Boron contamination in groundwater at a sewage waste disposal facility near Jeddah,Saudi Arabia     

Faisal Rehman  Tariq Cheema 《Environmental Earth Sciences》2017,76(5):218

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Offshore Carbonate Facies Characterization and Reservoir Quality of Miocene Rocks in the Southern Margin of South China Sea     

Hammad Tariq JANJUHAH  Abubaker ALANSARI 《《地质学报》英文版》2020,94(5):1547-1561

Carbonate rocks are important hydrocarbon reservoirs around the globe and in Southeast Asia a key one, particularly, is the Central Luconia province. Understanding the internal characteristics, distribution, geometry and lateral extent of these rocks is essential for exploration and production success. Detailed work on Miocene carbonate reservoir facies, north of Bintulu, offshore Sarawak includes qualitative and quantitative analysis of photomicrographs and reservoir quality, considering especially microporosity. Stratigraphically, these carbonates are known as Cycles IV and V and are represented by eight major facies types (F-1 to F-8]. They comprise: coated grain packstone (F-1) (av. ? = 3%, av. Kh = 0.5 mD) (av = Average; ? = total porosity, and Kh = permeability); massive coral lime grainstone (F-2) (av. ? = 14.7%, av. Kh = 6 mD); oncolite lime grain-dominated packstone (F-3) (av. ? = 10%, av. Kh = 4 mD); skeletal lime/dolo-packstone (F-4) (av. ? = 15%, av. Kh = 4.6 mD); coral (platy) lime mud-dominated packstone (F-5) (av. ? = 4%, av. Kh = 0.5 mD); coral (branching) lime-dominated pack-grainstone (F-6) (av. ? = 15%, av. Kh = 1 mD); cross-bedded skeletal lime packstone (F-7) (av. ? = 20%, av. Kh = 2 mD); and bioturbated carbonate mudstone/chalk (F-8) (av. ? = 8%, av. Kh = 0.8 mD). Study of thin sections reveals that red algae, foraminifera, and corals are the dominant fossil components with a minor admixture of skeletal fragments of echinoderms, bivalves, bryozoans, and green algae. All parameters, e.g., facies characterization, petrography, porosity–permeability value, and microporosity value were utilized to obtain a reliable reservoir quality. The microporosity value was quantified using digital image analysis software and is significant for recognition of good reservoir quality. Consideration of the presence of microporosity against the total porosity in the carbonate rocks has improved the correlation coefficient (R2) value, which has increased from 0.51 to 0.82.  相似文献   

Pure P- and S-wave equations in transversely isotropic media     

Alexey Stovas  Tariq Alkhalifah  Umair bin Waheed 《Geophysical Prospecting》2020,68(9):2762-2769

Pure-mode wave propagation is important for applications ranging from imaging to avoiding parameter tradeoff in waveform inversion. Although seismic anisotropy is an elastic phenomenon, pseudo-acoustic approximations are routinely used to avoid the high computational cost and difficulty in decoupling wave modes to obtain interpretable seismic images. However, such approximations may result in inaccuracies in characterizing anisotropic wave propagation. We propose new pure-mode equations for P- and S-waves resulting in an artefact-free solution in transversely isotropic medium with a vertical symmetry axis. Our approximations are more accurate than other known approximations as they are not based on weak anisotropy assumptions. Therefore, the S-wave approximation can reproduce the group velocity triplications in strongly anisotropic media. The proposed approximations can be used for accurate modelling and imaging of pure P- and S-waves in transversely isotropic media.  相似文献   

Traffic ‐and Industry‐Related Air Pollution Exposure Assessment in an Asian Megacity          下载免费PDF全文

Muhammad Usman Alvi  Farrukh Chishtie  Imran Shahid  Tariq Mahmud  Riaz Hussain 《洁净——土壤、空气、水》2018,46(1)

Like other Asian countries, Pakistan is facing the issue of air pollution due to rapid urbanization, enormous transportation increases, and other related human activities. Moreover, continuously increasing emission sources have not only raised pollutant concentrations but also their types, thus damaging both human health and the environment. Faisalabad is the third largest megacity of Pakistan and its state of air quality is getting worse due to factors such as industrialization, high traffic volumes, and extensive fossil‐fuel‐burning activities. This review article aims to highlight the present status of air pollution in this city with special reference to particulate matter, elemental profiles, gaseous pollutants, organic–inorganic particulate contents as well as their sources. The concentration levels of these entities were also compared with other national and international cities, and related environmental standards. It is found that current levels of these pollutants are beyond safety limits as specified by various environment protection agencies and organizations. Several weak aspects and gaps are also identified along with suggestions for improvements of the present situation and directions for future research.  相似文献   

Study on the full-waveform inversion strategy for 3D elastic orthorhombic anisotropic media: application to ocean bottom cable data     

Ju-Won Oh  Tariq Alkhalifah 《Geophysical Prospecting》2019,67(5):1219-1242

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P-wave complex-valued traveltimes in homogeneous attenuating transversely isotropic media     

Qi Hao  Umair bin Waheed  Tariq Alkhalifah 《Geophysical Prospecting》2019,67(9):2402-2413

Computation of complex-valued traveltimes provides an efficient approach to describe the seismic wave attenuation for applications like attenuation tomography, inverse Q filtering and Kirchhoff migration with absorption compensation. Attenuating acoustic transverse isotropy can be used to describe the directional variation of velocity and attenuation of P-waves in thin-bedding geological structures. We present an approximate method to solve the acoustic eikonal equation for an attenuating transversely isotropic medium with a vertical symmetry axis. We take into account two similar parameterizations of an attenuating vertical symmetry axis medium. The first parameterization uses the normal moveout velocity, whereas the second parameterization uses the horizontal velocity. For each parameterization, we combine perturbation theory and the Shanks transform in different ways to derive analytic solutions. Numerical examples show that the analytic solutions derived from the second parameterization yield better accuracy. The Shanks transform solution with respect to only the anellipticity parameter from the second parameterization is demonstrated numerically to be the most accurate among all the analytic solutions.  相似文献   

Scanning anisotropy parameters in horizontal transversely isotropic media          下载免费PDF全文

Nabil Masmoudi  Alexey Stovas  Tariq Alkhalifah 《Geophysical Prospecting》2017,65(4):981-991

The horizontal transversely isotropic model, with arbitrary symmetry axis orientation, is the simplest effective representative that explains the azimuthal behaviour of seismic data. Estimating the anisotropy parameters of this model is important in reservoir characterisation, specifically in terms of fracture delineation. We propose a travel‐time‐based approach to estimate the anellipticity parameter η and the symmetry axis azimuth ? of a horizontal transversely isotropic medium, given an inhomogeneous elliptic background model (which might be obtained from velocity analysis and well velocities). This is accomplished through a Taylor's series expansion of the travel‐time solution (of the eikonal equation) as a function of parameter η and azimuth angle ?. The accuracy of the travel time expansion is enhanced by the use of Shanks transform. This results in an accurate approximation of the solution of the non‐linear eikonal equation and provides a mechanism to scan simultaneously for the best fitting effective parameters η and ?, without the need for repetitive modelling of travel times. The analysis of the travel time sensitivity to parameters η and ? reveals that travel times are more sensitive to η than to the symmetry axis azimuth ?. Thus, η is better constrained from travel times than the azimuth. Moreover, the two‐parameter scan in the homogeneous case shows that errors in the background model affect the estimation of η and ? differently. While a gradual increase in errors in the background model leads to increasing errors in η, inaccuracies in ?, on the other hand, depend on the background model errors. We also propose a layer‐stripping method valid for a stack of arbitrary oriented symmetry axis horizontal transversely isotropic layers to convert the effective parameters to the interval layer values.  相似文献   

A Spatially Periodic Solute Boundary for MT3DMS and PHT3D          下载免费PDF全文

Tariq Laattoe  Vincent E. A. Post  Adrian D. Werner 《Ground water》2017,55(3):419-427

The assumption of spatial repetition is commonly made when producing bedform scale models of the hyporheic zone. Two popular solute transport codes, MT3DMS and PHT3D, do not currently provide the necessary boundary condition required to simulate spatial periodicity in hyporheic zone transport problems. In this study, we develop a spatially periodic boundary (SPB) for solutes that is compatible with a SPB that was previously developed for MODFLOW to simulate the flow component of spatially periodic problems. The approach is ideal for simulating groundwater flow and transport patterns under repeating surface features, such as ripples or dunes on the bottom of a lake or stream. The appropriate block‐centered finite‐difference approach to implement the boundary is presented and the necessary source code modifications are discussed. The performance of the solute SPB, operating in conjunction with the groundwater flow SPB, is explored through comparison of a multi‐bedform hyporheic‐zone model with a single bedform variant. The new boundary conditions perform well in situations where both dispersive effects and lateral seepage flux in the underflow regime beneath the hyporheic zone are minimal.  相似文献   

A comparison of IBC with 1997 UBC for modal response spectrum analysis in standard-occupancy buildings     

Tariq M. Nahhas 《地震工程与工程振动(英文版)》2011,10(1):99-113

This paper presents a comparison of the seismic forces generated from a Modal Response Spectrum Analysis (MRSA) by applying the provisions of two building codes, the 1997 Uniform Building Code (UBC) and the 2000-2009 International Building Code (IBC), to the most common ordinary residential buildings of standard occupancy. Considering IBC as the state of the art benchmark code, the primary concern is the safety of buildings designed using the UBC as compared to those designed using the IBC. A sample of four buildings with different layouts and heights was used for this comparison. Each of these buildings was assumed to be located at four different geographical sample locations arbitrarily selected to represent various earthquake zones on a seismic map of the USA, and was subjected to code-compliant response spectrum analyses for all sample locations and for five different soil types at each location. Response spectrum analysis was performed using the ETABS software package. For all the cases investigated, the UBC was found to be significantly more conservative than the IBC. The UBC design response spectra have higher spectral accelerations, and as a result, the response spectrum analysis provided a much higher base shear and moment in the structural members as compared to the IBC. The conclusion is that ordinary office and residential buildings designed using UBC 1997 are considered to be overdesigned, and therefore they are quite safe even according to the IBC provisions.  相似文献   

Wavefield dependency on virtual shifts in the source location     

Tariq Alkhalifah 《Geophysical Prospecting》2011,59(4):627-634

The wavefield dependence on a virtual shift in the source location can provide information helpful in velocity estimation and interpolation. However, the second‐order partial differential equation (PDE) that relates changes in the wavefield form (or shape) to lateral perturbations in the source location depends explicitly on lateral derivatives of the velocity field. For velocity models that include lateral velocity discontinuities this is problematic as such derivatives in their classical definition do not exist. As a result, I derive perturbation partial differential wave equations that are independent of direct velocity derivatives and thus, provide possibilities for wavefield shape extrapolation in complex media. These PDEs have the same structure as the wave equation with a source function that depends on the background (original source) wavefield. The solutions of the perturbation equations provide the coefficients of a Taylor's series type expansion for the wavefield. The new formulas introduce changes to the background wavefield only in the presence of lateral velocity variation or in general terms velocity variations in the perturbation direction. The accuracy of the representation, as demonstrated on the Marmousi model, is generally good.  相似文献