Production capacity estimation by reservoir numerical simulation of northwest (NW) Sabalan geothermal field, Iran

A three dimensional numerical model of the northwest (NW) Sabalan geothermal system was developed on the basis of the designed conceptual model from available field data. A numerical model of the reservoir was expressed with a grid system of a rectangular prism of 12 km × 8 km with 4.6 km height, giving a total area of 96 km². The model has 14 horizontal layers ranging in thickness between 100 m to 1000 m extending from a maximum of 3600 to −1000 m a.s.l. Fifteen rock types were used in the model to assign different horizontal permeabilities from 5.0 × 10⁻¹⁸ to 4.0 × 10⁻¹³ m² based on the conceptual model.Natural state modeling of the reservoir was performed, and the results indicated good agreements with measured temperature and pressure in wells. Numerical simulations were conducted for predicting reservoir performances by allocating production and reinjection wells at specified locations. Three different exploitation scenarios were examined for sustainability of reservoir for the next 30 years. Effects of reinjection location and required number of makeup wells to maintain the specified fluid production were evaluated. The results showed that reinjecting at Site B, immediate adjacent to production zone, is most effective for pressure maintenance of the system.On the base of existing data and assumptions the reservoir can sustain producing fluid equivalent to 50 MW_e of electricity for more than 30 years. The reservoir can produce the maximum amount of fluids equivalent to 90-100 MW_e for only 5 years, but the production capacity decreases to 50 MW_e after 20 years of operation because of pressure and enthalpy drop. The reservoir can sustain 50 MW_e over 100 years that can be defined as a sustainable production level of the field.     

Kinetic speciation of Co(II), Ni(II), Cu(II), and Zn(II) in model solutions and freshwaters: lability and the d electron configuration

The kinetic speciation of Co(II), Ni(II), Cu(II), and Zn(II) in model solutions of a well-characterized fulvic acid (Laurentian fulvic acid), freshwater samples from the Rideau River (Ottawa, Ontario), and freshwater samples from the Sudbury (Ontario) area were investigated by the competing ligand exchange method using Chelex 100 as the competing ligand and by inductively coupled plasma-mass spectrometry to measure the dissociation kinetics. The metal species were quantitatively characterized by the rate coefficient for the first-order dissociation of metal complex to free metal ion. This technique can be applied to almost all elements and represents an important advance in our ability to investigate the kinetic availability of metal species in the freshwater environment. The order of the lability of the metal complexes, Co(II) > Ni(II) > Cu(II) < Zn(II), follows the reverse order of the ligand field stabilization energy with the exception of Cu(II); the behavior of Cu(II) is also due to the Jahn-Teller effect, which shortens the equatorial bonds and lengthens the axial bonds of a tetragonally distorted Cu(II)-L6 complex. This study has demonstrated a relationship between the lability of metal-DOM complexes of the 3d transition metals in freshwaters and their d electron configuration. This is the first time that the importance of the d electron configuration on the lability of metal complexes in the freshwater environment has been demonstrated. The slow complexation kinetics of both Ni(II) and Cu(II) suggestthatthe usual equilibrium assumption for freshwaters may be invalid.     

SOURCE ROCK CHARACTERIZATION BASED ON BIOLOGICAL MARKER DISTRIBUTIONS OF CRUDE OILS IN THE SOUTHERN GULF OF SUEZ, EGYPT

The depositional environment and maturity of source rocks in the southern Gulf of Suez were evaluated using biomarker and isotope data from crude oils derived from a variety of source rock types of different geological ages. Two oils families were identified and are referred to as types A and B. Type A oils are characterized by a predominance of oleanane and relatively low gammacerane concentrations, suggesting that they were derived from a terrigenous source rock with a significant input of angiosperm material inferred to occur within the marginally-mature syn-rift Lower Miocene Rudeis Shale. By contrast, type B oils are distinguished by a predominance of gammacerane and relatively low oleanane concentrations, suggesting that they were generated from mature marine carbonate source rocks inferred to occur within the Upper Cretaceous Brown Limestone and Middle Eocene Thebes Formation. Maturity parameters including the sterane isomerisation ratios C ₂₉αββ/(αββ+ααα), C₂₉ααα20S/(S+R) and TAS/(TAS+MAS), together with aromatic sulphur compound ratios (4-MDBT / I-MDBT; 4,6- / 1,4-DMDBT; 2,4–/ 1,4-DMDBT; and DBT / phenanthrenes), support the higher thermal maturity of type B oils relative to type A oils.
The biomarker variablility reflects the occurrence of two distinct source rocks in the southern Gulf of Suez and suggests that two independent petroleum systems are present here. These appear to be confined to the pre-rift (pre-Miocene) and syn-rift megasequences respectively.     

HYDROCARBON SEEPAGE GENERATION AND MIGRATION IN THE SOUTHERN GULF OF SUEZ, EGYPT: INSIGHTS FROM BIOMARKER CHARACTERISTICS AND SOURCE ROCK MODELLING

Active oil seepages in the Gebel El-Zeit area (southern Gulf of Suez, Egypt) occur in fault zones on the western flank of the East Zeit Basin. Gas chromatography-mass spectrometry indicates that these oils are rich in tricyclic terpanes and extended hopanes with few diasteranes. These characteristics are typical of oils derived from marine siliciclastic source rocks; an input of terrestrial angiosperms material is indicated by the very high oleanane index of 32.65% and the low gammacerane index of 6.28%. The molecular maturity parameter C₂₉ααα cholestane [20S/(20S+20R)] is < 0.5 indicating that these oils were generated at relatively low thermal maturities. The seepage oils resemble Miocene crude oils in the East Zeit Basin which are believed to be generated from the Lower Miocene Rudeis Shale. Burial history modelling indicates that oil generation from this unit began at around 3–4 Ma at vitrinite reflectance levels of Ro%=0.60–0.85. This implies extensive lateral and vertical migration has taken place for the generated oil to reach the surface. Alternatively, the seepage oils may be sourced by leakage from preexisting accumulations.     

The presence of K-12 ras mutations in duodenal adenocarcinomas and the absence of ras mutations in other small bowel adenocarcinomas and carcinoid tumors

BACKGROUND: Adenocarcinomas and carcinoid tumors are the most common malignant tumors of the small intestine. K-ras oncogene mutations at codon 12 are common in gastric, pancreatic, and colon carcinomas, with an incidence of 35-88%. K-ras mutations have not been extensively studied in either adenocarcinomas or carcinoid tumors of the small bowel. The purpose of this study was to determine whether ras mutations play an important role in the formation of these tumors. METHODS: Archival tissues from 28 adenocarcinomas and 22 carcinoid tumors of the small bowel were studied, along with archival tissues from 32 adenocarcinomas of the large bowel, which were used as controls. DNA from the small intestine tumors was analyzed for K-ras, H-ras, and N-ras oncogene mutations at codons 12, 13, and 61, using polymerase chain reaction and sequence specific oligonucleotide hybridization techniques. Large bowel adenocarcinomas were analyzed for K-ras mutations at codons 12 and 13. RESULTS: A point mutation of K-ras at codon 12 was detected in 4 of 28 (14.3%) of the small bowel adenocarcinomas, in 12 of 32 (37.5%) of the large bowel adenocarcinomas, and in 0 of 22 small intestine carcinoid tumors. No other K-ras, H-ras, or N-ras mutations were detected in any of the small bowel tumors. Each small intestine K-ras mutation was found in a duodenal adenocarcinoma (4 of 12 cases, 33%), whereas none occurred in 16 other jejunal or ileal adenocarcinomas. CONCLUSIONS: K-ras mutations appear to play a significant role in the pathogenesis of duodenal adenocarcinomas, but they do not appear to be important in the development of jejunal or ileal adenocarcinomas or of carcinoid tumors of the small intestine.     

A comparative study of palatal height in a Saudi and Egyptian population

The present study constitutes an attempt to compare normal traits for palatal height and width at different stages of dentition development of two ethnic groups of the Middle East. The observations were obtained from 346 randomly selected normal subjects, 188 Saudis and 158 Egyptians. The stone models were divided into three categories in both groups--primary, mixed and permanent dentitions. Palatal index values were calculated at two levels. Vernier calipers were used to measure the palatal width. Palatal depth was measured by profile Gauge by Vitrex. The results of this study demonstrate no significant difference between ethnic groups at levels 1 and 2 in relation to the palatal height, width and index. For both groups, palatal index increased significantly from the primary to mixed and permanent dentition at level 1. At level 2, palatal index and height showed decreases in measurement in the mixed dentition compared with the primary and the permanent dentitions. Subjective assessment of the palatal height correlated with palatal index. The casts were then labelled so that the shallow group had the smallest palatal index followed by the normal and the deep group had the largest palatal index. The results contribute to the information available on the development of palatal shape within two Middle Eastern populations. Knowledge of the normal range in shape can act as a baseline for studies of certain oral developmental abnormalities.     

Thiourea and N-Methylthiourea as Corrosion Inhibitors for Steel in Phosphoric Acid

Journal of Failure Analysis and Prevention - The effect of thiourea (TU) and N-methylthiourea (MTU) on the corrosion of mild steel in 0.5&nbsp;M H3PO4 was examined using potentiodynamic...     

Efficiency of mixed hybrid finite element and multipoint flux approximation methods on quadrangular grids and highly anisotropic media

The mixed hybrid finite element (MHFE) and the multipoint flux approximation (MPFA) methods are well suited for anisotropic heterogeneous domains since both are locally conservative and can handle general irregular grids. In this work, behaviours and performances of MHFE and MPFA methods are studied numerically for different heterogeneities and anisotropy factors on parallelograms and then on a more general quadrilateral grid. The superiority of MPFA in terms of accuracy and efficiency is clearly demonstrated for parallelogram grids. In the case of more general quadrilateral grids, MPFA becomes more central processing unit time consuming than MHFE. For high anisotropy factors, both methods give results with significant non‐physical oscillations. Copyright © 2008 John Wiley & Sons, Ltd.     

Influence of physico-chemical treatment on the subsequent biological process treating paper industry wastewater

The present paper presents the main results of the biodegradation study of paper industry wastewater through physico-chemical treatment. Indeed, around 60% of chemical oxygen demand (COD) removal can be achieved by electroflocculation treatment. Furthermore, a removal efficiency of the COD of almost 91% has been obtained by biological treatment, with activated amount of sludge for 24 h of culture. Concerning the physico-chemical pre-treatment of the untreated, filtered and electroflocculated rejection effluents, it has been investigated through the degradation curve of COD studies.     

Neural networks for real‐time nonlinear control of a variable geometry turbocharged diesel engine

New engines are submitted to emission standards that are becoming more and more restrictive. Diesel engines are typically equipped with variable geometry turbo‐compressor, exhaust gas recirculation system, high‐pressure common rail system and post‐treatment devices in order to meet these legislative requirements. Consequently, the control of diesel engines becomes a very difficult task involving five to 10 control variables that interact with each other and that are highly nonlinear. Until the present day, the control schemes integrated in the engine's controller are all based on static maps identified by steady‐state engine mapping. Afterward, these schemes are adjusted and calibrated in the vehicle using various control techniques in order to assure a better dynamic response of the engine under dynamic load. In this paper, we are interested in developing a mathematical optimization process that searches for the optimal control scheme under static and dynamic operating conditions. Firstly, we suggest modeling the engine and its emissions using mean value models which require limited experiments and are in good agreement with the experimental data. These models are then used in a dynamic optimization process based on the Broyden–Fletcher–Goldfarb–Shanno algorithm in order to find the optimal control scheme of the engine. The results show a reduction of the engine emissions without deteriorating its performance. Finally, we propose a practical control technique based on neural networks in order to apply these control schemes online to the engine. The results are promising. Copyright © 2007 John Wiley & Sons, Ltd.