Analysis of fracture induced scattering of microseismic shear-waves     

Baban M. Yousef  Doug A. Angus 《Studia Geophysica et Geodaetica》2017,61(4):728-753

Fractures are pervasive features within the Earth’s crust and have a significant influence on the multi-physical response of the subsurface. The presence of coherent fracture sets often leads to observable seismic scattering enabling seismic techniques to remotely locate and characterise fracture systems. In this study, we confirm the general scale-dependence of seismic scattering and provide new results specific to shear-wave propagation. We do this by generating full waveform synthetics using finite-difference wave simulation within an isotropic background model containing explicit fractures. By considering a suite of fracture models having variable fracture density and fracture size, we examine the widening effect of wavelets due to scattering within a fractured medium by using several different approaches, such as root-mean-square envelope analysis, shear-wave polarisation distortion, differential attenuation analysis and peak frequency shifting. The analysis allows us to assess the scattering behavior of parametrised models in which the propagation direction is either normal or parallel to the fracture surfaces. The quantitative measures show strong observable deviations for fractures size on the order of or greater than the dominant seismic wavelength within the Mie and geometric scattering regime for both propagation normal and parallel to fracture strike. The results suggest that strong scattering is symptomatic of fractures having size on the same order of the probing seismic wave.  相似文献   

Application of different data-driven methods for the prediction of total dissolved solids in the Zarinehroud basin   总被引：3，自引：3，他引：0  

Sarvin Zaman Zad Ghavidel  Majid Montaseri 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(8):2101-2118

A total dissolved solid (TDS) is an important indicator for water quality assessment. Since the composition of mineral salts and discharge affects the TDS of water, it is important to understand the relationship of mineral salt composition with TDS. In the present study, four artificial intelligence approaches, namely artificial neural networks (ANNs), two different adaptive-neuro-fuzzy inference system (ANFIS) including ANFIS with grid partition (ANFIS-GP) and ANFIS with subtractive clustering (ANFIS-SC), and gene expression programming (GEP) were applied to forecast TDS in river water over a period of 18 years at seven different sites. Five different GEP, ANFIS and ANN models comprising various combinations of water quality and flow variables from Zarinehroud basin in northwest of Iran were developed to forecast TDS variations. The correlation coefficient (R), root mean square error and mean absolute error statistics were used for evaluating the accuracy of models. Based on the comparisons, it was found that the GEP, ANFIS-GP, ANFIS-SC and ANN models could be employed successfully in forecasting TDS variations. A comparison was made between these artificial intelligence approaches which emphasized the superiority of GEP over the other intelligent models.  相似文献   

Integrated Interpretation of Interwell Connectivity Using Injection and Production Fluctuations   总被引：1，自引：1，他引：0  

Ali A. Yousef  Jerry L. Jensen  Larry W. Lake 《Mathematical Geosciences》2009,41(1):81-102

A method to characterize reservoirs, based on matching temporal fluctuations in injection and production rates, has recently been developed. The method produces two coefficients for each injector–producer pair; one parameter, λ, quantifies the connectivity and the other, τ, quantifies the fluid storage in the vicinity of the pair. Previous analyses used λ and τ separately to infer the presence of transmissibility barriers and conduits in the reservoir, but several common conditions could not be easily distinguished. This paper describes how λ and τ can be jointly interpreted to enhance inference about preferential transmissibility trends and barriers. Two different combinations are useful: one is a plot of log (λ) versus log (τ) for a producer and nearby injectors, and the second is a Lorenz-style flow capacity (F) versus storativity (C) plot. These techniques were tested against the results of a numerical simulator and applied to data from the North Buck Draw field. Using the simulated data, we find that the F–C plots and the λ–τ plots are capable of identifying whether the connectivity of an injector–producer well pair is through fractures, a high-permeability layer, multiple-layers or through partially completed wells. Analysis of data from the North Buck Draw field shows a reasonable correspondence between τ and the tracer breakthrough times. Of two possible geological models for Buck Draw, the F–C and λ–τ plots support the model that has less connectivity in the field. The wells in fluvial deposits show better communication than those wells in more estuarine-dominated regions.  相似文献   

Geochemical and quality assessment of groundwater of Marand Basin, East Azarbaijan Province, northwestern Iran   总被引：2，自引：2，他引：0  

Kaveh Pazand  Ardeshir Hezarkhani  Yousef Ghanbari  Nasrin Aghavali 《Environmental Earth Sciences》2012,67(4):1131-1143

The chemical analysis of 83 water wells in the Marand area, Azarbaijan Province NW of Iran was evaluated to determine the hydrogeochemical processes and ion concentration background in the region. Over the entire area, the dominated hydrochemical types are Ca? +?Mg?+?SO₄?+?Cl, Ca?+?SO₄, Na?+?Cl and Ca?+?Mg?+?HCO₃. Based on the total hardness, the softness of the groundwater is determined. According to electrical conductivity (EC) and sodium adsorption ratio (SAR), the most dominant classes are C3?CS1, C3?CS2, C4?CS2 and C2?CS1. The major ion concentrations are below the acceptable level for drinking water. The groundwater salinity hazard is medium to high, but the Na hazard is low to medium; with regard to irrigation water, the quality is low to medium. So, a drainage system is necessary to avoid the increase of toxic salt concentrations.  相似文献   

Combining AHP with GIS for Predictive Cu Porphyry Potential Mapping: A Case Study in Ahar Area (NW,Iran)   总被引：1，自引：0，他引：1  

Kaveh Pazand  Ardeshir Hezarkhani  Mohammad Ataei  Yousef Ghanbari 《Natural Resources Research》2011,20(4):251-262

Using the analytic hierarchy process (AHP) method for multi-index evaluation has special advantages, while the use of geographic information systems (GIS) is suitable for spatial analysis. Combining AHP with GIS provides an effective approach for studies of mineral potential mapping evaluation. Selection of potential areas for exploration is a complex process in which many diverse criteria are to be considered. In this article, AHP and GIS are used for providing potential maps for Cu porphyry mineralization on the basis of criteria derived from geologic, geochemical, and geophysical, and remote sensing data including alteration and faults. Each criterion was evaluated with the aid of AHP and the result mapped by GIS. This approach allows the use of a mixture of quantitative and qualitative information for decision-making. The results of application in this article provide acceptable outcomes for copper porphyry exploration.  相似文献   

Structural Setting and Kinematic Analysis of the Halaban Region,Eastern Arabian Shield,Saudi Arabia     

Osama M. KASSEM  Yousef A. ALAMRI  Faisal K. ZAIDI  Abdel Aziz M. AL BASSAM  Mansour H. AL-HASHIM 《《地质学报》英文版》2021,95(3):750-760

The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twentysix samples.The kinematic vorticity number (W_m) for deformed rocks in the study area ranged from～0.6 to 0.9.The direction of the long axes for finite strain data (X axes) revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data (Z axes) were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.  相似文献   

North and south major flare periodicities during solar cycle 20     

A. A. Galal  Shahinaz Yousef  E. Bebars 《Astrophysics and Space Science》1995,228(1-2):19-30

The periodicities of monthly values of major flare numbers and comprehensive major flare index (CFI) have been studied for the 20^th solar cycle. It has been proved that the periodicity 152 days exists also in the southern (S) solar hemisphere. This periodicity has been previously defined in the earlier cycles to be a northern (N) periodicity, but it has migrated to the southern hemisphere (S) during the cycles 19, 20, 21. For the whole solar disk data, it has been found that the periodicity at 78.43^d is much remarkable than its first harmonic at 156.86^d. We have also detected very strong periodicity at 548.96^d in N-hemisphere while a strong one has been found near 100^d in both solar hemispheres. The detected periodicities at 80±2^d and 101-⁺1^d seems to have a global origin . The 87.1^d periodicity is present and it is suggested that it is related to 88^d periodicity attributed to the tidal influence of the planet Mercury on sunspots. Both hemispheres present their periodicities independently.  相似文献   

Impact of constitutive models on the numerical analysis of underground constructions   总被引：1，自引：0，他引：1  

Yousef Hejazi  Daniel Dias  Richard Kastner 《Acta Geotechnica》2008,3(4):251-258

The constitutive model frequently used in numerical calculations of tunnel excavation is linear-elastic perfectly plastic with a Mohr–Coulomb (MC) failure criterion. Generally, this leads to shallower and wider surface settlement troughs than those observed experimentally. It is therefore necessary to use adapted constitutive models for the design of underground works. In this paper, three constitutive models are implemented in a two-dimensional simulation of an underground excavation in plane strain: a linear-elastic perfectly plastic model (the MC model), an elastoplastic model with isotropic hardening [the hardening soil (HS) model, Schanz et al., Beyond 2000 in computational geotechnics, Balkema, Rotterdam, pp. 281–290, 1999] and an extension of this model which implies an evolution of the stiffness modulus in the small-strain range according to the strain level (the HS model with small-strain stiffness “HS-Small”, Benz, Small-strain stiffness of soils and its numerical consequences. Ph.D. thesis, Universitat Stuttgart, 189 pp., 2007). The study is based on the results of drained triaxial compression tests representing an overconsolidated clay (Gasparre, Advanced laboratory characterisation of London clay. Ph.D. thesis, Imperial College London, 598 pp., 2005); and is then applied to a shallow tunnel. The impact of the constitutive model is highlighted as well as the limits of the simplest constitutive model.  相似文献   

Statistical analysis of different chemical elements in groundwater of northwestern Saudi Arabia     

Taisser Zumlot  Awni Batayneh  Haider Zaman  Habes Ghrefat  Saad Mogren  Yousef Nazzal  Eslam Elawadi  Mahmoud Elwaheidi 《Journal of the Geological Society of India》2016,87(4):469-475

A total of 72 water samples were collected from the sub-surface aquifer system in the Midyan basin and analyzed for 24 major, minor and trace elements. Histograms and normal quantile plots were used to delineate the sub-populations of the chemical constituents in the studied groundwater samples. Some of the elements such as Al, K, Ca, Mg, Na and Cl have concentrations that could be linked to the weathering of the surface rock strata. On the other hand, the elements like As, Pb and Sb have concentration, that can be linked to agricultural practices in the area. The use of simple statistical analysis, frequency histograms, and Q-Q plots were useful for the detection and evaluation of elemental constituents in the groundwater of the study area.  相似文献   

Mapping groundwater potential field using catastrophe fuzzy membership functions and Jenks optimization method: a case study of Maragheh-Bonab plain,Iran     

Sina Sadeghfam  Yousef Hassanzadeh  Ata Allah Nadiri  Rahman Khatibi 《Environmental Earth Sciences》2016,75(7):545

  相似文献