Abstract: Apparatus is provided for determining the conformity of an energy pulse generated by a weight drop seismic source to a defined energy pulse characteristic in order that reflections associated with a non-conforming energy pulse can be rejected. The apparatus operates to compare the signature of a weight drop with a signature standard. Incoming seismic data is rejected and not recorded if the difference between the incoming signature pulse shape and the standard signature pulse shape is too great. The pulse shape of the incoming signature is analyzed by comparing a sample of the incoming signature amplitude to upper and lower rejection limits derived from a time correlated amplitude sample of the standard signature. The upper and lower rejection limits against which an incoming signature sample is compared are proportional to the amplitude of the time correlated standard signature sample.

Abstract: We have found it possible to investigate subsurface formations in the expectation of locating promising gas fields by a unique refraction seismic technique. Basically one carries out a two-way seismic refraction profile for a fixed spread of geophones and explosions (or equivalent impulse sources) beyond the critical reflection range for shallow refractors, but still rather close to the spread. Then without moving the spread, reproducible records are also made for a two-way seismic refraction profile with the explosions or equivalent sources spaced as far away as convenient, so the refraction paths to the detector groups in the spread is up-going to the detectors for the maximum thickness of beds intervening between the refractor and the group of geophones.

Abstract: Disclosed is a method of processing geological seismic reflection data to compensate for lateral variations in the attenuation effect which the weathered layer has on the reflected seismic energy waves as they approach an array of detectors at the surface. Absolute amplitudes of the waves are summed for each trace throughout a test window at the depth to be explored. The amplitudes are normalized by taking the ratio of each sum to the sum of the absolute amplitudes obtained throughout a standard window, in the corresponding trace. In a particular embodiment disclosed, the test window scans each trace in increments, and the absolute amplitude sum obtained at each position is normalized to the standard window in that trace. The ratios thus obtained, when plotted, reveal the positions of large-amplitude reflecting strata without weathered-layer distortion.

Abstract: A method of locating near-surface underground chambers, rooms, caves, pits, tubes, faults in surface rocks, and the like, using acoustic techniques is disclosed. For mapping large areas, a survey grid for transmitter transducer placement first is laid out over the area of interest.A transmitting transducer is coupled to the bedrock at one of the grid sites, and acoustic waves are generated in the earth by operation thereof. Portable acoustic receiving means, including a receiving transducer, are used to detect acoustic waves from the transmitter at a plurality of receiving sites surrounding the transmitting station. Transmitted acoustic waves from the transmitting site received by the receiving transducer are converted to electrical signals by the receiving transducer and recorded for subsequent use. Following operation of the receiving means at each receiving site surrounding the transmitter transducer, the received signals are compared to determine any differences in their magnitudes.

Abstract: A method of producing a display of acoustic velocity characteristics of individual strata in a geologic section includes propagating broad-band acoustic energy into the earth, detecting reflected energy from multiple strata at an array of receiving stations, recording the received signals, normalizing the signals representing the energy received from each strata interface for losses due to the strata above that interface to restore the signal levels and to derive a sequence of loss factors, filtering the low frequency signals from the resulting signals, adding to the resulting filtered signals a set of gross velocity profile signals and displaying the results.