Gazovaya promyshlennost’ № 02 2020

The article analyzes the prospects of water transport delivery of liquefied natural gas to remote regions of Russia for autonomous gasification of those settlements where pipeline transportation is unfeasible. The paper provides the results of forecast for liquefied natural gas consumption by regions. The main transport routes along the main Siberian rivers (Lena, Yenisei, Ob) and their large navigable tributaries, as well as those settlements located on the Arctic Ocean coast, are examined in detail. Gasification plans by 2032 are analyzed for Northern regions. The study results in the identification of promising settlements for autonomous gasification, particularly those in Yamalo-Nenets Autonomous Okrug, on the coasts of the Taz Estuary and the Gulf of Ob, as well as in Northern and Northwestern regions of Krasnoyarsk Krai. The largest ones are the towns Dudinka, Yeniseysk, and Lesosibirsk. Gasification using river transport in Northern and riverine regions of Yakutia can be seen as feasible after the commissioning of the gas processing plant in Lensk town. The total forecast LNG consumption for energy supply to the inaccessible regions of Russia is estimated at 222,028 mln tons per year.

The current state of natural gas fields is characterized by production decline and complicated operating conditions. These issues are particularly associated with wellhead pressure drop compared to the pressure in the system for gathering and treatment of well products, as well as with large water inflow. Some issues can be resolved using wellhead gas-jet devices that make it possible to extend the artificial blow-out by reducing the wellhead backpressure. A simultaneous increase in well product flow rate ensures the effective production of bottom-hole water. It is proposed to utilize gas from a neighboring well (with higher wellhead pressure) or formation pressure maintenance system as the working flow in the pump. The study aims to research the effectiveness of the gas-jet device and its optimal design concerning the tasks in hand. The paper presents the results of an integrated experimental study of the performance of gas-jet devices with diaphragm and convergent-divergent nozzles for gas pumping by the high-pressure gas flow. Empirical results have revealed that the optimal design of a gas-jet device for each type of nozzles is with a cylindrical mixing chamber.

Implementation of electromagnetic flaw detection in the Middle East has necessitated the development of theoretical foundations and result interpreting technique, as well as designing instrumentation to control the conditions of multistring wells cased by large diameter pipes. Transient electromagnetic flaw detection is the most effective way of examining multiple-string wells for the following reasons. First of all, the transient field is measured after the current is turned off, so that there is no primary field, which makes it possible to reduce the space between the coils to zero, i.e., combine the exciter and measuring coils. This significantly improves the vertical performance of the probe and allows to detect even small defects. Secondly, it is considerably easier to separate the response from the first (inner), second, third, and subsequent pipes in transient mode rather than in harmonic mode, which helps to measure the pipe wall thickness more accurately and associate the local defects correctly to a specific string. Сreating an electromagnetic field in four-string well cased by large diameter pipes requires quite long probes, approximately equal to the last string diameter, which reduces the vertical resolution. However, the resolution can be improved by using multi-probe systems for first and second strings as they can be examined with shorter probes. Based on mathematical and physical modeling, the paper identifies the optimal parameters and number of probes, as well as frequency characteristics of multistring well program examining device. Assessment of a pipe wall thickness is based on constructing a theoretical transient process decline curve that, in set metric, matches with actual data obtained for a specific point and with relevant pipe model with set parameters. Examples are provided for assessment of technical conditions of multistring wells cased by large diameter pipes.

The energy efficiency of technological processes is one of the fundamental elements of a company’s success and competitive ability. Improving this indicator has not only a positive effect on economic capacity but also reduces the environmental impacts of industrial processes. In this regard, developing of the new equipment that meets current requirements in energy efficiency and operating reliability appears to be particularly relevant. Air cooling units used in compressor stations were designed and fabricated to handle a specific process task. At the moment, they are obsolete and worn-out: operation and maintenance costs for such equipment are unjustifiably high. Based on the above, our team has formulated and implemented a concept of an advanced air cooling unit. During the development, contemporary design software was used, which significantly reduced the time needed to develop the prototype and to ensure its good performance. At the design stage, special attention was given to the advanced materials and technologies. This approach has completely justified the effort and cost invested in equipment design: the product is competitive and has good performance indicators. Pilot operation of one of the promising prototypes of air cooling unit (Turbo by Hydroaerocenter Group and ZAO Gazkholodtekhnika) in Gazprom transgaz Moscow LLC has proved that using the advance coolers enables gas transport in stable thermal mode within a wide range of flow rate.

Construction is one of the essential branches of the national economy, that facilitates the development of Russian infrastructure. The specific character of this industry arises from the large variety of engineering-production processes, frequently changing staff, high rate of manual work, a large number of technologies used and their continuous improvement, high operating speed of state-of-the-art machinery and mechanisms, complexity and high occupation hazards of their maintenance. All of this causes potentially high risks of injuries and accidents, which is confirmed by statistics: the number of registered incidents is several times higher in construction companies than in other industrial sectors. This causes a substantial material, image, and social damage to the person, the society, and the state. Preliminary estimates suggest that this damage far exceeds the expenses for preventive measures. This state of affairs has much to do with the anthropogenic factor: the staff lacks knowledge and skills necessary for safe working, and their psychophysiological characteristics are inconsistent with the conditions and nature of the work. Thus, the qualification and personal and business qualities of the person ultimately shape the reliability of the executive chain of an engineering-production process in a construction company. The article analyses the significance of the effect that staff training has on the safety index of the works in construction companies. The paper describes the ways to enhance the safety of construction and assembly works by improving the occupational health and safety training methodology. Those ways were developed and implemented by AO NIPIGAZ during the construction Amur Gas Processing Plant.

Prevention of pipeline destruction is an essential task in gas industry companies. Climate pattern in locations where the main gas pipelines of Gazprom transgaz Tchaikovsky LLC are laid, have specific effects on the underground pipeline systems and thus cause high stress corrosion (corrosion cracking under stress) damage rate of pipe elements metal. Smart pigging of the main gas pipelines shows sufficient efficiency for technical evaluation. However, pipeline pigs leave a considerable pipeline length unchecked. Such sections include compressor station pipelines, process cross-sections, and junction point systems. The acoustic emission testing adapted for pipeline inspection makes it possible to examine the whole facility, including areas difficult to reach by other techniques. This technique is based on detecting elastic vibrations caused by material deformation under stress. The additional advantage of the technique is that it does not only identify but also classifies the evolving defects by their risk level. Besides, it is very affordable. The article highlights the possibility, technical nuances, and the effective implementation of the acoustic emission testing for technical evaluation of process pipelines based on the data obtained during the comprehensive works at Gazprom transgaz Tchaikovsky LLC facilities. It is shown that when combined with smart pigging, the acoustic emission testing allows detecting critical and supercritical defects of any nature.

The main volume of Russian gas is produced in West Siberia from unique globally well-known fields – Urengoy, Yamburg and Medvezhye, which are now at the declining production stage. The continuous decrease in formation pressure has a significant impact both on the gas production potential and well overhaul technology. Under conditions of supercritical pressure drawdown, development of reservoir destruction processes, inflow of formation waters and produced fluid corrosivity growth wells are aging much faster than at initial field development stages. This aspect point to the need to improve the current well operation and overhaul technologies and develop new ones providing higher technical and economic parameters for each well and the developed field on the whole. The present paper considers the relevant scientific and practical task of efficient gas well killing under abnormally low formation pressures with preliminary blocking of the well bore zone by special technical solutions reducing the killing fluid filtration and preserving well production rate nearly at the pre-overhaul level. The paper puts forward a new approach to the quantitative description of the blocking process by means of the mathematical modeling of the high viscosity pill injection into the well bore zone with vertical permeability anisotropy (stratified heterogeneity). The solutions developed based on this model can be used to design the upcoming operation, assess expected process injection mode parameters (pressure/consumption, time), required volume of chemical agents and improve the composition of the blocking solution with account of specific porosity, permeability, pressure and temperature of the formation system.

The article presents the comparative analysis of two basic techniques for the dewatering of large diameter pipelines: vacuum treatment and dry air purge. It is shown that the vacuum treatment is more efficient given the lower power consumption and expenses, and has a number of technological advantages. First and foremost, it makes it possible to remove the moisture from the places of its local accumulation. Secondly, the vacuum treatment has a clear quantitative criterion for zero condensed residual water in a pipeline, which is reaching the pressure of 100 Pa (1 mbar). However, under certain conditions of the cold season, purging a pipeline with warm air might be simpler and more cost-effective than vacuum treatment. The study described some pipeline dewatering equipment: first- and second-generation two-stage vacuum units, as well as the blower with gas-engine driven fan. The paper outlines the ways of further improvement of the structure, reliability, and capacity of the equipment within the entire pressure range. Calculation results are presented for vacuum treatment time needed to dewater a pipeline based on its volume and the amount of water. It is shown that the treatment time depends on the amount of moisture in the first place, whereas the pipeline volume has significantly less effect. The study analyses the practical experience of using vacuum units in various climatic conditions. The original technique of vacuum purge is proposed as the final step of removing the residual moisture from the pipeline before filling it with nitrogen.

The article covers the subject of using nitrogen to create an inert medium inside the main gas pipelines to prevent the formation of explosive gas mixtures and corrosion of pipe material. The functions are provided for explosive concentration limits of nitrogen–oxygen–methane ternary mixtures. The process of mutual gas displacement in different flow patterns is considered in detail, and the formula is provided to calculate the optimal flow rate of displacing gas, which ensures minimum mixing of the nitrogen with the air oxygen. The paper considers process-related and regulatory aspects of using inert mixtures based on nitrogen to prevent the formation of explosive gas-air mixtures in main gas pipelines. Some gaps are identified in the regulatory basis of the activities related to gas pipeline decommissioning and maintaining them under preservation. The paper makes conclusions on the need for prospective development of regulatory and methodological basis on the subject and identifies the aspects that need more detail. Elaboration of technical requirements for main gas pipeline preservation using nitrogen appears to be a particularly immediate task. The document should identify the limits of allowable composition of the inert mixture, the nitrogen sources, the technology of gas pipeline filling with inert mixture, the requirements for monitoring the gas pipeline under preservation, and the algorithm of correcting actions in case of discrepancies from set parameters.

Russian energy strategy involves the most efficient use of natural energy resources and the energy sector potential. PJSC Gazprom develops and implements annual organizational and technical activities aimed at improving the energy efficiency of gas transport. The authority to control energy saving is Gazprom gaznadzor LLC. A detailed study of production processes during the control activities makes it possible to identify the potential for their energy efficiency improvement. Within the inspections, experts of Gazprom gaznadzor LLC develop and propose some technical solutions that have not been considered by the operating organizations when creating their energy efficiency programs. The article provides some of those solutions: altering the fuel gas sampling point for gas pumping units in the compressor yard (economic benefit would be 100,000–200,000 m3/year for one yard), gas purification in the compressor yard (1 % of fuel gas saved), and optimization of the number of dust collector filters in operation and their cleaning method (1,031,600 m3/year saved).

When designing gas transport systems, little attention is paid to terrain conditions. However, they can have a considerable effect on thermodynamic conditions of transported gas. The study analyses the existing calculation models for pressure and temperature distribution of gas transported via trunk pipeline, using density and viscosity parameters. It is shown how elevation difference impacts the gas flow velocity and its specific thermal capacity. The article presents calculated pressure-and-temperature conditions of steady two-phase flow (gas–gas condensate) and describes the terrain-caused velocity fluctuations of gas condensate flow.

Gas condensate from Achimov deposits of the Urengoy field is a strategically important raw material for the petrochemical industry. The condensate contains high amounts of paraffin hydrocarbons, which sets some issues related to its transportation. In Novy Urengoy, a new stabilization unit is being put into operation. It is designed to separate the condensate flow into light and heavy stable fractions to remove the paraffin hydrocarbons from the Urengoy–Surgut pipeline, with heavy condensate fed to Urengoy–Purpe pipeline. Rectification gives the heavy condensate unfavorable rheological properties, making it difficult to transport under Far North conditions. To improve these properties, it is proposed to mix the heavy condensate with Urengoy oil. As a part of the study, the rheological properties of the heavy condensate were examined as follows. Three fractions with different boiling points (220, 234 и 280 °С) were isolated from Achimov condensate and mixed with Urengoy oil in various ratios. Fluid flow parameters were measured on a rotary viscometer with a temperature-controlled cell. Based on the measurements, logarithmic viscosity – inverse temperature curves were plotted. A significant decrease in activation energies was recorded when condensate and oil were mixed. Also, the phase transition temperature decreased by 1–2 °С. The crystallization points of paraffin hydrocarbons were determined in heavy condensate and oil mixtures under the steady and nonsteady flow. The minimum shear rates and volumetric flow rates required to destroy the superstructures at different temperatures were calculated. The minimum allowable temperatures were also determined for transportation of the mixtures with no solidification risk. Oil and condensate were also checked for compatibility in terms of asphaltenes precipitation.

Autonomous low-power sources are used for power supply to such facilities as block valve stations, cathodic protection stations, radio-relay stations when there is no external grid. These sources include renewable energy sources, heat generators, micro-turbine plants, and more. The power range of low-power sources is from one to tens kW. The specific character of their operation is due to buffer rechargeable battery that ensures uninterrupted power supply to consumers in case of sharp load shedding or rise until the source recovers to the set mode. The main shortcoming of buffer batteries is a quite small service life – about 2–4 years, regardless of service life according to their specification (up to 15 years), which is because of the limited number of discharge/charge cycles (maximum of 1000). The article summarizes each stage of implementing the supercapacitor storages in buffer batteries: modeling of hybrid battery, laboratory research, prototype development, pilot operation, and implementation at the existing gas transport infrastructure facilities. Using supercapacitor storages in a hybrid buffer battery system of autonomous energy source is also feasible due to their technical characteristics that remove constraints on charge/discharge cycles during the life cycle. Implementation of the project at existing facilities has shown good results: operation reliability of autonomous sources improved, the service life of rechargeable batteries increased by 3–4 times, and a considerable amount of material resources was saved.