Method and apparatus for fluorescence logging

摘要

A method of locating in situ hydrocarbons in underground formations comprises illuminating the borehole wall with light such as visible, infrared or ultraviolet light or combinations of these, from a source in a tool such as a wireline logging tool or an LWD tool, detecting any fluorescent radiation with a detector in the tool and analyzing the florescent radiation to determine the presence of hydrocarbon in the formation. The tool is moved through the borehole while irradiating the formation and detecting fluorescence. The borehole wall is illuminated and fluorescence detected through a window in the tool which is pressed against the borehole wall with sufficient force to displace any mudcake. The window is made of a wear resistant material such sapphire or diamond and is conveniently secured in a wear resistant housing which might be made of tungsten carbide or the like.