№ 7 (July - August 2012)
Severneftegazprom Chooses Multilateral Subhorizontal Wells for Yuzhno-Russkoye Field
Severneftegazprom, the operator of the Yuzhno-Russkoye field, plans to increase production in 2012 by 1.4% to 26bn cubic meters of gas a year. The project capacity of the field is currently 25bn cubic meters.
By Lada Ponomareva
The Yuzho-Ruskoye field was chosen as a resource base for the Nord Stream export pipeline through which Russian gas crosses the Baltic Sea to Germany and then to the rest of Europe. The field's reserves total over 1 trillion cubic meters of gas.
During a press tour of the field in June, Severneftegazprom Director Stanislav Tsigankov shared the company's gas productions plans with journalists and representatives of Nord Stream: "Our plans called for producing 25bn cu. m of gas (a level of 25bn cu. m was achieved in 2010 - editor), in 2011 we produced a bit more — 25.63bn cu. m. As far as this year is concerned, we plan to produce even more — 25.95bn cu. m, or maybe even a little more."
One of Severneftegazprom's priority objectives was to attract the maximum number of Russian contractors to the job and to use domestic experience and technologies. The technical project for Yuzhno-Russkoye was executed by TyumenNIIgiprogaz, and Gazprom bureniye was the drilling sub-contractor. Korvet (Kurgan) and Yuzhno-Russkoye prepared a unique dual Christmas-tree, which was used to pump from two Turonian deposits. GROM (Tyumen) aided in designing a spider elevator to pump two bottom-holes into the production string.
Still, foreign companies also participated in the Yuzhno-Russkoye project. Halliburton offered its parallel well completion technology meant for production at sites with separate 73mm production pipeline columns. This system makes it possible to carry out both production and studies separately on each string of a multilateral well and also makes it possible to access the production string in the motherbore and branch hole of the well during further exploitation. This technology was first used when drilling Russia's first test dual lateral producing well with a gradual angle — well 174 used for production at a Turonian field.
A number of German companies also worked on the Severneftegazprom project: Siemens, Prominent GmbH, Hermetic Pumpen GmbH (pump equipment), Unigrid GmbH, Wilo SE, Weishaupt (blow pipes and gas equipment), Sulzer (nozzles for gas dehydration) and other European service companies.
Turonian pilot project
Severneftegazprom is currently developing Senomanian and Turonian deposits at Yuzhno-Russkoye. The main difference between the two types of deposit is the difficulty of production.
"As our experience in Turonian gas production has shown in the past, developing such deposits with the vertical wells traditionally used on Senomanian deposits is ineffective due to the low flow rates and this means we had to search for innovative technological solutions", Tsigankov said, "We chose to drill multilateral subhorizontal wells with dual completions. Without exaggerating, I can say that this experience is unique both in terms of the well construction and the use of special dual Christmas trees and a spider-elevator. No-one here has done that before".
Thanks to cutting-edge tech, the above-mentioned test well number 174 can produce gas from both Senomanian and Turonian deposits at the same time. The depth of the deposits are different at different fields and depend on geological and other parameters. At the Yuzhno-Russkoye field, the Senomanian deposits are from 900 to 1,750 meters deep with gas content from 80-90%. The Turonian deposit lies higher — at a depth of 750 to 900 meters with gas content of 50-80%. However, in contrast to the Senomanian gas, the Turonian gas is what we call a tight resource, since its deposits are sandy with a high level of dense rock".
Tsigankov said that the stable level of production at the Yuzhno-Russkoye field will continue for about another 10 years by exploiting the Turonian deposit, though he added that after 2020, production is expected to decline. Still, according to some estimates, the level of maximum production at 25bn cu. m could continue as long as to 2025-2030 — everything will depend on current annual volumes and the overall geological situation at the field.
A stable resource
Next year as part of its plans to develop Turonian deposits, Severneftegazprom will build lateral test well number 184. There are a total of 143 wells at the Yuzhno-Russkoye field today.
The total volume of deposits in West Siberia are about 3 trillion cu. m and fields int he area are the main resource base for Russian gas exports to Europe (about 80%). Since Senomanian deposits are gradually depleting, further studies and work on Turonian deposits is a high-priority for Russia.
Copyright 2012, OGE. All rights reserved.