Determination of the suitable drilling operating parameters in different geological formations El-Sharara Oil Field (South-Western Libya)

Purpose. The objective of this study is to determine the best operating conditions for the most notable drilling parameters (i.e. weight on bit (WOB), rotary drilling speed (RPM), and characteristics of drilling fluid) using field data obtained from El-Sharara Oil Field. Methods. The used data has been extracted from daily drilling reports of well named (NC-186/K04h) field. Such data contains information about the geological formations, casing strings, drill-bits, fuel consumption, flow rate of drilling fluid and other drilling parameters. Findings. The results reveal that, the lower geological formations of El-Sharara Oil Field, the harder are the upper formations. Therefore, it is recommended to apply heavy loads (i.e. WOB of 45000 lb) with low drilling speed (i.e. 100 rpm) in the lower formations; and to apply small loads (i.e. WOB of 19000 lb) with high drilling speed (i.e. 160 rpm) in the upper formations. Originality. This study evaluates the performance of drilling operation based on the interaction between rock formations and machine drilling parameters. Practical implications. Understanding such interaction between rock formations and machine drilling parameters will remarkably improve the rate of penetration (ROP) in the related geological formations. Consequently, the overall drilling costs will be reduced in terms of drilling time, life of drill-bit and fuel consumption.Мета. Визначення оптимальних експлуатаційних умов для технологічних параметрів буріння – осьового навантаження на долото (ОНД), швидкості обертального буріння (ШOБ), характеристик бурового розчину на основі емпіричних даних, отриманих на нафтовому родовищі Ель-Шарара. Методика. У роботі вивчені та систематизовані дані експлуатації нафтової свердловини NC-186/K04h, що містять інформацію про геологічні формації родовища, обсадних колонах, бурових коронках, витрат палива і бурової рідини та інших параметрах буріння. Результати. Дослідження показало, що, чим нижче розташовані нафтоносні геологічні формації Ель-Шарара, тим міцніше породи верхніх формацій. Рекомендовано застосовувати велике навантаження (ОНД – близько 104 кг), при низькій ШOБ (100 об/хв) у нижніх формаціях; і мале навантаження (ОНД – 86 кг) при високій ШOБ (160 об/хв) – у верхніх формаціях. Встановлено кореляційний взаємозв’язок комплексу технологічних параметрів буріння з умовами геологічних формацій родовища. Наукова новизна. Для умов нафтового родовища Ель-Шарара дана наукова оцінка ефективності буріння на основі встановлення взаємозв’язку параметрів формацій і бурових установок. Практична значимість. Врахування взаємозв’язку геологічних формацій і параметрів механічного буріння дозволить суттєво підвищити швидкість проходки свердловин, при цьому загальні витрати на буріння будуть скорочені за рахунок зменшення часу буріння, споживання палива та збільшення терміну служби бурових коронок.Цель. Определение оптимальных эксплуатационных условий для технологических параметров бурения – осевой нагрузки на долото (ОНД), скорости вращательного бурения (СВБ), характеристик бурового раствора на основе эмпирических данных, полученных на нефтяном месторождении Эль-Шарара. Методика. В работе изучены и систематизированы данные о эксплуатации нефтяной скважины NC-186/K04h, которые содержат информацию о геологических формациях месторождения, обсадных колоннах, буровых коронках, расходе топлива и буровой жидкости, а также других параметрах бурения. Результаты. Исследование показало, что, чем ниже расположены нефтеносные геологические формации Эль-Шарара, тем тверже породы верхних формаций. Рекомендуется применять большую нагрузку (ОНД – около 104 кг), при низкой СВБ (100 вр/мин) в нижних формациях; и малую нагрузку (ОНД – 86 кг) при высокой СВБ (160 вр/мин) – в верхних формациях. Установлена корреляционная взаимосвязь комплекса технологических параметров бурения с условиями геологических формаций месторождения. Научная новизна. Для условий нефтяного месторождения Эль-Шарара дана научная оценка эффективности бурения на основе установления взаимосвязи параметров формаций и буровых установок. Практическая значимость. Учет взаимосвязи геологических формаций и параметров механического бурения позволит существенно увеличить скорость проходки скважин, при этом общие затраты на бурение будут сокращены за счет уменьшения времени бурения, потребления топлива и увеличения срока службы буровых коронок.The authors declare that the paper has not been originated under any project and no funding has been raised for this research

Optička svojstva soli polianilina i baze polianilina punjenog s KBr, Co(CH3COO)2 i pikričnom kiselinom

Polyaniline was prepared by chemical methods. The composites were prepared by the hot pressing of polyaniline base with different percentages of KBr, Co(CH3COO)2 and picric acid. The diffused reflectance of polyaniline doped with 10, 15, 25 and 50 wt% of KBr, picric acid and cobalt acetate, was measured at room temperature in the wavelength range from 500 to 1800 nm. The energy gaps of the samples were then deduced as well as the position and number of the indirect transitions which were found to be dependent on the concentration percentage of the doping materials. The energy gaps of all samples decrease by increasing the concentration percentage of the doping materials.Polianilin smo pripremili kemijskim postupkom. Mješavine smo postigli vrućim tiskanjem polianilina s raznim postocima KBr, Co(CH3COO)2 i pikrične kiseline. Mjerili smo difuznu reflektanciju polianilina s 10, 15, 25 and 50 tež% KBr, pikrične kiseline i kobaltnog acetata na sobnoj temperaturi za valne duljine 500 do 1800 nm. Odredili smo energijske procjepe te položaje i broj posrednih prijelaza. Ustanovili smo za sve uzorke pad energijskih procjepa pri povećanju koncentracije dodataka

Optička svojstva soli polianilina i baze polianilina punjenog s KBr, Co(CH3COO)2 i pikričnom kiselinom

Polyaniline was prepared by chemical methods. The composites were prepared by the hot pressing of polyaniline base with different percentages of KBr, Co(CH3COO)2 and picric acid. The diffused reflectance of polyaniline doped with 10, 15, 25 and 50 wt% of KBr, picric acid and cobalt acetate, was measured at room temperature in the wavelength range from 500 to 1800 nm. The energy gaps of the samples were then deduced as well as the position and number of the indirect transitions which were found to be dependent on the concentration percentage of the doping materials. The energy gaps of all samples decrease by increasing the concentration percentage of the doping materials.Polianilin smo pripremili kemijskim postupkom. Mješavine smo postigli vrućim tiskanjem polianilina s raznim postocima KBr, Co(CH3COO)2 i pikrične kiseline. Mjerili smo difuznu reflektanciju polianilina s 10, 15, 25 and 50 tež% KBr, pikrične kiseline i kobaltnog acetata na sobnoj temperaturi za valne duljine 500 do 1800 nm. Odredili smo energijske procjepe te položaje i broj posrednih prijelaza. Ustanovili smo za sve uzorke pad energijskih procjepa pri povećanju koncentracije dodataka

Oncogenic osteomalacia: A case report and review of the literarture

Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by severe hypophosphoremia due to renal phosphate wasting and osteomalacia clinically near to hereditary hypophosphoremic rickets. This disorder is induced by a benign tumor which belongs to the group of « phosphaturic mesenchymal tumor mixed connective tissue variant » secreting phosphaturic factors. We report the case of a 54-year old man who presented with diffuse bone pain and bilateral hip pain evolving for 3 years. Physical examination revealed a subcutaneous tumor of the leftflank. A radiographic skeletal survey showed signs of osteomalacia with an overall « washed-out » appearance of the bone, cuneiform aspect of dorsolombar vertebral bodies and bilateral fracture of femoral necks. Serum Fibroblast Growth Factor 23 concentration was high. The patient had total bilateral hips arthroplasty and surgical removal of the tumor of the flank was performed. There was rapid improvement and the laboratory values returned to normal.Keywords: Oncogenic, Osteomalacia, Mesenchymal, Tumor, fibroblast growth factor

Monotonic Positive Solutions of Nonlocal Boundary Value Problems for a Second-Order Functional Differential Equation

We study the existence of at least one monotonic positive solution for the nonlocal boundary value problem of the second-order functional differential equation x′′(t)=f(t,x(ϕ(t))), t∈(0,1), with the nonlocal condition ∑k=1makx(τk)=x0, x′(0)+∑j=1nbjx′(ηj)=x1, where τk∈(a,d)⊂(0,1), ηj∈(c,e)⊂(0,1), and x0,x1>0. As an application the integral and the nonlocal conditions ∫adx(t)dt=x0, x′(0)+x(e)-x(c)=x1 will be considered

Effect of subchronic intake of green tea extract on liver of albino rat histomorphometric, ultrastructural and biochemical study

Background: There are conflicting reports on the effect of green tea extract (GTE) on the liver of animals. Some studies failed to show any adverse hepatic effects following administration of GTE to mice, rats, and dogs. Others reported severe hepatic necrosis, resulting in death in female Swiss-Webster mice following its administration. The aim of the study was to examine the subchronic toxicity of GTE on the liver of the adult male albino rats. Materials and methods: Forty male adult Wistar albino rats were used in the study. The rats were divided into four groups; group I (control), group II (low-dose green tea), group III (medium-dose green tea) and group IV (high-dose green tea). Histological, biochemical and histomorphometric analyses were done. Results: Mild hepatic affections were observed in group II. The affections were severe in groups III and IV. The central veins and hepatic sinusoids were congested. The hepatocytes were degenerated. Hypertrophy of the hepatic arteries, dilation of the bile ducts and cellular infiltration were clearly observed in the last two groups. Mild degenerative changes were observed in the hepatocytes in rat’s group II; the cytoplasm was rarefied and vacuolated. Some mitochondria were ruptured. The blood sinusoids were congested. The rough endoplasmic retinaculum was fragmented in group III. More degenerative changes were observed in group IV; the hepatic architectures were lost with disruption of cell membranes. Most of the cell organelles were degenerated and most of mitochondria were ballooned. As compared to that of the control groups: the total serum protein values in groups II, III and IV showed a statistically significant decrease (12%, 20% and 21%, respectively), the mean area per cent of collagen fibres in groups III and IV increased 5 and 7 folds. Conclusions: Subchronic administration of GTE resulted in structural and functional affection of the rats’ liver. The dose of 250 mg/kg/day seemed to be safe, while the doses of 500 mg/kg/day and 1000 mg/kg/day had deleterious effect being more evident in the latter dose

Computational assessment of ballistic impact on a high strength structural steel/polyurea composite plate

Ballistic impact on a polyurea retrofitted high strength structural steel plate is simulated and validated. A soft material model for polyurea, which is capable of capturing complex mechanical behavior characterized by large strains, hysteresis, rate sensitivity, stress softening (Mullins effect), and deviatoric and volumetric plasticity, is calibrated against several uniaxial tension experiments and a threedimensional release wave experiment to capture both the material point and bulk behaviors. A porous plasticity model is employed to model the high strength structural steel and localization elements are included to capture adiabatic shear bands and strain localization. The computational capabilities of these models are demonstrated by the prediction of the target plate displacement, which shows excellent agreement with experiments

Role of hydrogen in volatile behaviour of defects in SiO2-based electronic devices

Charge capture and emission by point defects in gate oxides of metal–oxide–semiconductor field-effect transistors (MOSFETs) strongly affect reliability and performance of electronic devices. Recent advances in experimental techniques used for probing defect properties have led to new insights into their characteristics. In particular, these experimental data show a repeated dis- and reappearance (the so-called volatility) of the defect-related signals. We use multiscale modelling to explain the charge capture and emission as well as defect volatility in amorphous SiO2 gate dielectrics. We first briefly discuss the recent experimental results and use a multiphonon charge capture model to describe the charge-trapping behaviour of defects in silicon-based MOSFETs. We then link this model to ab initio calculations that investigate the three most promising defect candidates. Statistical distributions of defect characteristics obtained from ab initio calculations in amorphous SiO2 are compared with the experimentally measured statistical properties of charge traps. This allows us to suggest an atomistic mechanism to explain the experimentally observed volatile behaviour of defects. We conclude that the hydroxyl-E′ centre is a promising candidate to explain all the observed features, including defect volatility