* The Achimovsky strata are located in the lower part of Cretaceous (chalk) deposits almost directly above the oil-bearing Bazhen Formation (strata in Western Siberia, lying at a depth of two to four kilometres). The Achimovsky strata occur throughout virtually the entire West Siberian basin, covering an area of 900,000 square kilometres, with the thickest strata found in the Nadymsky and Purovsky Districts of the Yamal-Nenets Autonomous Okrug. The Achimovsky strata are characterised by a complex geological structure, necessitating the use of technologically complex techniques in their development.

Experts estimate oil reserves at Achimovsky strata to be in the order of 60 billion tonnes. Gazprom Neft’s “Bloshaya Achimovka” project office has been set up to find viable technologies for developing this resource base — drilling unique wells being one of the company’s promising technology projects here.

** “TAML-3” refers to one of six levels of complexity in multilateral well finishing: levels being distinguished from one another by the nature of their construction, and the type of finishing used on sidetracks. TAML-3 main boreholes and sidetracks are finished without cement casings.

*** Hydraulic fracturing (fracking) involves the high-pressure injection of a special fluid into a well, causing fissures to form in the rock, through which oil is then able to flow. The larger the area covered by these fissures, the more oil will be produced.