Abstract: An apparatus and method for detecting, locating, tracking, or classifying an acoustic energy source located on a far side of a structure is disclosed. In accordance with the present invention, a receiving device samples a plurality of points on a near side of the structure to detect vibrations that result from sound waves propagated by the acoustic energy source. The location of the acoustic energy source is determined based on the relative time differences of the vibrations and the known positions of the vibrations on the structure. The acoustic energy source may be classified based on identifying characteristics of the vibrations. In addition, a device may be provided to transmit a sound wave through the structure. The receiving devices samples a plurality of points on the near side of the structure to detect vibrations resulting from reflections of the sound wave from the object.

Abstract: A method for reducing the time, cost and apparatus required for monitoring the geometry of the oil/water, oil/gas, or gas/water interface in an underground reservoir. By strategically placing sources and sensors, and by fixing the sensors to the solid earth surface beneath the water, and by knowing the velocity fields in the overburden, the changing edges and geometry of the oil may be determined with significantly reduced data gathering. The strategic positions of the sources and receivers is determined by referencing to the known geometry from past surveys. In addition the velocity of the overburden is known by these prior surveys. In addition, higher resolution of reflectivity areas is achieved by use of sound sources capable of generating higher frequencies compensated for the earth's attenuation and by utilizing long integration times to improve signal to noise ratio. These sound sources can be smaller than prior art sources since they provide directed beams of narrower widths.