At the Porvoo Works of Neste Oy - Finland's national oil company - underground oil storage caverns of total capacity, of 5.2 million m3 are in operation. In April 1986 the implementation of two additional caverns totalling 150.000 m3 in volume was initiated. The 37 individual caverns are divided into 24 separate plants. The caverns were constructed in 11 phases starting in 1965. Cavern profile areas range from 340 m2 to 580 m2, and have different shapes. The strength of the Precambrian migmatite rock (a mixture of gneiss and granite) has meant that construction methods based on drilling and blasting have been most economical. Vertical shafts 2400 mm in diameter have successfully been drilled with the raise-bore method. Design and construction methods as well as costs for these large unlined openings are presented.
La campagnie petrolière finlandaise nationale NESTE OY dispose actuellement à sa raffinerie de Porvoo de 5.2 millions de m3 de stockage souterrain de petrole. En Avril 1986 deux cavernes supplementaires dúne capacite totale de 150.000 metres cubes etaient mis en construction. Les 37 cavernes etant divisees en 24 depôts detachees sont construites en 11 phases à partir de 1985. Le profil de la caverne varie de 340 metres carres à 580 metres carres etant dune forme differente. Pour raison de la structure compacte des migmatites de Precambrian (une mixture du gneiss et du granite) le methode de forage et 1 explosion se sont montrees les plus economiques. Le forage des puits dexploitation verticals d'un diametre de 2400 mm a ete effectue avec succes conformement à la methode raise-bore. les methodes de planification et construction ainsi que les frais de ces stockages souterrains sont presentes.
Neste Oy - die nationale Ölgesellschaft Finnlands - hat in seinen Porvoo Werken heutzutage Lagerstatten in Felskavernen mit einem Gesamtvolumen von 5.2 millionen m3 fuer Öl im Betrieb. Im April 1986 wurde die Verwirklichung von zwei neue Kavernen mit einem Gesamtvolumen von 150.000 m3 angefangen. Die 37 Einzelkavernen sind in 24 Anlagen geteilt worden. Die Bauarbeiten wurden im Jahre 1965 angefangen und die Kavernen in elf Stufen gabaut. Die Kavernenprofile sind von 340 m2 bis 580 m2 und haben verschiedene Formen. Die Festigkeit des Precambrischen Migmatite Gesteines (eine Mischung von Gneis und Granit) hat bedeutet, dass die Errichtungsmethoden, die sich auf die Bohrung und das Sprengen gruenden, sehr okonomisch gewesen sind. Die vertikalen Böhrlöcher mit dem Durchmesser von 2400 mm sind mit gutem Erfolg mit "raise-bore"-methode gebohrt worden. Die Projektierungs- und Errichtungsmethoden sowie auch die Kosten fuer diese grossen Hohlraume ohne Ausbau werden vorgestellt.
Energy imports to Finland are high, because the climate is cold and many Finnish industries are energy-intensive. Consumption of oil products amounted to about 11 million tons in 1986, equivalent to 35 % of the country s primary energy consumption. Neste Oy, Finland's national oil company is the only company in the country involved in oil, refining. The annual capacity of its two refineries in Porvoo and Naantali is 15 million tons. Climate is one reason why the company must store relatively large amounts of crude oil i.e. 3 to 4 million tons, for winter use; it is stored In large unlined rock caverns excavated into the bedrock at the refineries. The crude oil storage caverns at the Porvoo Works (Fig. 1.) have a combined capacity of about 3.3 million m3, divided between 14 separate plants. In addition the refinery also operates 8 caverns for storage of oil products, with a combined capacity of about 1.9 million m. The total number of individual caverns is 35. In late April 1986 construction of two additional cavern plants, for storage of light gas condensate and propane was initiated. The total capacity of these two pressurized caverns will be 150.000 m3, and the caverns are scheduled to be operational by the end of 1987. All caverns operate according to the well-known Scandinavian method, i.e. the caverns are located well below the ground water level in bedrock that provides the necessary stability and tightness. No artificial linings are used.
Neste Oy's Porvoo Works are located about 50 km east of Helsinki on the Southern coast of the Gulf of Finland in the eastern part of the Baltic Sea. The Precambrian rock crust in the area is a typical part of the Baltic or Fennoscandian Shield which is the broadest shield area on the European continent.
