Seismic modelling for reservoir studies: a comparison between convolutional and full-waveform methods for a deep-water turbidite sandstone reservoir     

Hamed Amini  Colin MacBeth  Asghar Shams 《Geophysical Prospecting》2020,68(5):1540-1553

Two seismic modelling approaches, that is, two-dimensional pre-stack elastic finite-difference and one-dimensional convolution methods, are compared in a modelling exercise over the fluid-flow simulation model of a producing deep-water turbidite sandstone reservoir in the West of Shetland Basin. If the appropriate parameterization for one-dimensional convolution is used, the differences in three-dimensional and four-dimensional seismic responses from the two methods are negligible. The key parameters to ensure an accurate seismic response are a representative wavelet, the distribution of common-depth points and their associated angles of incidence. Conventional seismic images generated by the one-dimensional convolutional model suffer from lack of continuity because it only accounts for vertical resolution. After application of a lateral resolution function, the convolutional and finite-difference seismic images are very similar. Although transmission effects, internal multiples and P-to-S conversions are not included in our convolutional modelling, the subtle differences between images from the two methods indicates that such effects are of secondary nature in our study. A quantitative comparison of the (normalized root-mean-square) amplitude attributes and waveform kinematics indicates that the finite-difference approach does not offer any tangible benefit in our target-oriented seismic modelling case study, and the potential errors from one-dimensional convolution modelling are comparatively much smaller than the production-induced time-lapse changes.  相似文献   

Radish (Raphanus sativus L.) Cultivar‐Specific Response to O3: Patterns of Biochemical and Plant Growth Characteristics          下载免费PDF全文

Ibrahim A. Hassan  Nigel B. Bell  Mike R. Ashmore  Lorenzo Cotrozzi  Nesreen S. Haiba  Jalal M. Basahi  Ahmad Summan  Talal Almeelbi  Iqbal M. Ismail 《洁净——土壤、空气、水》2018,46(6)

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Assessing Submerged Vegetation Roughness in Streambed under Clear Water Condition Using Physical Modeling     

Hosna Shafaei  Amini  Ata  Shirdeli  Azim 《Water Resources》2019,46(3):377-383

Water Resources - Roughness coefficient, also called Manning’s coefficient, is one of the most important hydraulic parameters in the rivers. This coefficient, in addition to the flow...  相似文献   

The effects of uniform and nonuniform pile spacing variations on local scour at pile groups     

Ata Amini  Nina Solaimani 《Marine Georesources & Geotechnology》2018,36(7):861-866

Pile groups are frequently used to support bridge decks. Scour in the vicinity of piles is the main cause for the bridges failure. In this research, to address the effects of uniform and nonuniform pile spacing on the equilibrium scour depth, laboratory experiments were carried out under steady clear-water conditions. For this purpose, scour depth produced by pile group with various pile spacing and arrangement was investigated using a laboratory flume. Flume bed was covered by uniform sediments with a median size of 0.9?mm and 0.2?m thickness. Flow discharge and velocity as well as scour depth were recorded in each experiment and the data were analyzed. The results showed that the pile spacing influences the local scour depth and with increase in uniform and transverse (perpendicular to the flow) spacing, the maximum scour depth was reduced. The pile spacing variation in line with the flow has a minor effect on scour depth. In addition, the pile spacing perpendicular to the flow was with the most influences on scour depth. The results of this research can be used by engineers to optimize the design of bridges.  相似文献   

Effect of time on dynamic properties of cohesive soils using improved transfer function estimators     

F. Amini   《Soil Dynamics and Earthquake Engineering》1999,18(6):192

Improved estimators of the transfer function (H2, H3, H4), in addition to the conventional estimator (H1), were used to evaluate the dynamic soil properties and to study the effect of confinement duration on damping and shear modulus of soils. In this study, two types of cohesive soils, a kaolinite and a bentonite, were tested using a resonant column apparatus under random torsional excitation conditions. Root meam square strain levels in the range of 10⁻³–10⁻² and confining pressures in the range of 34.47–150 kPa were considered. The confinement duration ranged from 500 to 20 000 min. The results of this study indicate that as time increases, the difference in damping values obtained by the various estimators of the transfer function decreases, whereas the shear moduli are not influenced by the variation in confinement duration.  相似文献   

On the number of required response history analyses     

Jalal Kiani  Charles Camp  Shahram Pezeshk 《Bulletin of Earthquake Engineering》2018,16(11):5195-5226

This study investigates the number of real ground motions (GMs) required to accurately capture the structural responses when using code-, intensity-, and risk-based seismic assessment frameworks. A key consideration is the use of as-recorded hazard consistent GMs, which appropriately characterize the seismic hazard of the site, for performing response history analysis. A comparison of the structural responses of 3 steel moment resisting buildings using different sets of GMs is made with results obtained using a large set of GMs. The empirical results demonstrate that, in most cases, a risk-based assessment needs a larger number of response history analyses than an intensity-based assessment method to accurately capture the seismic demand on the structural systems. Also, given the same number of GMs, the structural responses from a risk-based assessment are more reliable and stable than those for an intensity-based method. Moreover, the results help to quantify the uncertainty in the structural responses due to using different sample sets of GMs given the applied number of GMs. In addition, the results indicate that a significant bias in structural responses is likely when following the recommendations from several seismic design codes, which suggest utilizing the maximum structural responses if 3 GM pairs are used for response history analysis. A detailed statistical analyses show that the application of 7 GM pairs are sufficient to accurately and reliably estimate structural responses.  相似文献   

Zircon dating,Sr and Nd isotopes,and element geochemistry of the Khalifan pluton,NW Iran: Evidence for Variscan magmatism in a supposedly Cimmerian superterrane     

Fernando Bea  Ali Mazhari  Pilar Montero  Sadraldin Amini  Jalil Ghalamghash 《Journal of Asian Earth Sciences》2011,40(1):172-179

The Khalifan pluton of the Sanandaj-Sirjan Zone is composed of A-type peraluminous leucogranites with Nd model ages around 1.2 Ga. It intrudes an unfossiliferous sedimentary sequence previously considered as Cretaceous by analogy with neighboring areas. However, zircon U–Pb SHRIMP and Pb–Pb sequential evaporation dating have revealed that Khalifan granites are Carboniferous, with a precise age of 315 ± 2 Ma. This is the first reliable Variscan age obtained so far in this area, but there are geological indicators that other small plutonic bodies might also be Variscan. The existence of Carboniferous granite rocks in the Sanandaj-Sirjan Zone casts doubts on whether it was a part of the Cimmerian superterrane detached from east Gondwanide terranes because these characteristically lack Variscan magmatism. The age, chemical features and Nd isotopes of Khalifan granites are similar to those of the southernmost Urals and Tien Shan, so that we tentatively suggest that this area bears a Middle Asian instead of Cimmerian linkage.  相似文献   

Petrogenesis of granitic unit of Naqadeh complex, Sanandaj–Sirjan Zone, NW Iran     

Seyed Ali Mazhari  Sadraldin Amini  Jalil Ghalamghash  Fernando Bea 《Arabian Journal of Geosciences》2011,4(1-2):59-67

The granitic unit is a component of the Naqadeh plutonic complex, NW of Sanandaj–Sirjan Zone (NW Iran). This unit is composed of high-K calc-alkaline, slightly peraluminous (ASI?=?1.12–1.17) evolved monzogranites. These monzogranites have 41.85?±?0.81 Ma (zircon U–Pb sensitive, high-resolution ion microprobe (SHRIMP) age) with two inherited zircon ages of 98.5?±?1.7 and 586.6?±?13.1 Ma, respectively. The only enclave type consists of quartz-amphibolite enclaves indicating residual parental rocks. Chemical and isotopic (⁸⁷Sr/⁸⁶Sr_40Ma?=?0.708638; εNd_40Ma?=??4.26) characteristics of monzogranites suggest that they could be derived by partial melting of crustal mafic rocks followed by some assimilation of metasedimentary rocks. With regards to inherited zircon age and quartz-amphibolite composition of Naqadeh granite, the old mafic rocks of this complex (Naqadeh dioritic rocks with ~100 Ma) can be considered as parental rocks, and their partial melting under high water content, and assimilation of produced melt by metasedimentary rocks, would lead to the generation of a Naqadeh granitic unit.  相似文献   

Stability Analysis of Rock Slopes Against Block-Flexure Toppling Failure     

Mehdi Amini  Abbas Majdi  Mohammad Amin Veshadi 《Rock Mechanics and Rock Engineering》2012,45(4):519-532

Block-flexure is the most common type of toppling failure in rock slopes. In this case, some rock blocks fail due to tensile bending stresses and some overturn under their own weights. In this paper, first, a literature review of toppling failures is summarized. Then, a theoretical model is proposed for rock slopes with a potential for block-flexure toppling instability. Next, a new analytical approach is presented for the stability analysis of such slopes. Finally, a special computer code is developed for a quick stability assessment of the failures based on the proposed method. This code receives the rock slope parameters from the user as the input data and predicts its stability, along with the corresponding factor of safety against the failure, as the output. In addition, two case studies are used for practical verification of the proposed approach and the corresponding computer code as well.  相似文献   

Slope Stability Analysis of Earthen Levee Strengthened by High Performance Turf Reinforcement Mat under Hurricane Overtopping Flow Conditions   总被引：1，自引：0，他引：1  

Yingzi Xu  Lin Li  Farshad Amini 《Geotechnical and Geological Engineering》2012,30(4):893-905

The slope stability of levees during hurricane overtopping conditions involving storm surge and wind generated wave action is an important aspect to assess the safety of earthen levees. A comprehensive slope stability investigation was conducted in this study for an earthen levee subjected to full-scale overtopping scenarios, including storm surge only overflow, wave only overtopping, and combined wave and surge overtopping conditions. The crest and the landside of the levee were strengthened by high performance turf reinforcement mat (HPTRM) to protect against overtopping erosion. A conceptual model for HPTRM strengthened levee as well as a methodology for analysis and incorporation of various overtopping flow conditions in levee slope stability is presented. The findings of this study indicate that HPTRM strengthening of the levee improves the stability of the levee significantly during wave only as well as combined storm surge and wave overtopping conditions. However, during the storm surge conditions, the factor of safety is only improved slightly as a result of strengthening of the levee by HPTRM.  相似文献