GB1516281A - Hydrocarbon exploration - Google Patents

Abstract

1516281 Prospecting BARRINGER RESEARCH Ltd 26 April 1976 16918/76 Heading E1F [Also in Divisions G1 and H4] The presence of hydrocarbon seeps in the sea is determined by directing into the sea a beam of light radiation of sufficient intensity and of such wavelength that it produces light which emanates from subsurface zones of the sea and which is attributable to reflections and/or bioluminescence in the zones. As described, light from a pulsed laser 13 is reflected from a mirror 14 down from a low flying aircraft (Fig. 1, not shown) to layers of scattering (15) in the sea associated with increased microbiological activity and the presence of gas bubbles, reflected light being received by a telescope 17, a photomultiplier 18 and an oscilloscope 19 operating in synchronism with laser 13. The face of oscilloscope 19 may be photographed continuously to provide a permanent record of the intensity of observed surface reflections. A second trace can be displayed on the or another oscilloscope by splitting the output of telescope 17 using a dichroic mirror 20, Fig. 3 (not shown), one wavelength being that of laser 13 and the other being a longer wavelength representing bioluminescence. The oscilloscope display enables signals received from the sea surface (e.g. polluting oil slicks) to be differentiated from sub-surface scattering and bioluminescence, although other forms of recording (e.g. digital) could be employed. The laser wavelength is preferably in the blue or ultraviolet to achieve maximum sensitivity to scattering in the water and to stimulate bioluminescence in the suspended microorganisms.