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Value Creation with Multi-Criteria Decision Making in Geosteering Operations
Get PDFDue to escalated drilling costs, the petroleum industry has been attempting to access the largest possible hydrocarbon resources with the lowest achievable costs. Multiple well objectives are set prior to the start of drilling. Then, a geosteering approach is implemented to help operators achieve these objectives.A comprehensive literature survey has been performed on geosteering case histories, including many cases with multiple objectives. We found that the listed objectives are often conflicting and expressed in different measures. Furthermore, none of the cases from the reviewed literature has discussed a systematic approach for dealing with multiple objectives in geosteering contexts. Without implementing a well-structured approach, decision makers are likely to make judgments about the relative importance of each objective based on previous experiences or on approximate methods. Research shows that such decision-making approaches are unlikely to identify optimal courses of action.In this paper, we propose a systematic method for making multi-criteria decisions in geosteering context. The method is constructed such that it is applicable for real-time operations. Results show that different decision criteria can have significant impact on well success as measured by its trajectory, future production, cost, and operational efficiency
Numerical Study of Heat Transfer and Comfort Conditions in an Air-Cooled Ventilated Room with a Human Heat Source
Get PDF A numerical study of the turbulent heat transfer in a two-dimensional rectangular air-cooled ventilated room with a human being as a discrete heat source was carried out in order to determine the best ventilation configuration. The results were obtained for a cavity of 2.5 m of height and 3.0 m of width. The right and left vertical walls of the cavity were kept at 35°C and 25°C respectively, whereas the remaining walls were adiabatic. Three cases for the air inlet and outlet locations were considered for the analysis. The air enters to the cavity at 15°C with speeds between 0.2 m/s and 2.0 m/s. The emissivity of the cavity walls was considered as 0, 0.5 and 1. The results indicate that the configuration (A) (inlet on the lower part of the right vertical wall and outlet on the upper part of the left vertical wall) offers the lowest average temperatures inside the room and the highest temperature distribution effectiveness
The Bioavailability and Evolution of Trace Metals in Environment: A Brief Review
Get PDFAs a kind of important pollutants, trace metals and the pollution have been become a concerned worldwide environmental problem. Despite the fact that the bioavailability of trace metals indicated by their speciation has been an indispensible parameter in the assessment and treatment of trace metal pollution, many studies suggest that the bioavailability of trace metals may change according to environmental conditions, and they can also transform between some speciation fractions. These transformations are related with factors such as the compositions, microorganism, time, and other physical-chemical conditions of the system. So, it is necessary to systematically understand and investigate for the factors to affect the transformation aside from analysis at certain time-place. The results of these understanding and investigations can be used for reasonably determining the allocation of financial and technical resources in natural and engineered processes with bringing about inspirations from the evolution of the speciation of the trace metals on environmental impacts
Sustainable Food Production in Greenhouses and Its Relations to the Environment
Get PDFA greenhouse is essentially an enclosed structure, which traps the short wavelength solar radiation and stores the long wavelength thermal radiation to create a favourable microclimate for higher productivity. The sun's radiation incident on the greenhouse has two parts: direct radiation and an associated diffuse sky radiation. The diffuse part is not focused by the lenses and goes right through Frensel lenses onto the surface of the absorbers. This energy is absorbed and transformed into heat, which is then transported via the liquid medium in copper pipes to the water (heat) storage tanks or, if used, open fish tanks. In this way, an optimal temperature for both plant cultivation and fish production can be maintained. Stable plant growth conditions are light, temperature and air humidity. Light for the photosynthesis of plants comes from the diffuse radiation, which is without substantial fluctuations and variation throughout most of the day. The air temperature inside the greenhouse is one of the factors that have an influence on the precocity of production. The selective collector acts in a more perceptible way on extreme air temperatures inside the greenhouse. Hence, the system makes it possible to avoid the excessive deviation of the temperature inside the greenhouse and provides a favourable microclimate for the precocity of the culture. Sediment and some associated water from the sediment traps are used as organic fertiliser for the plant cultivation. The present trend in greenhouse cultivation is to extend the crop production season in order to maximise use of the equipment and increase annual productivity and profitability. However, in many Mediterranean greenhouses, such practices are limited because the improper cooling methods (mainly natural or forced ventilation) used do not provide the desired micro-climatic condition during the summer of a composite climate. Also, some of these greenhouses have been built where the meteorological conditions require some heating during the winter, particularly at night. The worst scenario is during the winter months when relatively large difference in temperature between day and night occurs. However, overheating of the greenhouse during the day is common, even in winter, requiring ventilation of the structure. Hence, several techniques have been proposed for the storage of the solar energy received by the greenhouse during the day and its use to heat the structure at night. Reviews of such techniques are presented in this paper. Air or water can be used for heat transport. The circulating water is heated during the day via two processes. The water absorbs part of the infrared radiation of the solar spectrum. Since the water is transparent in the visible region, they do not compete with the plants that need it. Alternatively, the water exchanges heat with the greenhouse air through the walls. At night, if the greenhouse temperature goes down below a specified value, the water begins to circulate acting as heat transfer surfaces heating the air in the greenhouse. This communication describes various designs of low energy greenhouses. It also, outlines the effect of dense urban building nature on energy consumption, and its contribution to climate change. The objectives are to produce vegetables in greenhouse environment. Measures, which would help to save energy in greenhouses, are also presented. It also enabled the minimisation of temperature variation and, hence avoided the hazard of any sudden climatic change inside the greenhouse
Thermocapillary Flow in an Annular Two-Layer Liquid System
Get PDF By means of a hybrid lattice Boltzmann method, thermocapillary flow, driven by the surface tension owing to a horizontal temperature gradient along the interface in immiscible two-layer liquid system, is simulated numerically. The dynamic behavior of the interface is captured by using phase-field theory. The dependence of flow and interface deformation on the density ratio, Capillary number and aspect ratio, is investigated
Water Security, The Nexus Of Water, Food, Population Growth and Energy
Get PDFIssues causing increased water stress and availability throughout the world are complex. The importance of supply-side issues arising from increasing urbanization, causing localized levels of water stress, is described. Further, while the world population has doubled over the last 50 years, water use has tripled. Water use rates have increased (from 400km3 per year per billion people in 1965, to the current level of 600km3 per year per billion people in 2015), as a result of population growth with its associated food and energy implications, and dietary shifts of populations.Water demands in 2025 are projected to be 1500km3 per year, or 60% more than volumes in 2015. The findings in a case study in the Zambezi River basin indicate that while climate change is projected as 25% of the projected impact to future water security issues, 75% of water security issues are attributable to population increases (and its related food, energy, and changing dietary habits) and hence, population increases represent a greater threat to water security
Applicability on Static-Dynamic Verification Method for Seismic Design of Steel Tubular Bridge Piers with Cruciform Plates
Get PDF Steel tubular bridge pier with inner cruciform plates has high seismic performance. In this paper, the applicability of static-dynamic verification method for seismic design of steel tubular bridge piers with inner cruciform plates is studied. The ultimate strength and state of steel tubular stub columns with inner cruciform plate subjected to compression and bending were investigated through finite element analysis. The validity of the proposed design formula of the failure strain which was obtained from the stub column analysis was examined by analysis on tubular steel bridge piers with inner cruciform plates under cyclic loading. The dynamic response analysis of the same steel bridge piers was carried out on the basis of the spring-mass model and the fiber element model. These results indicated the static-dynamic verification method of the seismic response analysis through the spring-mass model are good agreement with dynamic verification method of seismic response analysis by the fiber element model
Computing the Hermitian Positive Definite Solutions of a Nonlinear Matrix Equation
Get PDFIn this paper, we consider a nonlinear matrix equation. We propose necessary and sufficient conditions for the existence of Hermitian positive definite solutions. Some necessary conditions and sufficient conditions for the existence of Hermitian positive definite solutions of this equation is also derived. Based on the Banach fixed point theorem, the existence and the uniqueness of the Hermitian positive definite solution are studied. An iterative method for obtaining the Hermitian positive definite solution of this equation is proposed. Finally, some numerical examples are presented to illustrate the performance and efficiency of the proposed algorithm
CFD Modeling of Film Cooling Flow with Inclined Jets
Get PDFFilm cooling has been widely used to control temperature of high temperature and high pressure blades. In a film cooled blade the air taken from last compressor stages is ejected through discrete holes drilled on blade surface to provide a cold layer between hot mainstream and turbine components. A comprehensive understanding of phenomena concerning the complex interaction of hot gasses with coolant flows in a vane passage plays a major role in the definition of a well performing film cooling scheme. In this study turbulent film cooling flow has been studied numerically. The computational simulation is conducted by employing the Reynolds Averaged Navier-Stokes (RANS) approach. The standard k-e model with enhanced wall treatment has been implemented for modeling the turbulent flow. Effects of different cooling holes temperature have been studied on the surface of the blade and as results show the temperature of the surface reduces significantly as the temperatures of the cooling holes decreases
Selected Phenomena of Spontaneous Electric Noise
Get PDF Recently a modified Drude model of the valence electron gas in metals was investigated mathematically. The implications of this model suggest that the thermal noise voltage increases for example with the length of the metallic conductor. This observation prompted us to carry out some innovative experiments whose outcomes confirmed qualitatively the Drude model. We discuss some implications of this model in the light of the performed measurements