Oil and gas production was 46 per cent higher last year at AIM-listed Volga Gas thanks to a November upgrade to its processing plant. The Russia-focused company produced a total of approximately 2,922 barrels of oil equivalent per day (boepd) of gas, oil and condensate. The production increase accelerated by a third in December once regulatory approval had been given for upgrade works on its Dobrinskoye Gas Processing Plant, capping what Chief Executive Mikhail Ivanov called "a pivotal year".Second-half production averaged 3,275 boepd, which rose to 4,500 in December after the effects of the upgrade took effect. The company plans make further changes during the first half of 2014 before final approval of the upgrade is expected, allowing Volga to use the plant at full capacity of 1.05m cubic metres per day. Ivanov said: "With the completion of the final stages of the upgrade and the development drilling programme, we look forward to delivering strong growth in revenues and cash flow for Volga Gas in 2014 and beyond."Volga repaid the outstanding balance of a $4.8m loan in December and said it would begin drilling at its VM oil field property in February.Shares in Volga Gas were up 8.1% to 110p at 14:25 on Tuesday.OH