M. Behnia; K. Goshtasbi; M. Fatehi Marji; A. Golshani
Abstract
Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. ...
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Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. The crack tip element and a higher order boundary displacement collocation technique are used to study the hydraulic fracture propagation and its interaction with the pre-existing cracks and discontinuities in an elastic rock mass. The maximum tangential stress criterion (or -criterion) and the strain energy density criterion (SED) are used to obtain the fracture path and the results of both criteria are compared with each other. The comparison of numerical method with the results brought in the literature shows a good performance of the method in the case of interacting cracks.
F. Habashi
Abstract
Processing of minerals and production of metals has increased greatly in recent years. As a result, the quantities of waste material and pollutants have also increased. In many cases technology has changed to cope with the problem. Processes have been either modified to decrease emissions, or replaced ...
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Processing of minerals and production of metals has increased greatly in recent years. As a result, the quantities of waste material and pollutants have also increased. In many cases technology has changed to cope with the problem. Processes have been either modified to decrease emissions, or replaced by others that are less polluting even if at a higher cost. This paper briefly reviews examples in the ferrous and nonferrous industries.
M. Jahani; M. Noaparast; A. Farzanegan; G. Langarizadeh
Abstract
In this research, the efficiency of the comminution circuit as well as the efficiency of size classification equipment of the concentrator plant 2 of Sarcheshmeh copper complex was studied. The comminution circuit of this plant includes one SAG mill in a closed circuit with a vibrating screen and one ...
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In this research, the efficiency of the comminution circuit as well as the efficiency of size classification equipment of the concentrator plant 2 of Sarcheshmeh copper complex was studied. The comminution circuit of this plant includes one SAG mill in a closed circuit with a vibrating screen and one ball mill with a size classification system of hydrocyclone. The goal of this work was to calculate the proportion of each of these mills at energy consumption and generating suitable product for flotation as a further process. Three stages of sampling were performed and consumed energy was also modeled. The average efficiency of the initial ball mill was obtained which was equal to 72.96%. The average of the proportion of (consumed) energy by SAG and ball mills from total consumed energy at mills, was 44.65% and 55.35% respectively. The proportion of SAG and ball mills in producing the final product (particles finer than 74 µm) was 55.38% and 44.62% respectively. That is, the SAG mill produces about 10.76% more than the ball mill in the final product. The average consumed energy at SAG and ball mills to produce one ton of final product was 23.16 kWh/t and 36.05 kWh/t respectively. Thus, the ball mill consumes 12.89 kWh/t, more energy than the SAG mill in producing the final product. The average cyclones’ imperfection was 0.361 and therefore the average efficiency of cyclones’ separation was equal to 63.9% and the average efficiency of the vibrating screen was equal to 99.89%. As overflow of the initial cyclones (final product of comminution circuit) forms feed of rougher cells, cyclones’ inappropriate performance could severely influence the whole flotation process.
R. Gholami; A. Moradzadeh
Abstract
Reservoir permeability is a critical parameter for characterization of the hydrocarbon reservoirs. In fact, determination of permeability is a crucial task in reserve estimation, production and development. Traditional methods for permeability prediction are well log and core data analysis which are ...
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Reservoir permeability is a critical parameter for characterization of the hydrocarbon reservoirs. In fact, determination of permeability is a crucial task in reserve estimation, production and development. Traditional methods for permeability prediction are well log and core data analysis which are very expensive and time-consuming. Well log data is an alternative approach for prediction of permeability because they are usually available for all of the wells. Hence, attempts have been made to utilize well log data to predict permeability. However, because of complicate and non-linear relationship of well log and core permeability data, usual statistical and artificial methods are not completely able to provide meaningful results. In this regard, recent works on artificial intelligence have led to the introduction of a robust method generally called support vector machine (SVM). The term “SVM” is divided into two subcategories: support vector classifier (SVC) and support vector regression (SVR). The aim of this paper is to use SVR for predicting the permeability of three gas wells in South Pars filed, Iran. The results show that the overall correlation coefficient (R) between predicted and measured permeability of SVR is 0.97 compared to 0.71 of a developed general regression neural network. In addition, the strength and efficiency of SVR was proved by less time-consuming and better root mean square error in training and testing dataset.
P. Masoudi; B. Tokhmechi; A. Zahedi; M. Ansari Jafari
Abstract
Distinguishing productive zones of a drilled oil well plays a very important role for petroleum engineers to decide where to perforate to produce oil. Conventionally, net pay zones are determined by applying a set of cut-offs on perophysical logs. As a result, the conventional method finds productive ...
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Distinguishing productive zones of a drilled oil well plays a very important role for petroleum engineers to decide where to perforate to produce oil. Conventionally, net pay zones are determined by applying a set of cut-offs on perophysical logs. As a result, the conventional method finds productive intervals crisply. In this investigation, a net index value is proposed, then; diffusivity equation is utilized to calculate the proposed index value. The new net determination method is applied on the interval of Sarvak Formation of two datasets of two nearby wells. The best advantage of this newly developed net determination method is its fuzzy output. Fuzzy net pay determination is valuable in grading pay zones and not classifying all productive zones in a single class. Another advantage of the proposed net determination method is its higher accuracy in identifying productive zones in comparison with cut-off based method.
Z. Bahri; S.Z. Shafaei; M. Karamoozian
Abstract
Investigations were carried out on coal tailings by conventional cell and column flotation techniques. Tests were conducted to assess processing coal tailings of Alborz Markazi coal washing plant in Iran by column flotation. The effects of reagent type/dosage were investigated with conventional flotation ...
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Investigations were carried out on coal tailings by conventional cell and column flotation techniques. Tests were conducted to assess processing coal tailings of Alborz Markazi coal washing plant in Iran by column flotation. The effects of reagent type/dosage were investigated with conventional flotation and their results were used in the performance of column flotation. Also the effects of the air rate, the feeding rate, the wash water rate, the frother concentration, the collector dosage were evaluated with column flotation. These coal tailings have an average of 56% ash. This paper used factorial design to optimize grade and recovery of coal tailings. The column flotation results indicated concentrate produced under optimum conditions, kerosene, 2909 g/t; superficial air velocity, 0.96 cm/s; feeding rate, 3.6 lit/min; superficial wash water velocity, 0.98 lit/min; frother dosage, 350 g/t having an ash content of 12.11% and a combustible recovery of 28.51% was obtained.
M. Ataei; S.R. Torabi; B. Alizadeh Sevary
Abstract
Qomroud water conveyance tunnel (lot 1&2) with the length of 16 kilometers is considered as one of the greatest development and national projects in Iran. Since about 2 kilometers of tunnel pass through alluvium and the rest of the tunnel pass through various types of geological units, and due to the ...
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Qomroud water conveyance tunnel (lot 1&2) with the length of 16 kilometers is considered as one of the greatest development and national projects in Iran. Since about 2 kilometers of tunnel pass through alluvium and the rest of the tunnel pass through various types of geological units, and due to the complexity of geological condition and variety of effective criteria, suitable selection of excavation machine is crucial. In this respect, application of a suitable method which can select the best, according to the consideration of these entire criteria would be so important. One of the best decision making methods is Analytic Hierarchy Process (AHP) which has a strong theoretical basis. Using this method, this paper selects the most suitable excavation machine for Qomroud water conveyance tunnel. The results show that the EPB TBM Single Shield is the best alternative.
