Radwan, A. Bahgat (Qatar University) | Ahmed, Said Elmi (Qatar University) | Kahraman, Ramazan (Qatar University) | Montemor, F. M. (Universidade de Lisboa) | Ali, Kamran (DHA Suffa University) | Mahmoud, Abdelrahman Adel (Qatar University) | Shakoor, R. A. (Qatar University)
Corrosion is a major cause of materials and equipment failure in the oil and gas industry, and its prevention is crucial to ensure reliability of the assets. Towards, this goal, Ni-B/AlN nanocomposite coatings were synthesized through electrodeposition technique and their properties were investigated. It is noticed that the incorporation of AlN nanoparticles into Ni-B matrix has a pronounced effect on its surface, structural, mechanical and anticorrosion properties. The improved properties of Ni-B/AlN nanocomposite coatings make them attractive for many industrial applications.
Over the years, nanostructured coatings have gained great attentions in many engineering applications because of superior structural, mechanical, electrical, thermal and anticorrosion properties. The small grain size (<100 nm) of nanostructured coating results in superior attributes that may be sometimes entirely novel when compared to the conventional coatings with coarse grained structure. The appealing properties of nanostructured materials make them attractive for hydrogen storage and purification, electrodes fuel cells, batteries, wear resistance hard coatings (automobiles, aerospace), synthesis of soft magnets and catalysts etc.1,2
Ni-B coatings possess highly desirable attributes such as high hardness, high wear resistance, uniform thickness, high density, low porosity and good ductility. Such properties make them strong candidates towards applications in automobile, aerospace, petrochemical and many other related industries. Instead of such core competencies, the Ni-B coatings have certain limitations and weaknesses such as inferior anticorrosion properties as compared to Ni-P coatings. It limits their application in more demanding industries such as oil and gas, etc. Therefore, it is necessary to improve the characteristics of Ni-B coatings so that it can be used in more aggressive and harsh conditions. In this regard, a well competent research work has already been in progress and different research groups have made attempts to improve the properties of binary Ni-B coatings. Some of the strategies include the incorporation of either alloying elements such as Zn3 or insoluble, hard second phase particles like Y2O34, CeO25, Al2O36, and ZrO27 etc.
Wave breaking is an important phenomenon in coastal protection due to the dissipated energy. Such phenomenon is also responsible for the nearshore sediment transport caused by the generated turbulence and currents.
The aim of this work is to apply two different CFD numerical codes to simulate accurately spilling and plunging wave breaking. Numerically simulated free surface elevations and velocities were compared with experimental data and also with numerical results published elsewhere.
In spite of the differences that were found between the performances of the numerical models, they reproduced well the experimental data.
Depth induced wave breaking is a rather complex process usually associated with energy dissipation, splash, air entrainment and an enhancement of turbulence. The type of wave breaking is of the utmost importance, especially because it determines the level of energy dissipation. On the other hand, the location of the wave breaking and the air entrained are crucial for, amongst other effects, the associated sediment transport and for the stability of maritime structures.
The wave breaking dynamics have been the subject of a number of studies. Svendsen (1987) analyzed the turbulence in the surf zone and the energy dissipation. Rivero and Arcilla (1995) developed a formulation to evaluate the vertical wave shear stress distribution in the surf zone. Recently, Zou et al. (2006) proposed a new approach to describe the vertical distribution of the wave shear stress in a variable water depth with breaking and non-breaking wave conditions. The theoretical predictions were compared with field measurements provided by Wilson et al. (2014).
This paper is a study of the potential for underground storage of gas in salt caverns in Portugal, in order to find the volume of gas that can be stored in the national territory. It is emphasized that in Portugal there are plenty of salt dome formations that can provide solutions for storage. For a better understanding, a characterization of the global market for gas will be made, giving greater focus to the current situation of the European Union, and described the methodologies most used for underground gas storage.
The crises between Russia and Ukraine in 2009, have demonstrated the European Union energy system vulnerability as some countries threaten to break natural gas stocks. This scenario is compounded by the high EU dependence of the Natural Gas from Russia. In this context the underground storage of natural gas is presented with a good solution to minimize this problem.
This paper is a study of the potential for underground storage of gas in salt caverns in Portugal, in order to find the volume of gas that can be stored in the national territory. It is emphasized that in Portugal there are plenty of salt dome formations that can provide solutions for storage. For a better understanding, a characterization of the global market for gas will be made, giving greater focus to the current situation of the European Union, and described the methodologies most used for storing gas underground.
2. World Market
In this chapter will be characterized the global market for natural gas (Reserves, Production and Consumption), placing greater emphasis on the state of the EU.
The proven reserves worldwide have grown steadily over the years, in 1980 were at the level of 80 000 bcm, rising to 180 000 bcm in 2006 (GILARDONI, 2008).
2.1.1 European Union
The main reserves of the EU are held by two countries: the Netherlands and the UK.
Until this day the reserves have been declining, reaching 2 500 bcm in 2006, which represents a ratio (R/P) of 13 years.
With the impressive technological development, the importance of Acoustic Emission Technique (AET) has been proved for various subjects in Rock Mechanics. In fact, acoustic emission monitoring has been studied since 1930’s both in metallic and rock materials, but this subject is still encouraging and challenging. In this paper, in situ stress determination by Small Flat Jack (SFJ) method in Panasqueira Mines (Portugal)AW36- D21 stope pillars was made. The in situ results were compared with those given by AET technique (Kaiser Effect) over schist specimens collected in the same stope. Results show that, AET represents a real low cost and timesaving alternative for in situ vertical stress determination methods.
Underground mining methods with natural support pillars (like room-and-pillar method, Figure 1) are, in the safety point of view, the main responsible structures to the stability of mining works. Thus, their design are extremely important in underground mining projects.
As generally accepted, pillar design is based in the safety factor concept which is a relation between pillar strength and applied load by the underground excavation structure.
However, underground excavation design and operation requires precise information about in situ state of stress. Presently, there are several state of stress measuring methods in rock masses, like (Brady & Brown, 1985; Lavrov, 2003; Fjaer et al., 2008):
• Bidimensional or tridimensional methods, with the application of bi- or tridimensional load cells, like the ones described by Leeman and Hayes (1966), Worotnicki and Waltson (1976);
• Small flat jack (SFJ) method, when is possible to get direct access to the state of stress;
• Leak-off tests (LOT) or extended leak-off tests (XLOT), applied in oil well drilling:
• Hydraulic fracturing methods and overcoring.
These methods are time consuming and require high specialized handwork. Also, several times, they don’t give necessary precision and, for this reason, newtechniques for in situ state of stress monitoring are being developed.
Carbonate reservoirs are commonly heterogeneous and their reservoir quality results from complex interactions between depositional facies and diagenetic processes. The Diagenetic Diagram is a powerful tool that helps in the characterization of the diagenetic processes that have affected the reservoir. From this knowledge, it is possible to significantly improve the understanding of the reservoir's pore system and permeability distributions, which are key factors for development optimization and production sustainability.
A multi-scale and multi-method study (petrography, blue-dye impregnation, selective staining and porosity determination) of Middle Jurassic carbonates from the Lusitanian Basin (Portugal) has been undertaken, to find the best systematic approach to these reservoirs. It has involved thorough diagenetic characterization of each lithotype (lithofacies, texture, porosity, qualitative permeability assessment and diagenetic evolution). The study area was selected based on its excellent and varied exposures of carbonate facies and availability of core.
Methodological and terminological challenges were faced during the study, especially dealing with data coming from several scales (macro, meso, and micro). In order to overcome these challenges, a diagenetic diagram was developed and applied to the selected rocks. It is a tool that allows the integration of data coming from outcrops, hand samples, cores, cuttings, thin sections, and laboratory experiments.
This is carried out in a dynamic, guided, systematic, and rigorous way, enabling the evaluation of the relationship between facies, diagenetic evolution and pore systems. The latter are characterized regarding size, geometry, distribution, and connectivity. This enables the identification and characterization of permeability heterogeneities in the rocks. It was concluded that the main porosity class (i.e. secondary) was created by diagenetic processes.
The proposed method has strong application potential for: detailed characterization and understanding of porosity and permeability in carbonate reservoirs, from a diagenetic evolution and fluid flow perspective (e.g. SCAL and pore system description); definition of diagenetic trends for modeling petrophysical properties and rock types. In this regard, the method is being applied to a Valanginian carbonate reservoir in Kazakhstan, and some preliminary results are presented in this paper. Refining this technique may be helpful for similar carbonate studies, enhancing the results of typical diagenetic studies by improving the characterization of reservoir properties at various scales, thus contributing to a more sustainable exploitation of hydrocarbon reservoirs.