Symmetrix the solution as IKEA goes geothermal
Published 2010-01-15 23:08:37 | Updated 2010-01-29 14:32:28
Sixty wells, each 200 m deep were drilled into bedrock in just ten days – part of a geothermal energy system for the new IKEA store in the city of Tampere, Finland. Challenging ground conditions were overcome by Symmetrix drilling technology.
When IKEA’s new store opens in Tampere, Finland, the 37 500 m2 building will be heated and cooled using only geothermal energy. The project is the largest of its kind in the country and part of IKEA’s long-term programme to have all IKEA buildings powered by 100 percent renewable energy.
Geothermal energy is solar energy, stored in the bedrock. Using heat pumps, this energy is collected from the ground via holes and used for heating buildings and water. And the popularity of this environmentally-friendly energy source is increasing rapidly; in Finland, 7 500 ground source heat pumps were sold in 2008 – a 42 percent increase on the previous year.
Loose ground
After the groundwork was completed at the site of the new IKEA store, the surface consisted of a three-metre layer of unconsolidated rock. Drilling the 60 energy wells would require a system that could both drill and advance a casing pipe at the same time.
The contract to drill the 60 energy wells was awarded to drilling contractor Suomen Porauspalvelu. With each hole 200 m deep, a total of 12 km of drilling was required. The wells were designed in five rows, each consisting of 12 wells. The wells in the central row were drilled vertically. The two rows either side of this row were drilled with an inclination of five degrees. The wells in the outermost two rows had an inclination of ten degrees away from the centre row. The holes were drilled in this way to ensure sufficient space between each hole at the 200 m depth, regardless of deviation.
A case for Symmetrix
A range of Atlas Copco products were selected for the project which included the compressors, drill rods, Symmetrix P140/5-115 casing advancement system, Secoroc 115 mm bits, Secoroc COP44 and TD40 DTH hammers. Jukka Ahonen, General Manager, Atlas Copco Rotex explains that the Symmetrix system was ideally suited to the ground conditions. “At this site, there was an unconsolidated layer of rock created by blasting and excavation works,” he explains. “Passing this layer quickly and efficiently was the key to achieving high productivity.” The Symmetrix system consists of drill bits and a casing shoe that is welded to a casing tube. Using percussive drilling, the drill bit drills a hole large enough for the casing tube to advance down the hole. With this system, it is possible to install casing tubes through hard and rocky unconsolidated material and into the bedrock. The contact area of the casing tube and bedrock is sealed in order to prevent surface water entering the well.
Rapid drilling
Drilling began with the Symmetrix system in August installing permanent casings with an outer diameter 140 mm. After this, drilling was carried out through the cased hole using Secoroc 115 mm bits until the final depth was reached. The time schedule for the assignment was tight and Suomen Porauspalvelu put its entire fleet of three drilling rigs onto the project. The work, including 12 km of drilling was completed in just ten working days. Tor Enqvist, Joint Owner, Suomen Porauspalvelu, says: “A condition of this contract was that it could be completed within a tight timeframe. We are pleased to have managed with this challenging schedule. Since 2007, when we started our company, we have chosen to invest in modern, high quality tools and machines. By doing so we can meet our customer expectations, both in terms of reliability and productivity.”
(Published with permission from Atlas Copco magazine Mining & Construction)
