated from the common reflection gathers used in pre-stack time or depth migration. The inversion results are elastic property parameters or their combinations. We use a field data example to examine which elastic property parameters or combinations of parameters can most easily discriminate gas sands from background geology and which are most sensitive to pore-fluid content. Comparing the inversion results to well data, we found that it is useful to predict gas reservoirs using λ, λρ, λ/µ, and K/µ properties, which indicate the gas characteristics in the study reservoir.

Impediments to Predicting Site Response: Seismic Property Estimation and Modeling Simplifications

Abstract We compare estimates of the empirical transfer function (ETF) to the plane SH -wave theoretical transfer function (TTF) within a laterally constant medium for invasive and noninvasive estimates of the seismic shear-wave slownesses at 13 Kiban-Kyoshin network stations throughout Japan. The difference between the ETF and either of the TTFs is substantially larger than the difference between the two TTFs computed from different estimates of the seismic properties. We show that the plane SH -wave TTF through a laterally homogeneous medium at vertical incidence inadequately models observed amplifications at most sites for both slowness estimates, obtained via downhole measurements and the spectral analysis of surface waves. Strategies to improve the predictions can be separated into two broad categories: improving the measurement of soil properties and improving the theory that maps the 1D soil profile onto spectral amplification. Using an example site where the 1D plane SH -wave formulation poorly predicts the ETF, we find a more satisfactory fit to the ETF by modeling the full wavefield and incorporating spatially correlated variability of the seismic properties. We conclude that our ability to model the observed site response transfer function is limited largely by the assumptions of the theoretical formulation rather than the uncertainty of the soil property estimates.

High-frequency Rayleigh-Wave method

High-frequency (≥2 Hz) Rayleigh-wave data acquired with a multichannel recording system have been utilized to determine shear (S)-wave velocities in near-surface geophysics since the early 1980s. This overview article discusses the main research results of high-frequency surface-wave techniques achieved by research groups at the Kansas Geological Survey and China University of Geosciences in the last 15 years. The multichannel analysis of surface wave (MASW) method is a non-invasive acoustic approach to estimate near-surface S-wave velocity. The differences between MASW results and direct borehole measurements are approximately 15% or less and random. Studies show that simultaneous inversion with higher modes and the fundamental mode can increase model resolution and an investigation depth. The other important seismic property, quality factor (Q), can also be estimated with the MASW method by inverting attenuation coefficients of Rayleigh waves. An inverted model (S-wave velocity or Q) obtained using a damped least-squares method can be assessed by an optimal damping vector in a vicinity of the inverted model determined by an objective function, which is the trace of a weighted sum of model-resolution and model-covariance matrices. Current developments include modeling high-frequency Rayleigh-waves in near-surface media, which builds a foundation for shallow seismic or Rayleigh-wave inversion in the time-offset domain; imaging dispersive energy with high resolution in the frequency-velocity domain and possibly with data in an arbitrary acquisition geometry, which opens a door for 3D surface-wave techniques; and successfully separating surface-wave modes, which provides a valuable tool to perform S-wave velocity profiling with high-horizontal resolution.

Study on seismic behaviour of a new hybrid structure with shaking table test and numerical analysis

AbstractThis paper presents a study on a hybrid high‐rise structure that has two structural systems: the main one is a mega‐frame consisted of mega‐columns, strengthened floors and the outrigger truss on the top; the secondary one consists of typical floors between the strengthened floors. Because of the complexity and innovation of the structural system, a detailed study, including shaking table test and numerical analysis, is needed to research the seismic property of the hybrid structure. First, a 1/50 shaking table model was tested by the State Key Laboratory for Disaster Reduction in Civil Engineering of Tongji University to obtain the frequencies of the free‐vibration modes and dynamic property of the model. Second, this paper used 3D finite element analysis software, named MIDAS, to build the numerical models. Two kinds of models were made to simulate the shaking table model and the prototype structure, respectively, and then a comparison between the analytical and experimental results was presented in this paper to verify the numerical models. In addition, the seismic behaviour of the prototype was analysed by the MIDAS. Finally, the structural system of the new hybrid structure was verified to be valid and applicable. Copyright © 2009 John Wiley & Sons, Ltd.

Modulus of Rubblized Portland Cement Concrete from Surface Wave Testing

Several Interstate portland cement concrete (PCC) pavement sections in New Jersey are being rubblized by multihead breaker equipment; the rubblized concrete is later compacted by several passes of vibratory Z-grid and rubber-wheel static rollers. To evaluate the modulus of the rubblized PCC and to compare it to the modulus of a typical dense graded aggregate base material, nondestructive evaluation using surface waves, implemented in a portable seismic property analyzer, was conducted. The elastic modulus is evaluated from the average velocity of surface waves, from the shortest measurable wavelength (about 2 in.) to one equal to an approximate thickness of the rubblized concrete (about 10 in.). In addition to the average velocity (modulus), the variation of the surface wave (phase) velocity with wavelength can be related to the variation of modulus with depth. The modulus obtained from seismic testing is a low-strain modulus, and appropriate corrections (reductions) should be provided to describe it as a resilient modulus. The modulus variation is largely constrained between 550 and 2,800 MPa (80 and 400 ksi), with an average modulus between 1,100 and 1,400 MPa (160 and 200 ksi). Significant modulus variation is attributed to the rubblization process, which provides the highest crushing of concrete near the surface; near the bottom, rubblized concrete appears more like fractured rock and can form an uneven interface between the two zones. In general, the modulus of rubblized PCC is higher than the modulus of a typical granular base.

3D geological modeling of dual porosity carbonate reservoirs: A case from the Kenkiyak pre-salt oilfield, Kazakhstan

Abstract The 3D geological model of dual porosity reservoirs in the Kenkiyak pre-salt oilfield is built step by step based on the detailed core observation, employing core data, log data, geological data, and seismic data. Firstly, the structural model is built. Then the sedimentary facies model is built on the basis of analyzing seismic facies and electro-facies, and the models of reservoir matrix properties controlled by the sedimentary facies are built based on structure analysis and methods optimization. Secondly, the fracture distribution model is established by applying the results of the seismic property analysis and the core fracture description. Thirdly, the three-dimensional integrated geological model of the dual porosity reservoirs is set up by combining the matrix property models with the fracture distribution model and applying the filtration theory between matrix and fractures. The set of methods finally provides a fracture distribution model, a fracture equivalent permeability model, and a dual porosity equivalent permeability model, which can be directly provided to reservoir engineers for numerical simulation.

Dynamic and seismic property experiments of high damping concrete and its frame models

The loss tangent and storage modulus of cement mortar containing treated silica fume and styrene-acrylic are measured. Shaking table tests on three groups of 1/4 models of high damping concrete frames are conducted to compare the effects of reducing vibration. A relationship between the viscosity coefficient of high damping concrete and the damping coefficient of structure is established by analyzing dynamic parameters like damping ratio and frequency, and comparing responses of relative displacement and absolute acceleration. Surface treatment of silica fume and styrene-acrylic emulsion prior to incorporation in a cement mortar increases the loss tangent of the resulting composite by 40–400% as compared to the cement mortar without any admixtures, and the damping ratio of the reinforced concrete is raised by 7%–9%. In addition, a theoretical method of determining the viscosity coefficient of the material on the basis of shaking table test results is put forward.

The seismic property of reef flat in the Changxing-Feixianguan Formation, Northwest Sichuan Province, China

The development of a carbonate reservoir is dominated by its primary sedimentary environment. Generally, a good reservoir must be the oolite of a bank or bioclastics of an organic reef in a marginal mesa, which must deposit on the slope of the mesa. Therefore, the analyses of sequence stratigraphy are the key for predicting the presence of carbonate reservoirs. A typical sequence pattern can be seen in the Puguang gas field. As an independent lithological body, the mechanical property of a reef flat is very different from the surrounding rock, causing stress to concentrate. Stress centralization will, in turn, cause a lot of fractures and faults to develop, and ultimately, result in a gas chimney, which is a seismic smear zone beneath or above the reef flat. Known gas fields, such as the puguang gas field, also possess gas chimneys. Sequence stratigraphy patterns in the marginal mesa and gas chimney near the reservoir are very obvious in all known fields in southeast and east Sichuan Province. By analyzing the seismic features of all known gas fields, a model to predict carbonate reservoirs has been set up. Using this prediction model, we have found that there is a typical reef flat of the marginal mesa in the Malubei structure of Tongnanba structural belts whose sequence stratigraphy pattern is very much like that of the Puguang gas field; and in the Cangxi-Jiulongshan structure, there is another reef flat which is symmetrical to the Malubei reef. The Cangxi reef flat possesses the largest platform edge shallow facies domestically found, and has a typical prograding sequence. Its gas chimney is very obvious too. Because the Cangxi reef flat is in the very vicinity of the hydrocarbon kitchen and the depression is much bigger than that of the Puguang gas fields, we predict that there may be a gigascopic gas field in Cangxi County. There may also be a large gas field in the Malubei structure.

Alluvial fan facies and their distribution in the Lower Talang Acar Formation, Northeast Betara Oilfield, Indonesia

This paper studies the alluvial fan facies characteristics and distribution in the Lower Talang Acar Formation in the Northeast Betara Oilfield. The conglomerate sedimentary characteristics and its distribution were studied based on core data, logging interpretation and seismic property analysis. The research indicated that alluvial fan deposits of Bed F in the Lower Talang Akar Formation were characterized by coarse granularity, poor sorting and low quality. Sand-bodies accumulate longitudinally, and inter-layers are poorly developed, extending locally in the transverse orientation. Typical logging response of alluvial fan system is summarized, and conglomerate is characterized by low gamma-ray (GR) intensity, low resistance, high density and low value between DLD and LLD, which reflects poor physical reservoir properties, coarse rocks and relatively high density. Conglomerate is developed mainly in the northeast and middle-south of the studied area. The upper part of bed F is found in a small area in the middle-south, while the lower part of bed F is developed in a relatively large area in the middle-south.

Stripping Detection in Asphalt Pavements with Seismic Methods

Stripping of hot-mix asphalt pavements has been a significant problem for many transportation agencies. The detection of stripping has been carried out by using either visual observation or laboratory strength tests of cores retrieved from the field. Ground-penetrating radar also has been used for this purpose. Seismic methods are presented here as a nondestructive tool to detect the extent of stripping. Seismic tests are beneficial because they are rapid to perform and nondestructive and because the material is tested in its natural state. The portable seismic property analyzer (PSPA) is an example of a device that uses two methods of analysis to detect stripping: ultrasonic surface wave (USW) and impact echo (IE). PSPA results and field cores retrieved (ground-truth data) from two sites were compared. PSPA, with the standard receiver spacing of 6 in., correlated well with cores when they were located in the first 10 in. of the asphalt layer (shallow). For deeper stripping, longer spacing between the receivers should be used. From the two methods of analysis, the USW method was found to be more effective than the IE in visualizing the extent and depth of low-quality layers in terms of asphalt stiffness.

Seafloor reflectivity—An important seismic property for interpreting fluid/gas expulsion geology and the presence of gas hydrate

A bottom-simulating reflection (BSR) is a seismic reflectivity phenomenon that is widely accepted as indicating the base of the gas-hydrate stability zone. The acoustic impedance difference between sediments invaded with gas hydrate above the BSR and sediments without gas hydrate, but commonly with free gas below, are accepted as the conditions that create this reflection. The relationship between BSRs and marine gas hydrate has become so well known since the 1970s that investigators, when asked to define the most important seismic attribute of marine gas-hydrate systems, usually reply, “a BSR event.” Research conducted over the last decade has focused on calibrating seafloor seismic reflectivity across the geology of the northern Gulf of Mexico (GoM) continental slope surface to the seafloor. This research indicates that the presence and character of seafloor bright spots (SBS) can be indicators of gas hydrates in surface and near-surface sediments (Figure 1). It has become apparent that SBSs on the cont...

Application of spectral decomposition to detection of dispersion anomalies associated with gas saturation

For many years geophysicists have attempted to exploit attenuation measurements in exploration seismology, because attenuation is perhaps the seismic property most closely related to the saturating fluid. The routine application of such ideas has proven elusive, however, largely because of the difficulty experienced when we attempt to measure attenuation in reflection data. Recent developments in the application of spectral decomposition methods to seismic data have opened the possibility of making further progress in this direction.

三次元地震探査を用いた油ガス層特性予測の現状と問題点

This document seeks to review and summarize issues about 3D seismic reservoir characterization and current technology trends for overcoming such issues. We list major difficulties in quantitative reservoir property estimation from 3D seismic data as i) poor understanding about the relationship between seismic attributes and reservoir properties, ii) the scale difference between seismic data and target geological model, and iii) integration of qualitative geological understanding into quantitative modeling framework. We then introduce several key efforts in two field examples for resolving them through integrated modeling. In the first example in a carbonate reservoir, rock physics study led to physical understanding of the identified correlation between Vp/Vs ratio and the absolute permeability, as well as AI(Acoustic Impedance) and porosity. We subsequently conducted porosity and permeability modeling using these relations, including a vertical downscaling step by the Gaussian Simulation with Locally Varying Mean method, which accomplished the final model consistent with well and seismic data. In the second example in a deep sea sandstone reservoir, non-unique relationship between seismic attributes, AI and EI(Elastic Impedance), and reservoir properties(lithology and pore fluid type) was quantified through statistical expression using PDFs(probability density functions) derived from well log data. The PDFs were used for interpreting seismically derived AI and EI to provide most-likely facies/fluid distribution. Finally, we present an example of applying multiple-point geostatistics for integrating seismically derived facies probability and prior geological information about the facies distribution. These field examples lead us to a conclusion that seismic reservoir property estimation methodology should be defined after careful consideration of the geological and geophysical background of the target fields, as well as the quality, quantity, and density of available data.

In-Place Determination of Stiffness of Subsurface Reclaimed Layers in Thin Surface Hot-Mix Asphalt Pavements: Fast Nondestructive Test and Analysis Method

Seismic testing and analysis using a nondestructive method was developed to determine the moduli of reclaimed layers in thin surface hot-mix asphalt pavements. This method is particularly useful when accurate backcalculation of moduli is difficult because of the existence of unknown layers and when the extraction of intact cores for laboratory testing is impossible. Sixteen Maine Department of Transportation projects with foamed asphalt and plant-mixed recycled asphalt pavement reclaimed layers were tested according to this method using a portable seismic property analyzer. Layer thickness uniformity was checked with a ground-penetrating radar, and falling weight deflectometer was used at multiple load levels to acquire deflection data. Seismic test data were analyzed to estimate layer moduli. The collected data were found to have very low variability. The deflections calculated with the predicted moduli and actual deflections were found to compare well, and the use of predicted moduli as seed moduli resulted in backcalculations with relatively low root-mean-square errors. The moduli were corrected for temperature, and design moduli were recommended. This newly developed method can be used effectively to determine the moduli of subsurface layers, and its use is important for collecting a large amount of data, specifically because of the highly variable nature of the reclaimed layers. A logical next step will be to develop artificial neural networks to automate the process of data reduction from seismic testing. This would allow departments of transportation and industry to fully use the benefits of this fast, nondestructive testing method.

Seismic Testing to Determine Quality of Hot-Mix Asphalt

Existing practices for acceptance of hot-mix asphalt are based on parameters such as adequate density, adequate thickness, and adequate air voids of the placed and compacted materials. Current mechanistic routines for structural design of flexible pavements consider mainly the modulus of each layer. Therefore, a procedure to measure the modulus of each pavement layer shortly after placement is highly desired. Laboratory tests on specimens prepared from material retrieved during construction, such as the simple-performance tests, can be used to determine these moduli. However, these methods are time-consuming, and the equipment costs are high. In addition, prepared specimens may not be representative of as-placed materials. Seismic tests are more practical because they are rapid to perform and are nondestructive, immediate results are obtained, and the material is tested in its natural state. The portable seismic property analyzer (PSPA) is an example of such a device. The PSPA is presented as a real-time nondestructive method with which to assess the hot-mix asphalt quality in the field.

In-Place Determination of Stiffness of Subsurface Reclaimed Layers in Thin Surface Hot-Mix Asphalt Pavements

Seismic testing and analysis using a nondestructive method was developed to determine the moduli of reclaimed layers in thin surface hot-mix asphalt pavements. This method is particularly useful when accurate backcalculation of moduli is difficult because of the existence of unknown layers and when the extraction of intact cores for laboratory testing is impossible. Sixteen Maine Department of Transportation projects with foamed asphalt and plant-mixed recycled asphalt pavement reclaimed layers were tested according to this method using a portable seismic property analyzer. Layer thickness uniformity was checked with a ground-penetrating radar, and falling weight deflectometer was used at multiple load levels to acquire deflection data. Seismic test data were analyzed to estimate layer moduli. The collected data were found to have very low variability. The deflections calculated with the predicted moduli and actual deflections were found to compare well, and the use of predicted moduli as seed moduli resulted in backcalculations with relatively low root-mean-square errors. The moduli were corrected for temperature, and design moduli were recommended. This newly developed method can be used effectively to determine the moduli of subsurface layers, and its use is important for collecting a large amount of data, specifically because of the highly variable nature of the reclaimed layers. A logical next step will be to develop artificial neural networks to automate the process of data reduction from seismic testing. This would allow departments of transportation and industry to fully use the benefits of this fast, nondestructive testing method.

Seismic Testing to Determine Quality of Hot-Mix Asphalt

Existing practices for acceptance of hot-mix asphalt are based on parameters such as adequate density, adequate thickness, and adequate air voids of the placed and compacted materials. Current mechanistic routines for structural design of flexible pavements consider mainly the modulus of each layer. Therefore, a procedure to measure the modulus of each pavement layer shortly after placement is highly desired. Laboratory tests on specimens prepared from material retrieved during construction, such as the simple-performance tests, can be used to determine these moduli. However, these methods are time-consuming, and the equipment costs are high. In addition, prepared specimens may not be representative of as-placed materials. Seismic tests are more practical because they are rapid to perform and are nondestructive, immediate results are obtained, and the material is tested in its natural state. The portable seismic property analyzer (PSPA) is an example of such a device. The PSPA is presented as a real-time ...