High-resolution seismic exploration system in boreholes - Seismic Prediction While Drilling (SPWD)

Several borehole seismic methods are in use while drilling. Because the sought-after small-scale structures like thin local layers or faults encountered more and more in deeper regions the focus of exploration has shifted to methods with higher resolution. Combining a seismic source and receiver in a common device in the drill string would increase the seismic resolution. Within the project (S)PWD a first prototype of such a Seismic Prediction While Drilling (SPWD) device has been designed and tested in dry horizontal boreholes. With source signal frequencies up to 5000 Hz a resolution of about one meter is feasible. By focusing the seismic waves the energy can be maximized in desired directions. An increased radiation of seismic wave energy in direction of the borehole axis allows the view in areas to be drilled. If applied while drilling such a tool allows adjusting the drill path to minimize risks and costs of drilling. The next step in the project (S)PWD will be in 2010 the development of a wireline SPWD prototype for vertical boreholes with depths to 2000 m.