Patent ID: 6140637
Filing Date: 2000-10-31
Classification: E21B,G01V

Abstract:
A method of locating in situ hydrocarbons in underground formations surrounding a borehole comprising:a) placing a tool including a light source, a detector and a window in a borehole,b) moving the tool through the borehole,c) illuminating a wall of the borehole as the tool is moved through the borehole with light from the source via the window which is pressed against the borehole wall with sufficient force to displace any mudcake, the pressure applied at the window when in contact with the borehole wall being substantially greater than the overpressure of fluid in the borehole,d) detecting any fluorescence from the wall with the detector through the window in the tool, ande) analyzing the detected fluorescence to determine the presence of hydrocarbon in the formation.