The numbers say it all
A geothermal installation at Langara community college in Vancouver, Canada, became the setting for a duel between old and new technology. After encountering extreme soil conditions, a sonic drill rig was brought in as the “rescue rig” for the project. The numbers explain why.
In this example, a sonic rig was used to finish a library/classroom addition for the Langara community college in Vancouver, BC – a project that subsequently won an award for sustainable construction. In the Langara case history, three rival conventional rigs had been working the site for nearly two months and, in that time period, they had succeeded in drilling 18 holes in total.
Without question, it was a driller’s nightmare. Under the Langara site, the soil was a diverse mixture of sand, till and gravel and littered with large boulders – daunting terrain no matter what kind of rig worked it. Despite the soil conditions, a single sonic rig was able to drill, case, loop and grout 23 geothermal holes in two weeks flat. It was a stunning result given that it had taken three standard rigs nearly two months to accomplish much less.
Understandably, the skeptics often shake their heads disbelievingly when confronted with the evidence of a sonic rig in action, but, in the geothermal arena, it has no competitors. However, that still leaves the big question of how does it do on harder material like granite bedrock? Clearly, the sonic rig’s biggest performance advantage comes from its unequalled ability to buzz through the kind of mixed soils that would jam or bog down other kinds of rigs – causing delays, equipment breakdowns and safety hazards.
The good news is that on hard bedrock the sonic rig carries on, delivering drilling rates similar to conventional rigs. Equipped with a carbide-tipped drill bit, the sonic rig can bore through tough bedrock at the same speed as other rigs – not necessarily providing a speed advantage but producing an equal result (although, on softer bedrock there is a moderate speed advantage, depending on the ground conditions).
However, when that bedrock layer is topped by mixed soils, the sonic rig now earns its much-loved reputation from both drillers and owners since there is no need to swap out drill rigs to adjust to changing ground conditions. The sonic rig can deliver its blistering speed advantage through mixed soils and then slow to conventional drill rates through bedrock – but still provide the benefit of not needing to delay projects for a rig swap.
Old vs. New Drilling Technology |
|
|---|---|
Conventional Rig |
Sonic Drill Rig |
Three rigs on site |
One rig on site |
Two months on site |
Two weeks on site |
18 holes installed |
23 holes installed |
10 days per hole |
1-2 holes per day |