Hydrogeochemical processes in a shallow coastal plain sand aquifer and tidal river systems (Calabar,Southeastern Nigeria): tracking wastewater and seawater pollution in ground and river waters   总被引：2，自引：2，他引：0  

A. E. Edet  R. H. Worden  E. A. Mohammed  M. R. Preston 《Environmental Earth Sciences》2012,65(7):1933-1953

  相似文献   

Drought analysis in Jordan under current and future climates   总被引：2，自引：0，他引：2  

Mohammed I. Al-Qinna  Nezar A. Hammouri  Mutewekil M. Obeidat  Fayez Y. Ahmad 《Climatic change》2011,106(3):421-440

Droughts have adverse socioeconomic, agricultural, and environmental impacts that can be reduced by assessing and forecasting drought behavior. The paper presents detailed analyses of both meteorological and vegetative droughts over the period from 1970 to 2005. Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) have been used to quantify drought according to severity, magnitude and spatial distribution at the Hashemite Kingdom of Jordan. Results suggest that the country faced during the past 35 years frequent non-uniform drought periods in an irregular repetitive manner. Drought severity, magnitudes and life span increased with time from normal to extreme levels especially at last decade reaching magnitudes of more than 4. Generated NDVI maps spatial analyses estimate crop-area percentage damage due to severe and extremely severe drought events occurred during October, December, and February of 2000 to be about 10%, 45%, and 30%, respectively. In response to drought spatial extent, the paper suggest the presence of two drought types, local drought acting on one or more geographical climatic parts and national drought, of less common but more severe, that extend over the whole country. Droughts in Jordan act intensively during January, February and March and tend to shift position with time by alternative migrations from southern desert parts to northern desert parts and from the eastern desert parts to highlands and Jordan Rift Valley (JRV) at the west. The paper also investigates the potential use of Global Climate Model’s (GCM) to forecast future drought events from 2010 till 2040. Tukey HSD test indicates that ECHAM5OM GCM is capable to predicted rainfall variation at the country and suggests future droughts to become more intensive at the northern and southern desserts with 15% rainfall reduction factor, followed by 10% reduction at the JRV, and 5% at the highlands.  相似文献   

Geological and geophysical exploration of the groundwater aquifers of As Suqah area, Makkah district, Western Arabian Shield, Saudi Arabia     

Mohammed Amin M. Sharaf 《Arabian Journal of Geosciences》2011,4(5-6):993-1004

As Suqah area is a NW–SE trending wadi present in the west central part of the Arabian Shield. It comprises Precambrian–Cambrian basement rocks, Cretaceous–Tertiary sedimentary succession, Tertiary–Quaternary basaltic lava flows, and Quaternary–Recent alluvial deposits. The magnetic anomalies indicated the presence of many recent local buried faults. These affected the distribution of the clastic sedimentary succession and seem to have controlled the deep groundwater aquifers. Groundwater movement is towards the west and northwest, following in general the surface drainage system. Hydraulic gradient varies greatly from one point to another depending on the pumping rates and cross-sectional area of the aquifer in addition to its transmissivity. The detailed results of the resistivity and seismic measurements were integrated with those obtained from test holes drilled in the study area. Groundwater occurs mainly in two water-bearing horizons, the alluvial deposits and within the clastic sedimentary rocks of Haddat Ash Sham and Ash Shumaysi formations. The shallow zone is characterized with a saturated thickness of 3–20 m and water is found under confined to semi-confined conditions. Water levels were encountered at depths varying from 3 to 16 m in the alluvial wadi deposits and from 18 to 62 m in the sedimentary succession. The combinations of vertical electrical sounding, horizontal electrical profiling, and drilling led to the identification of groundwater resources in the study area. Resistivity soundings clearly identified the nature of the lithological depth and proved useful at identifying water-bearing zones. Significantly, the majority of the groundwater was found within the deep confined aquifer gravelly sandstone, rather than in the shallow unconfined aquifer.  相似文献   

The use of a mixed scheme: mixed hybrid finite elements method/finite volumes (MHFE/FV), for the modeling of contaminants transport in unsaturated porous mediums   总被引：1，自引：1，他引：0  

Gheris Abderahim  Meksaouine Mohammed 《Arabian Journal of Geosciences》2011,4(3-4):669-680

This work is intended for the development of a numerical method to simulate flows and solute transport in multiphasical porous medium taking into consideration the interaction of solid/solute. More precisely, the studied problem is modeled by a coupled system composed of an elliptical equation (for the flow) and an equation convection–diffusion–reaction (for the transfer). Numerical simulations were realistic for two-dimensional problems confirming the stability and efficiency of the combined scheme in the characterization of a pollutant transport through an unsaturated zone of an industrial site.  相似文献   

Modeling of gas generation from the Alam El-Bueib formation in the Shoushan Basin, northern Western Desert of Egypt     

Mohamed Ragab Shalaby  Mohammed Hail Hakimi  Wan Hasiah Abdullah 《International Journal of Earth Sciences》2013,102(1):319-332

The Shoushan Basin is an important hydrocarbon province in the northern Western Desert, Egypt, but the burial/thermal histories for most of the source rocks in the basin have not been assigned yet. In this study, subsurface samples from selected wells were collected to characterize the source rocks of Alam El-Bueib Formation and to study thermal history in the Shoushan Basin. The Lower Cretaceous Alam El-Bueib Formation is widespread in the Shoushan Basin, which is composed mainly of shales and sandstones with minor carbonate rocks deposited in a marine environment. The gas generative potential of the Lower Cretaceous Alam El-Bueib Formation in the Shoushan Basin was evaluated by Rock–Eval pyrolysis. Most samples contain sufficient type III organic matter to be considered gas prone. Vitrinite reflectance was measured at eight stratigraphic levels (Jurassic–Cretaceous). Vitrinite reflectance profiles show a general increase of vitrinite reflectance with depth. Vitrinite reflectance values of Alam El-Bueib Formation range between 0.70 and 0.87 VRr %, indicating a thermal maturity level sufficient for hydrocarbon generation. Thermal maturity and burial histories models predict that the Alam El-Bueib source rock entered the mid-mature stage for hydrocarbon generation in the Tertiary. These models indicate that the onset of gas generation from the Alam El-Bueib source rock began in the Paleocene (60 Ma), and the maximum volume of gas generation occurred during the Pliocene (3–2 Ma).  相似文献   

Erratum to: Liquid hydrocarbon generation potential from Tertiary Nyalau Formation coals in the onshore Sarawak, Eastern Malaysia     

Mohammed Hail Hakimi  Wan Hasiah Abdullah 《International Journal of Earth Sciences》2013,102(1):349-349

  相似文献   

Upper Jurassic record of Polyphylloseris (Egypt, Northern Sinai)     

Mohammed Gameil  Franz T. Fürsich  Mohammed H. Mandurah 《Arabian Journal of Geosciences》2013,6(11):4271-4278

Genus Polyphylloseris is a scleractinian colonial coral that has been established by d’Orbigny (1849) from the Neocomian of Yonne, France. The genus is characterized by having elevated domal calices that are mammillar or craterlike in shape and with porous confluent septa. Columella is absent or rudimentary, and the lower surface of the corallum is covered with a thick and wrinkled holotheca. Specimens having the above-mentioned characteristics have been collected from the Upper Jurassic Arousiah Member of the Masajid Formation (Callovian–Oxfordian) of Gebel Maghara, Northern Sinai, Egypt. They are characterized by having a cupolate colonial form and porous pennulate septa which reach 40–50 in number. Based on these characters and other characters such as density of septa, height, and width of mammillar calices, the studied material is attributed to a new species named Polyphylloseris magharensis. The new species is a first undoubted record of Polyphylloseris in the Jurassic. Previously recorded undoubted ages of the genus are Early and Late Cretaceous. The fewer number of septa and the smaller-sized and closer mammillar calices allow differentiation of the species from other species such as Polyphylloseris icaunensis d’Orbigny and Polyphylloseris convexa d’Orbigny.  相似文献   

High-resolution facies and porosity models of the upper Jurassic Arab-D carbonate reservoir using an outcrop analogue, central Saudi Arabia     

Hassan Eltom  Mohammed Makkawi  Osman Abdullatif  Khalid Alramadan 《Arabian Journal of Geosciences》2013,6(11):4323-4335

Subsurface models of hydrocarbon reservoirs are coarse and of low resolution when compared with the actual geologic characteristics. Therefore, the understanding of the three-dimensional architecture of reservoir units is often incomplete. Outcrop analogues are commonly used to understand the spatial continuity of reservoir units. In this study, a Late Jurassic outcrop analogue for the Arab-D reservoir of central Saudi Arabia was used to build a high-resolution model that captures fine geologic details. Subsurface reservoir lithofacies were matched with those from the studied outcrop, and porosity values derived from published core and well log data from the Ain Dar, Uthmanyah, and Shudgum areas of the Ghawar Field, eastern Saudi Arabia, were then applied to the equivalent lithofacies in the outcrop. Maximum, minimum, and average subsurface porosity for each lithofacies were distributed in the facies model using a geostatistical algorithm to produce nine porosity models for the field data. Several realisations were run to visualise the variability in each model and to quantitatively measure the uncertainty associated with the models. The results indicated that potential reservoir zones were associated with grainstone, packstone, and some wackestone layers. Semivariogram analysis of the lithofacies showed good continuity in the N-S direction and less continuity in the E-W direction. The high-resolution lithofacies models detected permeability barriers and isolated low porosity bodies within the potential reservoir zones. This model revealed the porosity distribution in areas smaller than one cell in the subsurface model and highlighted the uncertainty associated with several aspects of the model.  相似文献   

Hydrocarbons generation potential of the Jurassic–Lower Cretaceous Formation, Ajeel field, Iraq     

Thamer Khazaal Al-Ameri  Nagham Mohammed Al-Jubouri  Murtadha J. Isa  Rami Eidan Al-Azzawi 《Arabian Journal of Geosciences》2013,6(10):3725-3735

Organic geochemical analysis and palynological studies of the organic matters of subsurface Jurassic and Lower Cretaceous Formations for two wells in Ajeel oil field, north Iraq showed evidences for hydrocarbon generation potential especially for the most prolific source rocks Chia Gara and Sargelu Formations. These analyses include age assessment of Upper Jurassic (Tithonian) to Lower Cretaceous (Berriasian) age and Middle Jurassic (Bathonian–Tithonian) age for Chia Gara and Sargelu Formations, respectively, based on assemblages of mainly dinoflagellate cyst constituents. Rock-Eval pyrolysis have indicated high total organic carbon (TOC) content of up to 18.5 wt%, kerogen type II with hydrogen index of up to 415 mg HC/g TOC, petroleum potential of 0.70–55.56 kg hydrocarbon from each ton of rocks and mature organic matter of maximum temperature reached (T_max) range between 430 and 440 °C for Chia Gara Formation, while Sargelu Formation are of TOC up to 16 wt% TOC, Kerogen type II with hydrogen index of 386 mg HC/g TOC, petroleum potential of 1.0–50.90 kg hydrocarbon from each ton of rocks, and mature organic matter of T_max range between 430 and 450 °C. Qualitative studies are done in this study by textural microscopy used in assessing amorphous organic matter for palynofacies type belonging to kerogen type A which contain brazinophyte algae, Tasmanites, and foraminifera test linings, as well as the dinoflagellate cysts and spores, deposited in dysoxic–anoxic environment for Chia Gara Formation and similar organic constituents deposited in distal suboxic–anoxic environment for Sargelu Formation. The palynomorphs are of dark orange and light brown, on the spore species Cyathidites australis, that indicate mature organic matters with thermal alteration index of 2.7–3.0 for the Chia Gara Formation and 2.9–3.1 for the Sargelu Formation by Staplin's scale. These characters have rated the succession as a source rock for very high efficiency for generation and expulsion of oil with ordinate gas that charged mainly oil fields of Baghdad, Dyala (B?aquba), and Salahuddin (Tikrit) Governorates. Oil charge the Cretaceous-Tertiary total petroleum system (TPS) are mainly from Chia Gara Formation, because most oil from Sargelu Formation was prevented passing to this TPS by the regional seal Gotnia Formation. This case study of mainly Chia Gara oil source is confirmed by gas chromatography–mass spectrometry analysis for oil from reservoirs lying stratigraphically above the Chia Gara Formation in Ajeel and Hamrine oil fields, while oil toward the north with no Gotnia seal could be of mainly Sargelu Formation source.  相似文献   

The potential of hydrocarbons generation in the Chia Gara Formation at Amadia area, north of Iraq     

Sahar Y. Jasim 《Arabian Journal of Geosciences》2013,6(9):3313-3318

Sixteen rock samples of outcrop of Chia Gara Formations from the type locality area, south of Amadia, North Iraq showed evidences for hydrocarbon generation potential by palynological studies. These analyses include age assessment of Upper Jurassic (Tithonian) to Lower Cretaceous (Berriasian) age based on assemblages of mainly dinoflagellate cyst constituents. Qualitative studies are done in this study by textural microscopy used in assessing amorphous organic matter for palynofacies type belong to kerogen type A of Thompson and Dembiki (Int J Coal Geol 6:229–249, 1986) which contain brazinophyte algae, Tasmanites, and foraminifera test linings, as well as the dinoflagellate cysts and spores, deposited in dysoxic–anoxic environment. The palynomorphs are of dark orange and light brown, on the spore species Cyathidites australis, that indicate mature organic matters with thermal alteration index of 2.7–3.0 by Staplin’s scale. These characters and total organic carbon of 0.5–8.5 wt% have rated the succession as a source rock for high efficiency for generation and expulsion of oil with ordinate gas that charged mainly oil fields of Tawqi. Some oil is released from the Chia Gara Formation to charge the Cretaceous–Tertiary total petroleum system.  相似文献