Proven reserves at the assets were now estimated at 9.1m barrels of oil equivalent, down from the previous estimate of 17.4m boe.
Output from the Vostochny Makarovskoye and Dobrinskoye fields in the year through December amounted to 4,062 boe per day and Volga Gas said it currently expected that rate to be maintained through 2020. It added that the reserves downgrade would lead to a 'material' non-cash impairment charge.
Chief Executive Andrey Zozulya said: "Management is focused on optimising the recovery of gas and condensate from the [Vostochny Makarovskoye] field and is also actively seeking opportunities to build sources of additional alternative production. Among these additional sources is the unexploited exploration potential for new oil reserves in the group's Karpenskiy licence area".
"To that end, the company plans to intensify its slim hole drilling activities. This technique enables oil and gas production wells to be drilled at a fraction of the cost of a conventional well. The company has seen generally promising results from the first 9 slim hole wells drilled during 2019. More details on this will be provided with the full year 2019 results", Zozulya added.