Qatar Foundation Annual Research Forum Volume 2010 Issue 1
- تاريخ المؤتمر: 12-13 Dec 2010
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2010
- المنشور: ١٣ ديسمبر ٢٠١٠
151 - 166 of 166 نتائج
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Improving mechanical and thermal properties of AZ31 magnesium alloy through simultaneous addition of aluminum and nano-alumina
المؤلفون: Md Ershadul Alam, S Han, QB Nguyen, M Gupta and AMS HamoudaAbstractIn the present study, AZ51 magnesium alloy and AZ51-Al2O3 magnesium nano-composite was successfully synthesized incorporating elemental aluminium (Al) (2 wt.%) and simultaneous addition of Al (2 wt.%) and nano-sized Al2O3 (1.5 vol.%) into pure AZ31 alloy, respectively, using an innovative disintegrated melt deposition technique followed by hot extrusion. Microstructural characterization studies revealed uniaxial grain size, reasonably uniform distribution of particulates/intermetallics in the matrix and minimal porosity. Thermal properties characterization revealed that addition of both Al and nano-sized Al2O3 reduced the coefficient of thermal expansion (CTE) of monolithic AZ31. The presence of both Al2O3 nanoparticulates and aluminum also assisted in improving overall mechanical properties of AZ31 magnesium alloy. Microhardness can be increased by about 67% with the addition of Al and Al2O3 into pure AZ31 when compared to pure AZ31 alloy. Newly developed AZ51-Al2O3 nano-composite also exhibited higher modulus of elasticity (80%), 0.2% yield strength (17%), ultimate tensile strength (14%), ductility (26%) and work of fracture (46%) when compared to a monolithic AZ31 alloy. The results suggest that both the new alloy and composite have significant potential in diverse engineering applications when compared to the AZ31 alloy and can be used by weight critical aerospace and automotive industries to save energy.
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Holocene sabkha and coastal systems of Qatar: models for the interpretation of ancient Arabian plate carbonate evaporite reservoirs and coastal management
المؤلفون: Jeremy JamesonAbstractFacies tracts, sediment types, stacking patterns, and diagenetic histories of Holocene sabkhas of Qatar provide compelling analogues for the interpretation of ancient, carbonate-evaporite sequences of the Arabian Plate. The use of modern analogues to aid in the interpretation of geological and engineering data is well established in the petroleum industry. Comparison of sabkhas from different physiographic regions of Qatar that formed during the latest Holocene cycle of sea level rises reveals new insights into the characterization of ancient rocks. These observations provide the basis for a revision of the definition of facies tracts described in the geological literature as sabkhas.
This study reports on a country-wide study of the sedimentation history of coastal areas, based on extensive field mapping, geotechnical studies, age dating and geochemistry. Data is integrated in ArcGIS, a relational database. The results are equally valuable in conservation, environmental and geotechnical studies and archaeological research and teaching.
Coastal areas of Qatar are marked by extremely low relief, with the result that high-frequency oscillations in sea level create offsets in facies tracts. Age dating reveals that inland sabkhas are relicts of a high stand in sea level approximately 4000-6000 years ago. These areas are presently subaerially exposed and eroding. Extensive pedogenic modification of marine sediments (burrowing, infiltration, micrite precipitation) creates characteristic textures. Groundwater modification includes extensive precipitation of CaSO4, halite,lime micrite, and dolomite.
The variability observed in Qatar sabkhas alters the way in which a common modern analogue is applied to the interpretation of subsurface data. These observations warrant revision of the definition of a sabkha. We propose that sabkhas are normal, coastal sediments, modified by near-surface groundwater saturated in CaSO4. A sabkha is a diagenetic overprint, not a depositional system. This proposed model helps aid in recognition of ancient sabkhas.
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A new risk-based approach for alarm system design
المؤلفون: Salim Ahmed and Faisal KhanAbstractIncreasing demands for higher efficiency and strict environmental regulations for process industries have led to the development of sophisticated control technologies and smart sensors. However, improved control mechanisms and better sensors have not been able to eliminate abnormal operating conditions. As a result operator interventions are routinely required. Alarms are at the forefront of the safety system in a plant to indicate the need for such interventions. The main purposes of an alarm is to warn of a possible critical condition and to seek the attention of an operator and thus to prevent, control and mitigate the effects of an abnormal situation. However, on many occasions, alarms have been reported as a contributor to abnormal events and the single variable based alarm system design has been identified as a main reason for that. In this article, we present a systems approach to design, analyze and prioritize alarms. By a system, we refer to a set of variables within a process.
An alarm is activated based on the risk associated with the state of the variables in a system. The objectives are to integrate risk estimation with alarm design and to reduce the number of alarms. First, the process variables are grouped to be represented by a number of systems. Alarms are then assigned to each system instead of individual variables. From the measured value of the variables, the risk associated within the individual system is estimated. Also from the relationships among the variables, future risk associated with each system is evaluated. Finally, the overall risk for a particular system is obtained from the current and predicted risk and comparing the overall risk with a predefined threshold value, a decision regarding alarm activation is taken. Once a set of alarms are activated, they are prioritized based on their severity. Also for the analysis of an alarm, the risk associated with individual variables under a system is analyzed and, finally, proper operator action is suggested to mitigate the abnormal situation.
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First-ever research on the basic ecology of the Ethiopian hedgehog (Paraechinus aethiopicus) in Qatar
المؤلفون: Nobuyuki YamaguchiAbstractBiodiversity conservation attracts much attention all over the world, highlighted in 2010, the United Nation's International Year of Biodiversity. Effective biodiversity conservation needs basic biological and environmental information, including the behavior and ecology of organisms. The Ethiopian hedgehog (Paraechinus aethiopicus), which is well adapted to the desert environment, is a common species in Qatar and yet little is known concerning their behavior and ecology. We are conducting the first ever research in the Gulf Cooperation Council (GCC) countries on the ecology and behavior of the Ethiopian hedgehog using radio-tracking, supported by the Undergraduate Research Experience Programme (UREP) awarded by the Qatar National Research Fund. The project is still ongoing and we have captured 48 different hedgehogs between April and June 2010, and put radio-tags on 13 (six females and seven males) animals so far. We followed them to collect data for investigating their spatial patterns and habitat preferences during the breeding season (spring and summer) where we found that males’ ranges are larger than those of females. We are currently conducting our fieldwork to investigate these ranges during the non-breeding season (autumn and winter). One of our hypotheses is that males’ ranges during the non-breeding season would be smaller than those during the breeding season whilst there would be no clear difference in females range. We expect that we would be able to collect enough data by December to present the results at the Qatar Foundation Annual Research Forum.
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Potentials for commercialization of novel Fischer-Tropsch reactor technology
المؤلفون: Nimir Elbashir, Eman Tora, Elfatih Elmalik and Mahmoud El HalwagiAbstractThis paper comprises of a preliminary in-depth analysis of the techno-economic criteria for the Fischer-Tropsch synthesis (FTS) solvent selection. Both conventional media (i.e. gas phase FTS and liquid phase FTS) as well as non-conventional media (near-critical and supercritical phase FTS) were examined, with an emphasis on non-conventional media FTS for the design and commercialization of a novel FTS reactor technology.
Supercritical and near critical fluids (SCFs) are attractive for several reasons, highlighted by their ability to overcome some of the major limitations of current commercial technologies (e.g. transport limitations in the slurry reactor, and thermal limitations in multi-tubular reactors). Due to single phase operation of SCFs, these solvents are unique media for chemical reactions as they operate with densities that are sufficient to afford substantial dissolution power, while also providing diffusivities that are higher than normal liquids and viscosities that are lower than their liquid counterparts.
High temperature Fischer-Tropsch (HTFT) was the center of examinations, but LTFT was considered as well. A wide array of hydrocarbon solvents was reviewed, ranging from propane to decane, with numerous blends of two or more of the mentioned paraffins. Several fuel cuts were studied as well, such as light and heavy naphtha and diesel.
Understanding the transport and thermodynamic behavior as well as economic benefit of these said solvents is essential to the success of an advanced FTS reactor model. Also, the interaction of the solvents with in-situ reaction mixture and products further insures single-phase operation and feasibility.
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Supported gold nanocatalyst for low temperature CO oxidation and combustion of volatile organic compounds (VOC)
المؤلفون: Khaled SaoudAbstractCarbon monoxide (CO) and volatile organic compounds (VOC), such as butadiene and isoprene, are air pollutants emitted by many industrial sources, such as burning of wood and fuel with poor ventilation, and by natural sources including forest fires or volcanic eruptions. It was found that these compounds are also significantly abundant in many industrial processes. Therefore, low-temperature catalytic oxidation of CO and combustion of VOC is one of the most important problems in catalysis, since even small exposures to CO or VOC (ppm) can be lethal. Catalytic oxidation is one effective method of removing CO.
Nanoparticle catalysts are characterized by a large surface area, high dispersion and strong metal-support interaction. It is therefore expected that nanoparticle catalysts would show high catalytic activity for the low temperature oxidation of CO.
Our results demonstrate the application of the vapor phase synthesis to synthesize supported and unsupported nanoparticle catalysts for CO oxidation. The method is based on the laser vaporization/controlled condensation (LVCC) technique of gold (Au) and copper (Cu) nanoparticles supported on a variety of oxide supports such as CeO2, TiO2, CuO and MgO. Our results indicate that Au nanoparticles supported on CeO2 exhibit higher catalytic activity than Au supported on other oxides. This high activity is attributed to the strong interaction of Au with CeO2. The results also indicate that 5 % Au loading on CeO2 has higher activity than 2% Au or 10% Au.
The effect of preparation method on the catalytic activity is investigated. It was found that the catalytic activity for 5%Au/CeO2 prepared by the chemical (deposition-precipitation) method is higher than the catalytic activity of Au/CeO2 prepared by physical (LVCC).
In any combustion system, there are significant amounts of other toxic gases,besides CO, such as nitric oxide, butadiene, and isoprene. We investigated the catalytic activity of the Au/CeO2 nanoparticle catalyst in the presence of 1000 ppm of butadiene and in the presence of 1000 ppm of isoprene. Our results indicate the combustion of butadiene and isoprene to CO2 and H2O, as supported by the mass spectrum and the CO conversion curve.
Finally, the Au/CeO2 nanoparticle catalyst can be an active catalyst for selective CO oxidation at temperatures below 300oC even in the presence of VOC. Furthermore, this catalyst shows great promise for the low temperature combustion of VOC such as butadiene and isoprene.
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Study of interrelationship between atmospheric turbulence with oceanic wave motions
المؤلفون: Ahmad Assem Jichi, Reza Sadr and Arindam SinghaAbstractThe exchange of momentum between the wind and the ocean surface is the primary source of various oceanic phenomena, both in large (e.g., El Niño) and small-scales (e.g., generation of wind waves, storm surge and coastal upwellings). Based on the existing literature on wind-wave interaction, it can be suggested that a unique missing link exists between the standard atmospheric and oceanic-circulation models. This is due to the inherent difficulty in the theoretical formulation of the models describing the phenomena and experimental measurement of the contributing factors in the near ocean surface wind measurement and surface pattern dynamics.
An experimental site was acquired at the under-construction New Doha International Airport in Qatar to help throw light on the aforementioned difficulty. The site is in an area with light aircraft traffic and is surrounded by a 6m deep ocean and almost flat terrain in all directions. Wind velocity measured at more than 7m/s comes over the ocean surface around morning time. An array of three sonic anemometers, thermocouples, net radiometer, two digital cameras and a complete weather station are to be installed on the site. The sonic anemometers are intended to measure the wind velocity and direction at different elevations from the ocean surface. The digital cameras will work synchronously with the anemometers to acquire images of the ocean surface. A variation wave acquisition stereo system will be used to reconstruct the 3D elevation of the ocean wave based on the principle of stereo reconstruction. At the end, the plausible link between the atmospheric and oceanic phenomenon will be explored experimentally which will lead to a better prediction model.
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Genetic and environmental variation among Qatari date palm cultivars assessed by DNA markers
المؤلفون: Talaat AhmedAbstractDate palms are generally propagated by separating the offshoots produced by individual trees. This method maintains the genetic integrity of date palm cultivars. However, well known date palm cultivars that are grown in different environments show little differences in fruit morphology and quality such as color and sweetness. The objective of the present research project is to analyze the genetic diversity among most common cultivars of Qatari date palms as well as the genetic variation within each cultivar grown in different environments in Qatar. Samples of the five most common date palm cultivars in Qatar; Khalas, Sheshy, Rezezy, Barhee and Khanezy were collected at three locations with different environments Al-Shamal, Al-Khour and Al-Rayan, Qatar. For each cultivar, samples were collected from three trees that showed little variation in their fruit morphology and quality. Genetic similarity or diversity among and within these cultivars was then analyzed using Inter Simple Sequence Repeat (ISSR) markers. A total of 18 ISSR single primers were used to amplify DNA bands using genomic DNA from the date palm samples. All of the primers used have amplified polymorphic bands in the studied cultivars either among the cultivars or within each cultivar in different cultivated environments. The results indicate the existence of genetic variations among the studied cultivars. Moreover, trees of the same cultivar that are grown in different environments show different DNA banding patterns explaining the variation in morphological and quality characters within each cultivar.
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Development of a high-speed, magnetically-loaded energy storage system
المؤلفون: Nazar Al KhayatAbstractWilliams Formula One (WF1) is one of the world's leading racing teams and has pioneered many technological innovations for racing cars in the past thirty years. Williams Technology Centre (WTC) is a recently formed company that is focused on exploiting one of the technologies WF1 has been nurturing for hybrid automotive applications, flywheel storage.
WTC business objectives are; the advancement of a cost-effective energy storage and power delivery pack to boost performance and improve efficiencies across multiple industries such as transportation, telecommunications, renewable energy, industrial, and aerospace. Applications of energy storage technology will lead to a reduction of fuel consumption, greenhouse emissions and improvement in system efficiency.
The enabling technologies for the WTC power pack are a magnetically loaded composite (MLC) rotor and a power electronics inverter (PEI). MLC is formed by mixing magnetic particles into a carbon based matrix filament. Glass and carbon fibres are added to the MLC layer to provide mechanical stability at high speed operation. The rotor is magnetized into a Halbach arrangement to eliminate back iron and generate a sinusoidal field distribution in the air gap.
Another key enabling technology that will be developed by WTC is the power electronics inverter. The inverter will regulate the machine input/output using advanced pulse width modulation techniques. Advanced motor control strategies are currently being investigated to maximise system efficiencies and robustness in case of faults.
Supported by a Qatar Foundation grant, WTC is currently building an engineering design office and electronic and mechanical engineering workshop to advance the development of a high power/energy flywheel. Efforts are ongoing to employ key specialists and development engineers to work on components and system engineering issues.
The full paper will discuss the key features of the flywheel technology and compare its performance against other technologies like super capacitors and lithium ion batteries. The paper will also review the ongoing engineering effort and technical advances necessary to support prototype/product development. Assessment of typical markets and applications will also be discussed.
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Biodiversity of Qatari Bacillus thuringiensis strains and molecular prediction of their biological activities and bioassays: for a safer and clean environment
المؤلفون: Asmaa Mohamed Raess, Mariam Al Muraikhi, Roda Al Thani and Jaoua SamirAbstractQatar's soil and environment are sources of beneficial bacterial strains and bacterial resources that should be first of all, identified, isolated, studied, used and valorized. In fact, the Qatari environment should be elective for many microbial genetic resources tolerant to high temperature, drought, salinity and hydrocarbon rich soil. Isolating microbial strains having biotechnological applications would be very beneficial not only for Qatar, but also for the Gulf region and other countries in the world. B. thuringiensis is a Gram-positive bacterium which produces, during sporulation, crystalline inclusions containing one or more deltaendotoxins, that are considered as the best biological insecticides as they are harmless for man and animal and act specifically against a wide variety of pathogenic insects, including pests and disease vectors. In this research project, we studied 31 crystal producing Qatari B. thuringiensis isolates, by the investigation of their plasmid patterns, crystal morphology, deltaendotoxin identification by SDS-PAGE, prediction of gene nature by PCR and insecticidal activities. The crystal morphology comparison showed that 22.5 % were spherical, 32.2 % were amorphous, 38.7 % were pyramidal and 6.4 % were bipyramidal. Based on the isolates plasmid patterns, 11 representative strains of the different classes were deeply studied. We used their molecular ribotyping and bioinformatic tools of sequence and BLAST alignment, to confirm that the studied isolates are B. thuringiensis strains. By SDS-PAGE, we showed that the deltaendotoxins produced by the different strains have different molecular weights. The PCR screening of these strains, using oligonucleotides specific for the genes cry1 and cry4, showed the presence of genes cry1A in two strains and allowed us to predict their potential insecticidal activities against lepidopteran larvae. Moreover, we used a B. thuringiensis israelensis in bioassay experiments against local mosquito Culex pipiens larveae and demonstrated the efficacy of such biological bioinsecticides on Qatari mosquitoes. These results are very encouraging and favour the use of B. thuringiensis local strain bioinsecticides for environmentally safe integrated pest management in this region.
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Development and control of homogenous charge compression ignition engines: a preliminary study
المؤلفون: Marwa Walid Fathy Abdelgawad, Reza Tafreshi, Jiafeng Sun, Reza Langari and Timothy JacobsAbstractFor many years, researchers have been trying to develop internal combustion engines with increased efficiency, while striving to satisfy stricter environmental regulations that limit the constituents of harmful emissions being produced. Homogenous charge compression ignition (HCCI) engines have provided a window of opportunity to make this happen since they incorporate the most ‘attractive’ features from both the standard spark-ignition engine and the compression-ignition engine, resulting in higher efficiencies and cleaner emissions. The main challenge of HCCI combustion is that it is triggered by the auto-ignition of the air-fuel mixture during compression, therefore, making it difficult to control while ensuring maximum efficiency.
This research project aims to apply HCCI technology in an attempt to improve the performance of stationary power generation systems in Qatar by developing a low emission – high efficiency natural gas engine. In this poster, we will demonstrate the experimental setup that has been installed and the control strategy that will be used to control ignition timing. The test bench is made up of a single-cylinder engine with intake and exhaust piping system, as well as sensory equipment. The engine is controlled and monitored by a data acquisition (DAQ) computer system. We will show that initial performance data, obtained under full load and at different engine speeds, are in accordance with the performance data from the manufacturer. In addition, a mathematical pressure model has been developed and compared with experimental data, which will be used as the primary input for the feedback control mechanism. We will explain the process in which engine control algorithms use instantaneous cylinder pressure measurements and appropriate thermodynamic relationships to determine the rate of heat release (ROHR). Measured ROHR will then be compared with acceptable rates and controlled using exhaust gas recirculation (EGR) and intake and exhaust manifold pressures and temperatures. Finally, further work to implement HCCI natural gas fueled engine will be discussed.
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Paper recycling at Qatar University
AbstractIn 2007, 2,500,000 tons of waste in Qatar was disposed of on the Umalafai landfill, of which 700,000 tons constituted domestic waste, However, only 4600 tons of this waste was discharged to be recycled, and of this 149 tons was paper waste. This high amount of waste paper in 2007, when the population of Qatar was 907,229 means that there should be even more waste as the population reached 1,900,000 in 2009. An immediate response should be taken, and the present research team believes that recycling is the best and easiest solution for this problem. In order to change people's habits, education and awareness programs are needed. A good place to start such a campaign is at educational institutions, such as Qatar University.
Qatar University, with a student population that exceeds 8000, makes a significant contribution to the development of society in Qatar, and plays an important role in leading the public and technology in sustainable protection of the environment.
The project made the students of Qatar aware of the importance of waste paper recycling, with the long term goal of transmitting this awareness to society as a whole. In this project we started paper recycling technology at Qatar University, which will be the starting point in educating society and making Qatar University a leading institution in recycling technologies. Paper recycling equipment will be purchased and installed at the newly built Research Center at Qatar University. The faculty and students of the project are collaborating with the local paper recycling company, Al-Suwaidi Paper Factory, in sharing technical information and building a long lasting collaboration.
The project helped the students understand the life cycle of paper and conducted a survey to gauge people's attitude towards paper recycling in Qatar. At the moment the students are constructing the first recycling plant in a teaching institution, in which the students will be able to synthesise various products made by recycled paper pulp. Attempts are made to develop pulp based composite material products and investigate their mechanical properties. The work will be accompanied by a public awareness campaign for paper recycling.
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Numerical methods in modeling and simulating fluid flow in heterogeneous and naturally fractured hydrocarbon reservoirs
المؤلفون: Ahmed Abushaikha, Tara Catherine LaForce, Martin Blunt, Ahmed El Sheikh, Jefferson Gomes and Chris PainAbstractMore than 50% of proven hydrocarbon reserves are in naturally fractured reservoirs (NFR) and fractures are present in most carbonate reservoirs. The heterogeneity of NFR material properties; permeability and porosity, is of large scale thus presenting a challenge in modeling fluid flow and recovery mechanisms numerically. For a large class of fractured reservoirs, especially for multiphase production mechanisms, the dual-medium approach, using a transfer function (TF) to represent the exchange term between fracture (flowing domain) and matrix (stagnant domain) is a good tool. However, the complexity of modeling the geometry of natural fractures and the advances in finite element method and computing power are calling for newer developments and tools to better model and simulate the unique two-timescale flow-system of these reservoirs.
The evaluation of various numerical methods in modeling fluid flow in highly heterogeneous NFR, such as finite element, finite volume, and finite difference, is the main goal of this research. This will be done through writing and benchmarking a simulator for each method and testing its capabilities in capturing the correct recovery mechanisms of NFR while maintaining accuracy in the numerical calculations. In this poster, we first present a literature review followed by an overview of the main equations used in fluid flow in reservoir engineering and their derivation and algebraic approximations in finite difference and finite element methods. After that, we present the results of the first 2D simulator written, using finite element finite volume (FEFV) and our preliminarily results in one and two phase (water-oil incompressible fluid) simple and heterogeneous models. Finally, a future plan of this research is discussed.
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Genetic diversity of date palm in Qatar
المؤلفون: Sara Hani Al Hadidi, Hala Nazeh Al Agha and Ahmed TalaatAbstractDate palm is the most important fruit tree in Qatar. Recently developed techniques, based on DNA markers, offer new tools for genetic analysis. The objectives of the present study are to analyze the genetic diversity among 15 different cultivars of date palm at the experimental farm of Qatar University using ISSR and SSR markers, and find out the genetic similarity and/or diversity among the well known date palm cultivars in the state of Qatar. DNAs were extracted from the young fresh leaves. A total of 34 primers of simple sequence repeat (SSR) and inter simple sequence repeat (ISSR) were tested for their ability to generate banding patterns in 15 date palm genotypes. However, 10 SSR and 18 ISSR primers successfully produced clear bands in all of the studied genotypes. Similarity coefficient matrix was computed to cluster the data and to draw precise relationships among the fifteen studied Qatari date palm genotypes. All date palm genotypes are inter-related in spite of their agronomic divergence. Genetic similarities and dendrogram could re-group the Qatari date palm cultivars in a way that one cultivar (Abu Main) was excluded from the group due to its dissimilarity with the other cultivars. Two cultivars (Barhee and Sultana) were much closer and could be considered as coming from one origin. The polymorphic patterns obtained suggested that the ISSR and SSR procedures constitute alternative approaches that are suitable to examine the date palm's genetic diversity at the DNA level.
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The Qatar Unified Imaging Project (QUIP)
المؤلفون: Moe TammiAbstractVCUQatar was recently granted QNRF funding to spearhead a highly collaborative and distributed project to advance knowledge of Qatar's history, traditions and culture. The Qatar Unified Imaging Project (QUIP) will identify and map the dispersed collections of Qatar's primary source materials in Qatar, India, Britain, and Denmark, then distribute selected results of that research from an open-access digital repository. The research team offers expertise in Gulf history, preservation, digitization, information access and education. Our expected outcome is the discovery and documentation of rich resource collections that will be made accessible for the benefit of the community and scholars without causing further deterioration of the original artifacts. QUIP will be an accessible resource to further the understanding of Qatar and the Arabian Gulf in relation to the rest of the world. Research will build on the work of the Qatar National Museum and the Ministry of Culture and expand access to disparate materials collected from or on Qatar, from the 18th to the 20th century. QUIP will produce a mapping of cultural orientation and a founding collection of digitized primary source materials. Using the European data structure and standardized metadata for classification of digital objects, ensures data portability and interoperability. QUIP will be sustained through collaborative partnerships with Qatar's cultural institutions, integration of the larger community of stakeholders and Qatar's commitment to UNESCO's Charter on the Preservation of the Digital Heritage.
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Fracture-related diagenesis in the carbonate carapace of a salt dome, Jebel Madar, Oman
المؤلفون: Iain Andrew MacDonaldAbstractThis study, carried out in the Qatar Carbonates and Carbon Storage Research Centre (QCCSRC) at Imperial College focuses on the interplay between fractures, diagenetic fluid flow and precipitation of diagenetic minerals in an exposed carbonate carapace of a salt dome in Oman. Understanding fault-related mineralization and the differences between diagenesis in the fractures and fracture walls compared to diagenesis in the rock matrix will help prediction of the reservoir quality of such fractured carapaces in the subsurface. The research questions addressed here are a) what controls the timing, distribution and geometry of fractures in the carapace of a salt dome?, and b) what controls the timing of the precipitation of minerals in the fracture network? To answer these questions, a dual approach combining structural geology with carbonate diagenesis is being applied. The origin of the fluids and their role in fracturing and diagenesis is being investigated by means of geochemistry and petrography and the processes of fracturing, fluid flow and the migration of fluids along pathways will be determined by reconstructing the structural history by a combination of field mapping and seismic interpretation. This dual approach is powerful and can be used to determine the history of fluid flow. Ultimately, the aim is to develop conceptual models linking fracturation and fluid flow during halokinesis with diagenesis.
Jebel Madar is situated in the southern foothills of the Oman Mountains and is a folded and fractured salt dome carapace comprising Jurassic and Cretaceous limestones. The structural history of the Jebel is currently being reconstructed using fracture analysis of structural data gathered during fieldwork. This will be augmented with the interpretation of seismic profiles. Initial results indicate that the dominant fracture orientations are ∼ N-S and NE-SW. Using the cross-cutting relationships of the fractures an attempt is being made to establish their chronology.
To understand the diagenetic history of the fracture infill, several techniques are being used including petrography, major and trace elemental analysis, fluid inclusion, and stable oxygen and carbon isotope analysis. An important observation made in the fractures of the Jebel Madar is that several generations of calcite cements exist, with crystals ranging in size from several centimetres in the centre of the fracture to compact, millimetre-sized crystals close to the host rock. In addition, in some fractures barite and calcite have been co-precipitated, an observation which, with the aid of fluid inclusion studies, could yield the composition and possible origin of the parent diagenetic fluids.
The presence of minerals in fractures indicates that these latter acted as fluid pathways. Initial stable isotope results suggest that the precipitating fluids were hot, with average values of δ 18O of –9.74 ‰ PDB and δ 13C of 1.19 ‰ PDB. Initial results indicate that the regional stress stimulated the local development of salt diapirs which produced local stress fields that totally dominated the timing and pattern of fracturing and fluid migration.
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