Core and drill bits with integrated optical analyzer

Abstract

A disclosed method for obtaining a core sample includes directing light at a core sample being collected, receiving reflected light from the core sample, and analyzing the received reflected light to determine one or more characteristics of the core sample and/or form an image of the core sample. Characteristics include rock type, hydrocarbon type, water concentration, porosity, and permeability. The light may be infrared (IR), visible, and/or ultraviolet (UV). The received reflected light may be passed through one or more multivariate optical elements (MOEs). Measurements made at two different positions on the core sample may be used to determine a coring rate. A described coring bit includes a barrel to receive a core sample, a light source illuminating the core sample as it enters the barrel, a detector system that receives reflected light from the core sample, and an optical transmission system communicating light to and from the core sample.

What is claimed is: 
     
         1 . A drill bit comprising:
 fixed cutting teeth to form a borehole through a formation as the bit rotates;   at least one impact arrestor that rides in a groove formed by the cutting teeth; and   an optical analyzer that illuminates the formation through a window in the impact arrestor and analyzes light reflected from the formation.   
     
     
         2 . The bit of  claim 1 , further comprising at least one optical fiber o communicate light between the window and the optical analyzer. 
     
     
         3 . The bit of  claim 1 , wherein the optical analyzer includes a light source, a light sensor, and an optical path from the light source to the light sensor via the window. 
     
     
         4 . The bit of  claim 3 , wherein the optical analyzer includes at least one multivariate optical element (MOE) that intersects the optical path. 
     
     
         5 . The bit of  claim 3 , wherein the optical analyzer includes a filter wheel that successively places different filters in the optical path. 
     
     
         6 . The bit of  claim 5 , wherein at least one of said filters is an MOE. 
     
     
         7 . The bit of  claim 1 , further comprising position and orientation sensors, wherein the analyzer uses information from the position and orientation sensors to associate reflected light measurements with positions in an image log. 
     
     
         8 . The bit of  claim 1 , further comprising a throat that receives a core sample. 
     
     
         9 . A coring bit that comprises:
 cutting teeth to cut a core sample from a formation as the bit rotates;   a throat that receives the core sample as it is cut from the formation; and   an optical analyzer that illuminates the core sample through a window in the throat and analyzes light reflected from the core sample.   
     
     
         10 . The bit of  claim 9 , further comprising at least one optical fiber to communicate light between the window and the optical analyzer. 
     
     
         11 . The bit of  claim 9 , wherein the optical analyzer includes a light source, a light sensor, d an optical path from the light source to the light sensor via the window. 
     
     
         12 . The bit of  claim 11  wherein the optical analyzer includes at least one multivariate optical element (MOE) that intersects the optical path. 
     
     
         13 . The bit of  claim 11 , wherein the optical analyzer includes a filter wheel that successively places different filters in the optical path. 
     
     
         14 . The bit of  claim 13 , wherein at least one of said filters is an MOE. 
     
     
         15 . The bit of  claim 9 , further comprising position and orientation sensors, wherein the analyzer uses information from the position and orientation sensors to associate reflected light measurements with positions in an image log of the core sample's surface. 
     
     
         16 . The bit of  claim 15 , further comprising a second window through which the analyzer measures reflected light for a second image log. 
     
     
         17 . The bit of  claim 16 , wherein the analyzer compares the image logs to determine a coring rate. 
     
     
         18 . The bit of  claim 17 , wherein the analyzer compares the coring rate to a rate determined from the position sensors. 
     
     
         19 . A method for obtaining a core sample, comprising:
 directing light at the core sample as the core sample is being collected downhole;   receiving at least a portion of the light reflected from the core sample; and   analyzing the received reflected light to determine at least one characteristic of the core sample.   
     
     
         20 . The method of  claim 19 , wherein said analyzing operation includes filtering the reflected light with a multivariate optical element. 
     
     
         21 . The method of  claim 19 , wherein the at least one characteristic of the core sample includes at least one of the set of characteristics consisting of: rock type, hydrocarbon type, water concentration, porosity, and permeability. 
     
     
         22 . The method of  claim 19 , further comprising: associating reflected light measurements with positions on a surface of the core sample to obtain an image. 
     
     
         23 . A drill bit comprising:
 teeth to form a borehole through a formation as the bit rotates;   at least one nozzle that passes fluid from an interior flow passage to a region around the teeth;   at least one junk slot that enables the fluid to carry debris away from the teeth; and   an optical analyzer that illuminates the fluid through a window in the nozzle or the junk slot and analyzes light reflected from the fluid.   
     
     
         24 . The bit of  claim 23 , wherein at least some portion of the optical analyzer is positioned in a location formerly designated as a nozzle. 
     
     
         25 . The bit of  claim 23 , wherein the optical analyzer compares light from fluid before it exits the bit and after it interacts with the formation. 
     
     
         26 . The bit of  claim 23 , wherein the optical analyzer includes at least one multivariate optical element (MOE).