A double-bored multilateral well for developing Achimovsky strata — involving a construction unique to Russia — has been commissioned by Gazpromneft-Noyabrskneftegaz at its Vyngayakhinskoye field.* In line with international classifications, the well is deemed to have a “TAML-3” level of complexity.** The well’s construction means oil inflows can be double those achieved in single-barrel wells. Specialists based around the Bolshaya Achimovka project office, including from Gazpromneft-GEO and the Gazprom Neft Science and Technology Centre, were all involved in developing and deploying this technology.
The technology used in fracking the hyper-dense rock of the Achimovsky strata means operations can take place simultaneously in both horizontal boreholes — the lengths of which, at this well, run to more than one kilometre. On commissioning the well (following an eight-stage fracking operation in both boreholes) production reached more than 400 cubic metres of oil-bearing fluid per day. The construction of this well involved drilling a single vertical section, with one single pumping unit then used to allow both horizontal sections to go into operation — significantly reducing capital outlay and production costs.
“Finding ways to develop hard-to-recover reserves, including Achimovsky strata, is one of the key priorities in our technological development. Accordingly, we are developing unique projects, the implementation of which represents a landmark for the domestic oil and gas industry, as a whole. In implementing new technical solutions we are moving towards a whole new level of efficiency in developing hard-to-recover reserves.”Alexey Vashkevich Director for Technological Development, Gazprom Neft
“Developing Achimovsky strata is a national-level project, of major importance to the country’s economy and with the potential to breathe new life into mature fields in Western Siberia. Gazprom Neft will continue fine-tuning and introducing technologies that can improve the viability of developing hard-to-recover oil reserves.”Yuri Masalkin Director for Geological Prospecting and Resource Base Development, Gazprom Neft
* 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.