Analysis of possibilities to increase oil recovery with the use of nitrogen in the context of deep oil deposits of the Dnipro-Donetsk oil-and-gas Ukrainian province

Purpose is to increase oil recovery of deep oil deposits of the Dnipro-Donetsk oil-and-gas Ukrainian province with the use of nitrogen. Methods. Experiments, intended to residual oil displacement with the use of different driving agents, involved laboratory modeling of the process when a seam was simulated as such being close maximally to a real seam and samples of formation fluids were applied. The experiments, which materialized equilibrium displacement (without mass transfer), used seam models developed from cores of V-19n seam (Perekopivske deposit). 43 core samples were analyzed with 3.3 – 226.0·10-3 µm2 permeability. Findings. Characteristics and applicability of nitrogen and flue gas to increase oil recovery have been analyzed. Theoretic prerequisites of the mechanism, aimed at oil displacement using nitrogen and flue gases, have been formulated. Results of the laboratory experiments of oil displacement by means of nitrogen within a porous environment have helped determine that minimum pressure of mutual oil and nitrogen dissolution is 36.0 – 38.0 MPa. In terms of mutual mixing of agents at 110 – 112°С temperature, 36.4 МPа gas injection pressure, and nitrogen pumping velocity being 1 cm3 per 40 minutes, oil displacement ratio achieved 0.76 – 0.78. Originality. For the first time, parameters of mixable oil displacement using nitrogen for the conditions of deep oil deposits of the Dnipro-Donetsk petroleum province in Ukraine have been determined. Efficiency of mixable nitrogen displacement to compare with water displacement and nitrogen displacement under equilibrium conditions has been proved. Practical implications. The advanced technique of nitrogen use to improve oil recovery in the context of deep oil deposits has been proposed. The technique is applicable to extract residual oil from the depleted deposits.Мета. Підвищення нафтовилучення глибоких нафтових родовищ Дніпровсько-Донецької нафтогазоносної провінції України з використанням азоту. Методика. Експериментальні дослідження витіснення залишкової нафти різними витіснювальними агентами проводили шляхом лабораторного моделювання процесу зі створенням зразків пласта, максимально наближених до реального пласту, і використанням зразків пластових флюїдів. В експериментах, в яких реалізувалося рівноважне витіснення (без масопереносу), використовувалися моделі пласта, які споруджувалися з кернового матеріалу пласта В-19н Перекоповського родовища. Було досліджено 43 зразки керна, проникність сягала в межах 3.3 – 226.0·10-3 мкм2. Результати. Проаналізовано особливості та умови застосування азоту й димових газів для підвищення нафтовіддачі пластів. Сформульовано теоретичні передумови механізму витіснення нафти з пласта азотом і димовими газами. Встановлено за результатами лабораторних досліджень витіснення нафти азотом у пористому середовищі мінімальний тиск взаємного розчинення нафти та азоту, котрий становить 36.0 – 38.0 МПа. В умовах взаємного змішування агентів при температурі 110 – 112°С, тиску нагнітання газу 36.4 МПа і швидкості нагнітання азоту 1 см3 за 40 хвилин коефіцієнт витіснення нафти досягав величини 0.76 – 0.78. Наукова новизна. Вперше встановлені параметри змішуваного витіснення нафти азотом для умов глибоких нафтових родовищ Дніпровсько-Донецької нафтогазоносної провінції України. Доведено високу ефективність змішуваного витіснення азотом в порівнянні з витісненням водою і витісненням азотом при рівноважних умовах. Практична значимість. Запропоновано удосконалену технологію використання азоту для підвищення нафтовилучення глибоких нафтових родовищ, яка може бути використана для виснажених нафтових родовищ.Цель. Увеличение нефтеотдачи глубокозалегающих нефтяных месторождений Днепровско-Донецкой нефтегазоносной провинции Украины с использованием азота. Методика. Экспериментальные исследования вытеснения остаточной нефти разными вытесняющими агентами проводили путем лабораторного моделирования процесса с созданием образцов пласта, максимально приближенных к реальному пласту, и использованием образцов пластовых флюидов. В экспериментах, в которых реализовалось равновесное вытеснение (без масопереноса), использовались модели пласта, которые сооружались из кернового материала пласта В-19н Перекоповского месторождения. Были исследованы 43 образца керна, проницаемость находилась в пределах 3.3 – 226.0·10-3 мкм2. Результаты. Проанализированы особенности и условия применения азота и дымовых газов для повышения нефтеотдачи пластов. Сформулированы теоретические предпосылки механизма вытеснения нефти из пласта азотом и дымовыми газами. Установлено по результатам лабораторных исследований вытеснения нефти азотом в пористой среде минимальное давление взаимного растворения нефти и азота, которое составляет 36.0 – 38.0 МПа. В условиях взаимного смешивания агентов при температуре 110 – 112°С, давлении нагнетания газа 36.4 МПа и скорости нагнетания азота 1 см3 за 40 минут коэффициент вытеснения нефти достигал величины 0.76 – 0.78. Научная новизна. Впервые установлены параметры смешиваемого вытеснения нефти азотом для условий глубокозалегающих нефтяных месторождений Днепровско-Донецкой нефтегазоносной провинции Украины. Доказана высокая эффективность смешиваемого вытеснения азотом по сравнению с вытеснением водой и вытеснением азотом при равновесных условиях. Практическая значимость. Предложена усовершенствованная технология использования азота для повышения нефтеотдачи глубокозалегающих нефтяных месторождений, которая может быть использована для истощенных нефтяных месторождений.The research results have been obtained with no support in the form of grants of projects. The authors express thanks to PJSC “Ukrnafta” for the possibility to carry out the experiments, which findings are represented by the paper, on the basis of Scientific-Research and Design Institute PJSC “Ukrnafta”

Untersuchungen zur Funktion der Exodermis von Gerstenwurzeln (Hordeum vulgare L. cv. Alexis) im Hinblick auf den radialen Transport anorganischer Ionen im Apoplasten

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Advanced flamelet tabulation strategies for Large Eddy Simulations of single- and multi-phase turbulent jet flames

The constantly increasing demands placed on modern combustion processes in terms of efficiency and pollutant reduction make it necessary to optimize existing combustion processes, develop new ones and use alternative fuels. Numerical simulations help to develop and understand these processes. One efficient combustion modeling methodology is the pre-tabulation of flame structures. For the simulation of non-premixed flames, the so-called Flamelet-Progress-Variable (FPV) approach has been established. This involves the flame structure, which is not resolved in 3D CFD, being modeled using one-dimensional diffusion flames with different strain rates. The progress variable is used as a reactive scalar to describe the reaction progress of these structures. This approach, in combination with the Large Eddy Simulation (LES) of the turbulent flow typically occurring in technical systems, provides very good results for many fields of application. However, the pre-assumption of flame structures implies modeling assumptions that have to be constantly verified for new applications. For example, it is known how differential diffusion along the flame structure can be modeled. However, the damping of differential diffusion due to turbulent structures must be directly specified when modeling the diffusion within the flame structures. Thus, flames which are strongly influenced by differential diffusion and flames where that influence is not relevant can be modeled well. Experimental data from a non-premixed oxy-fuel jet flame with hydrogen admixture have shown, however, that the effect of differential diffusion can vary locally and for individual species. The first part of the present dissertation examines how suitable modern modeling approaches are for representing this effect. Existing diffusion modeling approaches describing the flame structure with different levels of complexity are systematically compared. The complexity of the resulting flame structure makes it necessary to develop a suitable table parameterization, which is presented in this dissertation. The different approaches are compared in a prior analysis of the flame structure and in coupled LES with experimental Raman/Rayleigh data. In this process, the potential of the individual modeling approaches is elaborated. The identified limitations indicate the need for further research in this area. Another technical field in which the tabulation of flame structures has become established itself as a valid approach is high-pressure spray combustion, which is relevant for diesel engines. The challenge in this area is to map the multitude of processes occurring during the usually two-stage ignition process up to the formation of pollutants. The tabulation of igniting transient diffusion flames (Unsteady Flamelet Progress Variable Approach, UFPV) provides very good results in a large number of studies. The modeling approaches found in the literature employ a wide range of strain rates. However, the model quality is often very similar with respect to global combustion characteristics. The present dissertation contributes in this respect within the framework of a systematic discussion of the influence of different strain rates in spray simulation. The single-hole injector Spray A defined in the Engine Combustion Network is used as a reference case. This dissertation shows that the strain rate significantly delays the ignition upstream of the flame lift-off length. Moreover, local extinction during ignition is identified for this case. However, its probability is comparatively low. In addition to ignition, the formation of pollutants in these spray flames is a problem of high technical relevance. The challenge here is to formulate the progress variables for the strongly differing time scales of ignition and the slow development of pollutant species such as nitrogen oxides and soot precursors. The present dissertation complements the approaches known in the literature by adding a new progress variable definition. This definition consists of two progress variables, which describe individual processes of ignition and pollutant formation. Their normalized value is added to obtain the progress variable used for the parameterization of the look-up table. The approach is therefore referred to as the Unsteady Flamelet Composed Progress Variable (UFCPV) approach in this dissertation. This approach is verified in a one-dimensional test case with respect to the representation of ignition, combustion and pollutant formation under conditions relevant to the diesel engine. Comparison with the original definition shows the improvement of the approach. The validation of the approach in the 3D simulation is again performed using ECN Spray A. For validation purpose, 355-nm PLIF data and recently published 355-nm high-speed PLIF data are used. These allow a detailed comparison of the spatially and temporally resolved structure of formaldehyde and soot precursors. Here, the simulation shows very good agreement with the experimental data. The validated model is also used to analyze experimentally obtained statements concerning the separation of the above-mentioned species and its dynamic detachment behavior for the first time in a numerical study and to relate them to periodic fluctuations of the mixture fraction field. Its application to the ECN Spray D also serves to investigate the suitability of the model when the nozzle hole diameter is varied. Here, an underestimation of the ignition delay time is found. However, it can be shown from comparison with so far unpublished 355-nm high-speed PLIF data that the resulting flame structure is well reproduced by the experimentally determined morphology when this time offset is included. This suggests that although chemical reactions are initiated too early, the resulting flame structure is valid. The validated model allows the development of a comprehensive overview of the structure of the spray flame, including all relevant variables along the cause-effect chain from injection to gaseous pollutant formation. This is presented for the ECN Spray A and the ECN Spray D

Off-season biogenic volatile organic compound emissions from heath mesocosms: responses to vegetation cutting

Biogenic volatile organic compounds (BVOCs) affect both atmospheric processes and ecological interactions. Our primary aim was to differentiate between BVOC emissions from above- and belowground plant parts and heath soil outside the growing season. The second aim was to assess emissions from herbivory, mimicked by cutting the plants. Mesocosms from a temperate Deschampsia flexuosa-dominated heath ecosystem and a subarctic mixed heath ecosystem were either left intact, the aboveground vegetation was cut, or all plant parts (including roots) were removed. For 3–5 weeks, BVOC emissions were measured in growth chambers by an enclosure method using gas chromatography-mass spectrometry. CO(2) exchange, soil microbial biomass, and soil carbon and nitrogen concentrations were also analyzed. Vegetation cutting increased BVOC emissions by more than 20-fold, and the induced compounds were mainly eight-carbon compounds and sesquiterpenes. In the Deschampsia heath, the overall low BVOC emissions originated mainly from soil. In the mixed heath, root, and soil emissions were negligible. Net BVOC emissions from roots and soil of these well-drained heaths do not significantly contribute to ecosystem emissions, at least outside the growing season. If insect outbreaks become more frequent with climate change, ecosystem BVOC emissions will periodically increase due to herbivory

Reduction of energy input in wire arc additive manufacturing (WAAM) with gas metal arc welding (GMAW)

Wire arc additive manufacturing (WAAM) by gas metal arc welding (GMAW) is a suitable option for the production of large volume metal parts. The main challenge is the high and periodic heat input of the arc on the generated layers, which directly affects geometrical features of the layers such as height and width as well as metallurgical properties such as grain size, solidification or material hardness. Therefore, processing with reduced energy input is necessary. This can be implemented with short arc welding regimes and respectively energy reduced welding processes. A highly efficient strategy for further energy reduction is the adjustment of contact tube to work piece distance (CTWD) during the welding process. Based on the current controlled GMAW process an increase of CTWD leads to a reduction of the welding current due to increased resistivity in the extended electrode and constant voltage of the power source. This study shows the results of systematically adjusted CTWD duringWAAM of low-alloyed steel. Thereby, an energy reduction of up to 40% could be implemented leading to an adaptation of geometrical and microstructural features of additively manufactured work pieces

Inert Drying System for Copper Paste Application in PV

AbstractIn this study we show that the electrical characteristics of low temperature polymer pastes are improved by carrying out the curing process in an inert nitrogen atmosphere. In order to reduce the solar cell production costs, numerous scientific works are devoted to the question, whether the commonly used silver paste can be replaced by a copper based paste. However, a major problem with the latter is, that copper tends to oxidate during the thermal treatment. Hence, this work focuses on the development of an inert inline drying system to avoid the oxidation of copper based polymer pastes. For reference, silver based polymer pastes are investigated simultaneously. Therefore the influence of different nitrogen curing atmospheres on the electrical resistance and the weight loss of the pastes is evaluated. The electrical resistance of both silver and copper based pastes is improved by reducing the residual oxygen concentration. To investigate the reason for this, the samples are analyzed by micrographics. Furthermore it is shown, that the weight loss of the pastes shows no dependence on the curing atmosphere

Wire arc additive manufacturing (WAAM) of aluminium alloy AlMg5Mn with energy-reduced gas metal arc welding (GMAW)

Large-scale aluminum parts are used in aerospace and automotive industries, due to excellent strength, light weight, and the good corrosion resistance of the material. Additive manufacturing processes enable both cost and time savings in the context of component manufacturing. Thereby, wire arc additive manufacturing (WAAM) is particularly suitable for the production of large volume parts due to deposition rates in the range of kilograms per hour. Challenges during the manufacturing process of aluminum alloys, such as porosity or poor mechanical properties, can be overcome by using arc technologies with adaptable energy input. In this study, WAAM of AlMg5Mn alloy was systematically investigated by using the gas metal arc welding (GMAW) process. Herein, correlations between the energy input and the resulting temperature–time-regimes show the effect on resulting microstructure, weld seam irregularities and the mechanical properties of additively manufactured aluminum parts. Therefore, multilayer walls were built layer wise using the cold metal transfer (CMT) process including conventional CMT, CMT advanced and CMT pulse advanced arc modes. These processing strategies were analyzed by means of energy input, whereby the geometrical features of the layers could be controlled as well as the porosity to area portion to below 1% in the WAAM parts. Furthermore, the investigations show the that mechanical properties like tensile strength and material hardness can be adapted throughout the energy input per unit length significantl

Einfluss der maschinellen Autotransfusion auf die Notwendigkeit der Fremdblut-Transfusion bei elektiver primärer Hüft- oder Knie-Endoprothetik

Zielsetzung: Die maschinelle Autotransfusion ist ein Verfahren, mit welchem intra- und unmittelbar postoperativ Wundblut gesammelt und dem Patienten retransfundiert werden kann. Mit der hier vorgelegten Untersuchung sollte die Frage geklärt werden, ob durch die Verwendung einer MAT die Häufigkeit einer Fremdbluttransfusion bei primären Hüft- und Knie-TEP-Operationen reduziert werden kann. Methode: Im Rahmen der Untersuchung wurden 379 konsekutive Patienten, welche sich einer einseitigen Primär-Endoprothesenimplantation am Knie- oder Hüftgelenk unterzogen, und die zum Zeitpunkt der Operation keine gerinnungshemmenden Medikamente einnahmen, prospektiv randomisiert je einer Therapiegruppe mit MAT bzw. je einer Kontrollgruppe ohne MAT zugeordnet. Gemessen wurde neben den postoperativen Hb-Konzentrationen die Dauer des Krankenhausaufenthaltes, auftretende Komplikationen, das Volumen von notwendigen Fremd-Ek-Transfusionen sowie der Hb-Wert vor und nach Transfusion, das Volumen des Retransfundates des aufbereiteten Wundblutes sowie der Hämatokrit – sofern eine Wiederaufbereitung erfolgte. Ergebnis: Unsere Untersuchung zeigte keinen Vorteil der MAT im Hinblick auf die postoperativen Hb-Werte der Patienten oder die Reduktion der Transfusionshäufigkeit für allogene Ek. Die Häufigkeit von operativen Revisionen und die Krankenhausverweildauer wurden ebenfalls nicht positiv beeinflusst. Schlussfolgerung: Die MAT führt bei einseitiger Primärimplantation einer Hüft- oder Knie-Totalendoprothese nicht zu einer Reduktion der Transfusionshäufigkeit für allogene Ek. Inwieweit die MAT in Verbindung mit anderen fremdblutsparenden Maßnahmen in der Lage ist, bei den von uns untersuchten Eingriffen den Bedarf an Fremd-Ek zu reduzieren, müssen weitere Studien zeigen