Bulgartransgaz EAD is the owner and operator of an Underground Gas Storage Facility Chiren (Chiren UGS). The company provides services in the energy sector for underground storage of natural gas in a natural geological formation according to License No.Л-214-10/29.11.2006, issued by the EWRC.
The storage facility was created in 1974, based on the depleted gas condensate field of the same name, attached to the Chiren thrust local structure, located about 20 km northeast of Vratsa. The site is located in the land of the village of Chiren in close proximity to the main road connecting the villages of Chiren and Devene.
Chiren UGS serves for the seasonal fluctuation of natural gas consumption in the country and is one of the tools ensuring the security of gas supply.
The purpose of the compressor station at Chiren UGS is to inject natural gas into the natural underground "reservoir". For this purpose, the station at the existing site is equipped with 8 gas piston compressor units. Following the implementation of a project to expand the site, 4 new gas turbines have been installed (GTCUs). A unified system has been built to ensure the technological processes.
The operations at Chiren UGS can generally be split into two periods:
- Production period
It covers the time from November to mid-April of the next year. Natural gas is then produced from the gas storage facility using the exploitation wells. The produced gas is separated from mechanical impurities and the liquid phase in the installations on the site, then dried in a dehydration installation and supplied to consumers.
- Injection period
It covers the period from April to October each year, with natural gas being injected through gas compressor units (GCUs or GTCUs) into the exploitation wells.
With an opinion under article 103 of the EPA of the Minister of the Environment and Water, the classification of the underground gas storage Chiren as a upper-tier establishment has been confirmed.
The following documents have been prepared for the safe operation of the storage facility:
- Safety Report for a upper-tier establishment, approved by Decision under article 99(2) in connection with (4) and (5) of the Environmental Protection Act;
- Major Accident Prevention Policy Report, developed as part of the Safety Report;
- Internal Emergency Plan Part II was developed on the grounds of article 107(1)(3) of the Environmental Protection Act (promulgated in the State Gazette, issue 91 of 25.09.2002) and article 14 of the "Ordinance on the Prevention of Major Accidents with Dangerous Substances and the Limitation of Their Consequences" (promulgated SG, No. 5 of 19 January 2016).
A thorough survey of the production processes and technologies, machines and equipment was carried out in the prepared documents, and the conclusions show that in the event of technogenic events, accidents, explosions, fires, spillage of hazardous substances on the territory of Chiren UGS, danger to life and the health of people from neighbouring settlements is practically non-existent. An accident with a subsequent “domino effect” is not expected.
The corporate Emergency Plan provides for the relevant preventive and remedial measures to be taken in the event of a major production accident and the methods for contacting and notifying the responsible institutions.
The operator Bulgartransgaz EAD has taken all necessary measures to prevent the risk of major accidents and limit their consequences at Chiren UGS sites and the exploitation wells.
Additional information on stored and used hazardous chemical substances, information about the affected public, including the ways of behaviour and actions that the population should undertake in the event of a major accident, summarized information on the dangers of major accidents - scenarios and measures, can be found at the links below:
