Conclusions

We have discussed, in rather general terms, the requirements on acquisition imposed by using novel sources such as a drill bit or ambient seismic energy. The most important requirement is that the array have the ability to locate incident events in 3-D, since these sources are relatively weak and nearby surface noise sources may overwhelm them unless we are able to distinguish the different arrivals and enhance those we are interested in while attenuating others. To do this we need (at least) a 2-D array of single-component geophones. Sampling and aperture considerations for the array are similar to those for conventional work. Finally, some knowledge of the subsurface geology, a tentative velocity model, or the availability of conventional data can be of great help in processing and provide a reference against which our results can be compared.

These conclusions are relevant to experiments using any source that has the properties described here - relatively low amplitude, an unknown source wavelet, and optionally an unknown source position. Such sources include drill bits, ambient energy, and other sources such as geothermal energy, steam flooding, or pumps.