St1 to launch the final phase of drilling the world’s deepest geothermal heat wells in Otaniemi

The final drilling phase of energy company St1’s geothermal heat pilot project is about to begin in Otaniemi, Espoo. The first 6.4 kilometre-deep geothermal heat well was completed last year, and the second well to a depth of 3.3 kilometres awaiting the results of water stimulation modelling. The drilling plan for the remaining part of the second well has been determined according to modelling and the actual drilling will start in September. Once complete in 2020, the plant will be the world’s deepest geothermal heat production plant, which will produce heat completely without emissions.

Drilling equipment was erected at the site in August, and other preparatory work will continue for a few weeks. Seismological measuring instruments will be mounted at the site for collecting data on the future drilling and the plant’s production capacity. The drilling work will last until February 2020.

The most important criteria in the drilling plan are production power, the plant’s expected service life as well as lifecycle costs. Special attention in the plan has also been paid to the possibility of counter stimulation. If it proves necessary, water stimulation will be performed for about two weeks through the well currently being drilled when its final target depth is reached at the beginning of next year. Counter stimulation will make use of the lessons learnt from the successful stimulation completed last summer and any noise defects possibly caused by micro vibrations are minimised.

”Our challenging pilot project on hard Finnish granite bedrock is globally unique. When complete, our plant in Otaniemi will be the deepest geothermal heat production plant in the world. Our aim is to first multiply the concept in the Nordic countries, which will provide a new large-scale emission-free alternative in sustainable heat production. Our project has brought Finnish geoenergy expertise to the global level – in terms of both drilling, stimulation and water flow analysis”, says Matti Pentti, Sti1, Director, Heat from the Ground.

When complete, the Otaniemi geothermal heat plant could cover up to 10% of Espoo’s need for district heat through emission-free energy.

For more information, please contact:

St1, Director, Heat from the Ground, Matti Pentti
tel. +358 50 048 8948,

St1, Production Manager Tero Saarno
tel. +358 50 373 1923,

Video about St1 geothermal heat plant:

St1 Nordic Oy is a Nordic energy group whose vision is to be the leading producer and seller of CO2-aware energy. The Group researches and develops economically viable, environmentally sustainable energy solutions. St1 focuses on fuels marketing activities, oil refining and renewable energy solutions such as waste-based advanced ethanol fuels and industrial wind power. The Group has 1300 St1 and Shell branded retail stations in Finland, Sweden and Norway. Headquartered in Helsinki, St1 employs currently more than 770 people.

St1 Nordic Oy, Interim Report January–June 2019


St1 constructs a biorefinery to produce renewable diesel and jet fuel


Related articles

Read all