Bulgaria's domestic production of natural gas last year reached 443 million cubic metres (cu m), compared to only 74 million cu m in 2010, data from the country's economy ministry showed.
Natural gas extraction was carried out by a wholly-owned subsidiary of UK-based Melrose Resources and local company Oil&Gas Exploration and Production. The increase was mainly due to Melrose Resources' two new natural gas deposits discovered near Kaliakra and Kavarna, the ministry said in a bulletin on Bulgaria's energy sector state published on its website.
Last year's natural gas imports rose by 6.0% to 2.81 billion cu m. The entire quantity was delivered by Russia, which remained the Balkan country's single supplier.
Natural gas consumption in 2011 increased by 12% year-on-year to 2.99 billion cu m.
Bulgaria operates the underground gas storage of Chiren which has an annual capacity of 450 million cu m. Last year in Chiren a total 349 million cu m of natural gas were compressed, while 368 million cu m were pumped out.