Abstract: Disclosed is a seismic data gathering system for use in well drilling operations. A seismic pulse generator may be placed in the drill string near the drill bit and advanced in the well for generation of seismic pulses at any depth. An array of seismometers, rotationally symmetric about the well, may be arranged at the surface to detect both pulses refracted above the seismic pulse generator and pulses reflected at interfaces below the generator. According to the method of the invention, the refracted and reflected seismic pulse data may be reduced and analyzed to determine the drilling direction of the drill bit, the lithology through which the drill is passing, the position and approximate shape of nearby oil or gas reservoirs otherwise missed, and to look ahead of the drill bit to determine geologic conditions in advance of the drilling.