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”

Features of the unconventional gas deposits development

This article generalizes the data on reserves and production of shale gas in different countries. It also analyzes the peculiarities of the geological structure and development of the shale gas and gas in dense rock deposits. As to the development of shale gas deposits with a net of horizontal wells with multi-stage hydraulic bed fracture, it presents the effect of the factor of the rock matrix permeability, half-length fracture and the distance between fractures on the gas recovery

Tunability of Critical Casimir Interactions by Boundary Conditions

We experimentally demonstrate that critical Casimir forces in colloidal systems can be continuously tuned by the choice of boundary conditions. The interaction potential of a colloidal particle in a mixture of water and 2,6-lutidine has been measured above a substrate with a gradient in its preferential adsorption properties for the mixture's components. We find that the interaction potentials at constant temperature but different positions relative to the gradient continuously change from attraction to repulsion. This demonstrates that critical Casimir forces respond not only to minute temperature changes but also to small changes in the surface properties.Comment: 4 figures; http://www.iop.org/EJ/article/0295-5075/88/2/26001/epl_88_2_26001.htm

Nernst effect of iron pnictide and cuprate superconductors: signatures of spin density wave and stripe order

The Nernst effect has recently proven a sensitive probe for detecting unusual normal state properties of unconventional superconductors. In particular, it may sensitively detect Fermi surface reconstructions which are connected to a charge or spin density wave (SDW) ordered state, and even fluctuating forms of such a state. Here we summarize recent results for the Nernst effect of the iron pnictide superconductor $\rm LaO_{1-x}F_xFeAs$, whose ground state evolves upon doping from an itinerant SDW to a superconducting state, and the cuprate superconductor $\rm La_{1.8-x}Eu_{0.2}Sr_xCuO_4$ which exhibits static stripe order as a ground state competing with the superconductivity. In $\rm LaO_{1-x}F_xFeAs$, the SDW order leads to a huge Nernst response, which allows to detect even fluctuating SDW precursors at superconducting doping levels where long range SDW order is suppressed. This is in contrast to the impact of stripe order on the normal state Nernst effect in $\rm La_{1.8-x}Eu_{0.2}Sr_xCuO_4$. Here, though signatures of the stripe order are detectable in the temperature dependence of the Nernst coefficient, its overall temperature dependence is very similar to that of $\rm La_{2-x}Sr_xCuO_4$, where stripe order is absent. The anomalies which are induced by the stripe order are very subtle and the enhancement of the Nernst response due to static stripe order in $\rm La_{1.8-x}Eu_{0.2}Sr_xCuO_4$ as compared to that of the pseudogap phase in $\rm La_{2-x}Sr_xCuO_4$, if any, is very small.Comment: To appear in: 'Properties and applications of thermoelectric materials - II', V. Zlatic and A. Hewson, editors, Proceedings of NATO Advanced Research Workshop, Hvar, Croatia, September 19 -25, 2011, NATO Science for Peace and Security Series B: Physics and Biophysics, (Springer Science+Business Media B.V. 2012

Normal and lateral critical Casimir forces between colloids and patterned substrates

We study the normal and lateral effective critical Casimir forces acting on a spherical colloid immersed in a critical binary solvent and close to a chemically structured substrate with alternating adsorption preference. We calculate the universal scaling function for the corresponding potential and compare our results with recent experimental data [Soyka F., Zvyagolskaya O., Hertlein C., Helden L., and Bechinger C., Phys. Rev. Lett., 101, 208301 (2008)]. The experimental potentials are properly captured by our predictions only by accounting for geometrical details of the substrate pattern for which, according to our theory, critical Casimir forces turn out to be a sensitive probe.Comment: 6 pages, 3 figure

Screening Methodology for the Efficient Pairing of Ionic Liquids and Carbonaceous Electrodes Applied to Electric Energy Storage

A model is presented that correlates the measured electric capacitance with the energy that comprises the desolvation, dissociation and adsorption energy of an ionic liquid into carbonaceous electrode (represented by single-wall carbon nanotubes). An original methodology is presented that allows for the calculation of the adsorption energy of ions in a host system that does not necessarily compensate the total charge of the adsorbed ions, leaving an overall net charge. To obtain overall negative (favorable) energies, adsorption energies need to overcome the energy cost for desolvation of the ion pair and its dissociation into individual ions. Smaller ions, such as BF4 −, generally show larger dissociation energies than anions such as PF6 − or TFSI−. Adsorption energies gradually increase with decreasing pore size of the CNT and show a maximum when the pore size is slightly greater than the dimensions of the adsorbed ion and the attractive van der Waals forces dominate the interaction. At smaller pore diameters, the adsorption energy sharply declines and becomes repulsive as a result of geometry deformations of the ion. Only for those diameters where the adsorption reaches maximum values is the adsorption energy sufficiently negative to balance the positive dissociation and desolvation energies. We present for each ion (and ionic liquid) what the most adequate electrode pore size should be for maximum capacitance

Charge transition phenomena in the heterostructure crystalline Si-Bi-amorphous film Ge₃₃As₁₂Se₅₅

Ge₃₃As₁₂Se₅₅-Si(n) heterostructures with modified by bismuth atoms transition layer were obtained by the discrete thermal evaporation method. Described are formation and investigation methods for these heterostructures. The mechanism of charge transmission in this heterostructures was ascertained. It is illustrated that the barrier for holes at the boundary is absent. The energy diagram of the heterostructure was built. Analyzed is the absence of a soft breakdown, which is caused by the electrons transfer through interstices when the negative voltage is applied. The dependence of heterostructure electrophysical properties on Ge₃₃As₁₂Se₅₅ film thickness was investigated. It is shown that in heterostructures with a modified transition layer ther is a necessity to use Ge₃₃As₁₂Se₅₅ film with the thickness more than 0.4 mm. It is ascertained that at the modification of the transition layer the conversion from the sharp to smooth transition takes place, which is caused by diffusion of bismuth atoms to surface layers

Mass transport effect and surface relief formation in AsxS100-x nanolayers

AbstractUnique structural, electronic and optical properties have determined many various applications of chalcogenide glassy (ChG) materials. The large refractive indices and third-order optical nonlinearities of the chalcogenide glasses make them the best candidates for the photonic devices to ultrafast all-optical switching and data processing.Various applications have been proposed on the basis of the light sensitivity of non-crystalline chalcogenides, especially in amorphous thin film form. Photosensitivity is a key feature of chalcogenide glasses for phasechange memory, direct waveguide and grating writing

Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides

Weak-coupling approaches to the pairing problem in the iron pnictide superconductors have predicted a wide variety of superconducting ground states. We argue here that this is due both to the inadequacy of certain approximations to the effective low-energy band structure, and to the natural near-degeneracy of different pairing channels in superconductors with many distinct Fermi surface sheets. In particular, we review attempts to construct two-orbital effective band models, the argument for their fundamental inconsistency with the symmetry of these materials, and the comparison of the dynamical susceptibilities in two- and five-orbital models. We then present results for the magnetic properties, pairing interactions, and pairing instabilities within a five-orbital Random Phase Approximation model. We discuss the robustness of these results for different dopings, interaction strengths, and variations in band structure. Within the parameter space explored, an anisotropic, sign-changing s-wave state and a d_x2-y2 state are nearly degenerate, due to the near nesting of Fermi surface sheets.Comment: 17 pages, 23 figure