Russian oil firm Gazprom Neft has started drilling operations at three exploratory wells at the Chonsky project located in eastern part of Siberia.
Drilling has begun at one each at the project's Ignyalinsky, Vakunaysky and Tympuchikansky fields, located at the border of the Irkutsk Oblast and the Sakha Republic.
Gazpromneft-Angara CEO Victor Sorokin said: "Gazprom Neft has been actively developing the Chonsky project since 2011.
"Continuation of the geological prospecting programme will allow remaining geological uncertainties on this project to be dispelled, and the level of recoverable reserves to be increased.
"The 2014-15 polar season has also witnessed an industry record in terms of seismic operations at the Gazpromneft-Angara licensed blocks, with 4,200 separate pieces of physical data recorded in the course of a single day."
The company is planning to commence drilling a further well at the Tympuchikansky block within a month.
Data gathered from further well testing will be used by Gazprom to determine geological models of the fields, thereby enabling the various blocks to be subsequently prepared for production drilling.
Based on geological prospecting conducted last year, Gazprom Neft has estimated a 50% increase in reserves at the Chonsky project, C1 and C2 reserves, across all three blocks now exceeding 210 million tons of oil and 270 billion cubic meters of gas.
Geological prospecting is being continued at the Chonsky fields with an aim to transfer further reserves from category C2 (probable reserves) to C1 (commercial reserves).
Gazprom plans to prepare the most thoroughly researched blocks in 2015 to carry out production testing next year.