Abstract: A method for detecting hydrocarbon zones in a geological formation, including obtaining a plurality of pulverized drill cutting samples representative of the geological material encountered at measured depth intervals, each drill cutting obtained at periodic intervals during the drilling process; measuring each cutting sample with a color measuring device to obtain a value representing the degree of lightness of the particular cutting sample; and analyzing the measured lightness values by order of borehole depth that the respective cutting sample was obtained to determine the presence of geological zones likely to possess producible hydrocarbons. L* data may be combined with other well logging data to improve the hydrocarbon layer determination accuracy. A method also for locating the drill bit within a desired hydrocarbon layer during directional drilling.

Abstract: A method for detecting hydrocarbon zones in a geological formation, including obtaining a plurality of pulverized drill cutting samples representative of the geological material encountered at measured depth intervals, each drill cutting obtained at periodic intervals during the drilling process; measuring each cutting sample with a color measuring device to obtain a value representing the degree of lightness of the particular cutting sample; and analyzing the measured lightness values by order of borehole depth that the respective cutting sample was obtained to determine the presence of geological zones likely to possess producible hydrocarbons. L* data may be combined with other well logging data to improve the hydrocarbon layer determination accuracy. A method also for locating the drill bit within a desired hydrocarbon layer during directional drilling.

Abstract: A tool for obtaining samples of the formation surrounding the wellbore, and method of obtaining such samples, is disclosed. The tool is implemented within a sub in a bottomhole assembly, preferably within side-pocket mandrels in the outer surface of drill collar pipe. The tool includes a series of sampling bits that may be fired into the surrounding formation by the activation of an explosive charge, and also includes an electronic unit for detecting a signal from the surface and activating the charge in response thereto. The signal may be communicated by way of mud-pulse telemetry, or by any other known telemetry technique. Separate groups of sampling bits, with separate switch and power units, may be provided to provide redundant operation; a decoder is included in this alternative, to allow for selection of one of the groups.