Liquefied petroleum gas: prospects for alternative applications

. This article analyzes the production of natural gas product and its application in the territory of Eastern Siberia and the Far East. In this territory a significant number of hydrocarbon deposits are dispersed, with the current volume of production already formed natural gas reserves for more than 150 years, and further plans to increase the resource base, which is a strategic priority. But promising ways of sales are needed, so the logistical situation in these territories was analyzed. The problems of realization of this resource in the territory due to the difficult logistical situation were revealed. The analysis of the prospective use of liquefied petroleum gas in Russia and the prospects of exporting to other countries. Based on the performed analysis the proposal has been formed on the development of the excessive amount of the gas product in the territory, the proposed solution meets all the requirements and is relevant to the territory. And as to confirm the economic benefits, the effectiveness of the proposed approach to the development of surplus gas production has been assessed, which also confirmed that this solution is relevant for Eastern Siberia and the Far East.


Introduction
Eastern Siberia and the Far East are regions of priority presence of the state-owned companies Rosneft and Gazprom. Proven hydrocarbon reserves in the region are dispersed across a number of large and a large number of smaller fields, located at considerable distances from each other and from oil and gas consumption and processing sites, and are located in regions without any hydrocarbon transportation infrastructure. It is difficult to access hydrocarbon raw materials produced from all fields in the region to the oil and gas export markets.

Main part
"New external consumers, the reversal of exports from west to east is a new direction of Russian gas imports. In 2020, the total volume of natural gas exports to the east amounted to 26 billion cubic meters.
The People's Republic of China (PRC) is the main potential buyer of Russian gas. Due to its geographical location, it receives almost all the available and potential gas resources of the eastern part of the country, which are currently not connected to the Unified Gas Supply System (UGSS). The main routes of Russian natural gas supplies to the PRC are shown in Figure 1. Taking into account these routes and the already concluded contracts, the planned volumes of gas exports to the East by 2030 will be about 60-65 bcm are shown in the diagram in Figure 2. Additional gas volumes through the implementation of the Power of Siberia-2 project will amount to 50 bcm after its launch in 2030. However, it is worth noting that the resource base for planned deliveries in 2030 is the Eastern Siberian fields. The current production is mainly carried out in the fields of Western Siberia, which is the resource base for exports to Europe. Additional supplies through the Siberian Sila-2 may be made at the expense of Western Siberian resources, but they will not be able to fully replace European supplies. Therefore, it seems that with reduced supplies to Europe, production volumes at current West Siberian sites may decrease, and production volumes at "new" fields in East Siberia may increase.
At present, there is virtually no gas industry in the eastern regions of Siberia, not counting several local gas supply systems in the Republic of Sakha (Yakutia) and in the north of Krasnoyarsk Krai. In the near future, a major gas complex will be created here, including the sectors of production, processing, transportation of gas and gas products.
Exports to South-East Asia are limited by the throughput capacity of railroads and are also marginal due to the LPG transportation tariff. This creates a surplus in the Russian perimeter. The surplus leads to a decrease in the value of LPG as a commodity product.
An important specific feature of East Siberian fields is their remoteness and transport isolation: there is no railway network, poorly developed road connections, and no bridge over the Lena River.
It is expensive to build product pipelines. These factors make it difficult to export and sell the LPG and NGL produced during gas treatment. We should also note the lack of port infrastructure for transshipment of LPG by sea to the Asia-Pacific region.
Therefore, one possible solution to the problem of a surplus of produced gas is to propose the use of LPG on-site and in nearby locations.
Having analyzed the gas production, the charts of forecasts of gas supplies to China, the perspective gas production by 3 fields of PJSC "YATEC" and the assessment of the potential content of LPG in the gas of 2022 (Figure 3, 4) show a significant increase in both production and the volume of forecast growth in gas supplies. But given the logistical situation in Eastern Siberia and the Far East and the inability to build both a pipeline and port infrastructure to transport LPG by sea to the regions, a solution aimed at developing reserves in this area is needed. The factors that influence the choice of the decision were studied and taken into account: -Analysis of prospective gas production of PJSC "YATEC" -Analysis of PJSC YATEC's product supplies and their strategic -Programs for expanding the international geography of operations.
-The possibility of LPG existence at ambient temperatures and moderate pressures, both in liquid and gaseous states.
-The use of LPG in many industries. As part of this study it was proposed to use LPG as a fuel for generating electricity by reequipping the current cogeneration plants. "It will be possible on the basis of a new highly economical gas turbine module of the 5th generation GTE-004 with the capacity of 4 MW and efficiency of 41,5% with the possibility of disassembly and reassembly on site. This power unit is intended for use in heat supply systems of housing and public utilities and industrial enterprises. High efficiency of this cycle lies in the reduction of compression work by intermediate air cooling between the compressor stages and fuel saving through the use of a regenerative regenerator (RRC) for compressed air preheating before the combustion chamber of the gas turbine. The power unit compactness is achieved by using high-speed gas generator (18000 rpm), power turbine and turbogenerator (at 12600 rpm). Power Unit GTE-004 is new at the power engineering market, in this connection it is of interest to define its power and economic performance".

Conclusion
The proposed solution of using liquefied gas as fuel for power generation by means of reequipment of the current cogeneration plants or construction of new ones next to the newly discovered fields using the innovative gas-turbine modules, is relevant for this area. The payback period of investments in the construction of a cogeneration plant was determined using the graph of changes in the accumulated NPV from the calculation step number and was 6.4 years. Analysis of the results shows that the project of GTU-CHPP construction on the basis of GTE-004 power units is effective. Prospective gas production at three fields of YATEC