The new concert, congress and hotel centre Malmö Live is designed to meet the toughest demands for environmental friendliness. Initially the drilling for geothermal heating was performed with air-powered DTH hammer and large amount of water was being pumped up from the ground and caused problems.
The drilling project was likely to be delayed significantly. By drilling with Wassaras water-powered DTH hammer instead, the water in the formation was not affected at all and the delay was heavily reduced.
Background to the project
The new Malmö Live centre in Malmö is scheduled to be opened during summer 2015. The block will comprise some 90 000 m2. The congress facilities will seat 1 500 people while the concert hall will seat 1 600. The hotel will be 85 meter high, comprising over 400 rooms and a sky bar at the 25th floor.
One goal is to see the centre certified according to LEED (Leadership in Energy and Environmental Design). It consists of a suite of rating systems for high performance green buildings, homes and neighbourhoods. Malmö Live actually aims to meet the highest LEED standards, named Platinum. One of the many environmentally friendly solutions is the geothermal heating system that consists of 75 boreholes, each 280 meter deep.
Initial drilling in a very water-rich formation
Initially, the geothermal holes were drilled with air-powered DTH hammers. This soon got complicated as the Malmö formation turned out to be very water-rich. The air-powered drilling equipment quickly turned into a pumping system as the expanding air was pushing large amounts of water up the borehole when leaving the air-powered DTH hammer. Estimations indicated about 100 m3 of water being pumped up each hour. The water management system onsite could not manage this amount of water and several interruptions in drilling were required. The water also reduced the drilling performance heavily; after 3 weeks of drilling, less than 10% of the boreholes where done. The 10 weeks that was set aside for the entire drilling phase would not be sufficient. Clearly, this was not acceptable.
Drilling with water-powered equipment in water-rich formation
The Wassara DTH hammer, W120, requires some 340 liter per minute during operation. As this equals 20m3 of water per hour, the difference is drastic. This volume is used for powering the hammer, not pumping water from the borehole. The water-powered drilling doesn’t affect the water in the formation at all.
When drilling with high-pressure water, the water flows like it would in a U-formed tube (as the inner flow in the drill string goes downwards and the outer flow goes upwards in the borehole). This gives the possibility to drill in water-rich formations without problem and regardless of borehole depth.
The principles of water-powered drilling
By changing to drilling with Wassara water-powered DTH hammers, the delay of the operation was heavily reduced and the drilling phase was completed in an acceptable time frame.
The MTD drill rig, also equipped with Wassara