Seismic: the motion picture

Geophysicists map underground rock structures by sending seismic waves – essentially sound – through the ground. Sensors record the seismic waves and computers process the recordings to create images of the rock layers. But these seismic images may not be sharp enough to pick up important details. As a result, multi-million dollar exploration wells sometimes end up as dry holes.

The accuracy of seismic imaging could soon improve thanks to a motion sensor, similar to those found in electronic devices like the handheld controllers in a Wii game console. The sensor, developed by computer giant HP and Shell, is 1,000 times more sensitive than those in the Wii.

Dirk Smit, Shell Chief Scientist for Geophysics, was at a nanotechnology conference in late 2008 when he learned of the HP sensor technology. “I realised at once that it could be adapted to record the tiny ground vibrations of exploration seismic waves,” he says.

In conventional seismic surveys hundreds of kilometres of cable are needed to carry the information back to a recording unit. But the new sensors are small enough to fit into a radio transmitter, and they need little power. So they can send information wirelessly – in a similar way to the Wii remote. Eliminating the cables reduces the cost of seismic surveys.

The sensors could potentially be mass-produced, further bringing down costs. This would make it possible to deploy them in far larger numbers than conventional seismic sensors. “Sensors to seismic processing are like pixels to digital cameras,” says Dirk. “The more there are, the higher the image’s resolution.”

If tests under way are successful, thousands of the wireless seismic sensors could be planted like seeds over an exploration area of up to 1,000 square kilometres. They would pick up millions of billions of readings– far more than conventional seismic sensors. And this would give Shell a clearer picture of its drilling targets.