On stability of collisional coupling between relativistic electrons and ions in hot plasmas

The collisional coupling of relativistic electrons and non-relativistic ions in hot plasmas has been analysed. It is found that relativistic effects produce a new feature: while the condition T_e<3T_i guarantees a stable collisional coupling between electrons and ions in low-temperature plasmas, relativistic effects shift the upper T_e/T_i boundary of stability to higher values. Moreover, for sufficiently high temperatures, T_{e,i} > 75 keV, collisional decoupling between relativistic electrons and ions becomes impossible

Relativistic neoclassical radial fluxes in the 1/nu regime

The radial neoclassical fluxes of electrons in the 1/nu regime are calculated with relativistic effects taken into account and compared with those in the non-relativistic approach. The treatment is based on the relativistic drift-kinetic equation with the thermodynamic equilibrium given by the relativistic Maxwell-J\"uttner distribution function. It is found that for the range of fusion temperatures, T_e<100 keV, the relativistic effects produce a reduction of the radial fluxes which does not exceed 10%. This rather small effect is a consequence of the non-monotonic temperature dependence of the relativistic correction caused by two counteracting factors: a reduction of the contribution from the bulk and a significant broadening with the temperature growth of the energy range of electrons contributing to transport. The relativistic formulation for the radial fluxes given in this paper is expressed in terms of a set of relativistic thermodynamic forces which is not identical to the canonical set since it contains an additional relativistic correction term dependent on the temperature. At the same time, this formulation allows application of the non-relativistic solvers currently used for calculation of mono-energetic transport coefficients.Comment: 10 pages, 2 figure

Relativistic neoclassical fluxes in hot plasmas

The radial fluxes of particles and energy with relativistic effects taken into account are represented in a form standard for neoclassical theory. All the formulations are based on the relativistic equations of motion and the relativistic drift-kinetic equation. As an illustration of the influence of relativistic effects, the radial neoclassical fluxes of electrons in 1/ν collisional regime are calculated and compared with those in the classical approach. The proposed formulation allows one to implement the relativistic effects in current transport codes.Радиальные потоки частиц и энергии, включающие релятивистские эффекты, представлены в форме, стандартной для неоклассической теории. Все формулировки основаны на релятивистских уравнениях движения и релятивистском дрейфово-кинетическом уравнении. В качестве иллюстрации влияния релятивистских эффектов на процессы переноса в плазме предлагается сравнительная оценка релятивистских и нерелятивистских радиальных неоклассических потоков электронов, посчитанных для стеллараторного режима 1/ν. Предложенная формулировка позволяет включить релятивистские эффекты в существующие транспортные коды.Радіальні потоки частинок та енергії, що ураховують релятивістські ефекти, запропоновано у формі, яка є стандартною для неокласичної теорії. Усі формулювання базуються на релятивістських рівняннях руху та релятивістському дрейфово-кінетичному рівнянні. В якості ілюстрації впливу релятивістських ефектів на процеси переносу в плазмі запропоновано порівняння релятивістських та нерелятивістських радіальних неокласичних потоків електронів, разрахованих для стелараторного режиму 1/ν. Запропоноване формулювання дозволяє ураховувати релятивістські ефекти в існуючих транспортних кодах

Efficiency Evaluation Of Implementation Of Optimization Methods Of Operation Modes Of The "Plast - Gas Pipeline" System By The Methods Of Mathematical Modeling

To date, Ukraine's mature gas fields, which are being developed in the gas regime, are at the final stage of development, which is characterized by a significant depletion of reservoir energy. The final stage of development requires solving complex problems related to watering wells, destruction of the reservoir, removal of formation water and mechanical impurities, increasing back pressure in the system, as well as the moral and physical wear and tear of industrial equipment. In the conditions of falling gas production, a significant part of the operating well stock is unstable, in the mode of unauthorized stops due to the accumulation of liquid at the bottom and insufficient gas velocities for removal to the surface, and also the accumulation of the liquid phase in the lowered places of the gas gathering system.Within the framework of the conducted studies, the gas dynamic models of the operation of the gas collection system of 3 oil/gas-condensate fields (OGCF) are created. A single model of the gas production system "reservoir - well - gas gathering system - inter-field gas pipeline - main facilities" is built. The current efficiency of the gas production, collection and transportation system is assessed. On the basis of model calculations, the current production capabilities of the wells are defined, as well as the "narrow" places of the system.It is established that the introduction of modern technologies for the operation of watered wells without optimizing the operation of the entire gas production system is irrational, since the liquid that is carried out from the wellbore will accumulate in the plumes and increase the back pressure level in the ground part. In conditions of increasing gas sampling, liquid flowlines can be taken out of the loops and deactivated the separation equipment.The feasibility of introducing methods for optimizing the operation modes of the gas production - gathering and transportation system is estimated, which allows choosing the optimal method for increasing the efficiency and reliability of its operation.For the first time in the Ukrainian gas industry, an integrated model of the field is created as a single chain of extraction, collection, preparation and transportation of natural gas, which can be adapted for the development and arrangement of both new and mature deposits.The main advantage of the application for the hydrocarbon production sector is the simulation of the processes, which makes it possible to evaluate the operating mode of the well in the safe zone while reducing the working pressure and introducing various intensification methods, and also to estimate the increase in hydrocarbon production. For the equipment of the ground infrastructure – "midstream" – the main advantage is a reduction in the time required to perform design calculations for gas pipelines, trains and pipelines for transporting multiphase media using public models.The creation and use of integrated models of gas fields gives an understanding of the integral picture of available resources and ensures an increase in the efficiency of field development management.The results of the calculation are clearly correlated with the actual data, which makes it possible to use the models constructed to obtain numerical results