UGS Chiren Expansion

Year registered: 2018
3SI countries proposing the project:


Participating 3SI countries:


Partner countries:

* not part of the 3Seas Initiative
Main objectives:

The project for UGS Chiren expansion aims, on one hand, to create conditions that guarantee the security of supply to the Bulgarian users and to the users of the countries of the region.

On the other hand, the UGS Chiren aims to develop as a commercial gas storage on an interconnected regional and pan-European market, as UGS Chiren is an integral part of the regional gas system consisting of interconnections, LNG terminals and storage facilities.

The implementation of the project for Expansion of the capacity of UGS "Chiren" shall lead to:

  • Ensuring security of supply
  • Increasing market integration;
  • Stimulation of market competition;
  • Promoting gas trade in the region.
Short description:

UGS Chiren is the only gas storage on the territory of Bulgaria. It is a key instrument for the functioning of the gas market in Bulgaria, covering seasonal fluctuations in natural gas consumption in the country by securing the necessary flexibility caused by the differences between the supplies and consumption, and ensure emergency reserve. UGS Chiren is a crucial instrument guaranteeing the security of gas supplies.

The project for UGS Chiren expansion envisages a capacity increase in stages of the only gas storage on the territory of Bulgaria in order to allow larger gas volumes stored, increased gas reservoir pressure and higher daily average withdrawal and injection rates. The project provides for increase of the working gas volume up to 1 bcm and increase of the injection and withdrawal rates up to 8-10 mcm/day.

Achieving these goals will be possible through the construction of 10 new high-performance production wells and 3 new observation wells, as well as the construction of the necessary above-ground facilities and infrastructure.

The forthcoming work on the expansion of UGS Chiren is conditionally divided into three directions:

  1. Design and construction of underground facilities;

  2. Design and construction of above ground facilities;

  3. Design and construction of a new high-pressure pipeline connecting the UGS with the existing gas transmission infrastructure.

The conduction of surveys has been finalized in the beginning of 2021. Currently the project is at the stage of FEED and Permitting.

Calendar of implementation:
To be determined

    The 3D seismic surveys, part of the preparatory phase of the project, were co-funded under the Connecting Europe Facility (CEF). The 3D seismic surveys were finalized in early 2021.

    Early in 2021, Bulgartransgaz EAD undertook preliminary activities in order to prepare the project to apply for CEF funding to finance the design and construction stages of the expansion. The procedure is in accordance with Regulation (EU) No 347/2013 and is currently at a stage of submission of investment request to the Regulators.

    Financing sources: