Optical fluid analyzer sampling tool using open beam optical construction

Abstract

An apparatus for estimating a property of a fluid of interest downhole includes: a carrier configured to be conveyed through a borehole penetrating an earth formation; an emitter disposed at the carrier and configured to emit electromagnetic energy; and a sample chamber configured to contain a sample of the fluid of interest and having a window transmissive to electromagnetic energy emitted by the emitter, the electromagnetic energy interacting with the sample of the fluid of interest with a characteristic related to the property; wherein a path of the emitted electromagnetic energy from the emitter to the window of the sample chamber traverses a gas or a vacuum.

What is claimed is: 
     
         1 . An apparatus for estimating a property of a fluid of interest downhole, the apparatus comprising:
 a carrier configured to be conveyed through a borehole penetrating an earth formation;   an emitter disposed at the carrier and configured to emit electromagnetic energy; and   a sample chamber configured to contain a sample of the fluid of interest and comprising a window transmissive to electromagnetic energy emitted by the emitter, the electromagnetic energy interacting with the sample of the fluid of interest with a characteristic related to the property;   wherein a path of the emitted electromagnetic energy from the emitter to the window of the sample chamber traverses a gas or a vacuum.   
     
     
         2 . The apparatus according to  claim 1 , wherein the optical path does not traverse an optical fiber. 
     
     
         3 . The apparatus according to  claim 1 , wherein the optical path traverses one or more optical elements configured to focus the emitted electromagnetic energy. 
     
     
         4 . The apparatus according to  claim 1 , further comprising a housing configured to contain the gas or provide the vacuum. 
     
     
         5 . The apparatus according to  claim 4 , wherein the housing is further configured to support one or more optical elements configured to focus the emitted electromagnetic energy. 
     
     
         6 . The apparatus according to  claim 1 , further comprising an analyzer configured to analyze electromagnetic energy that interacted with the fluid of interest to estimate the property, the electromagnetic energy that interacted with the fluid of interest traversing the window and following a path that traverses a gas or a vacuum. 
     
     
         7 . The apparatus according to  claim 6 , wherein the analyzer comprises a grating spectrometer. 
     
     
         8 . The apparatus according to  claim 1 , wherein the window comprises a crystal. 
     
     
         9 . The apparatus according to  claim 8 , wherein the window is a plate window having two parallel planes. 
     
     
         10 . The apparatus according to  claim 9 , wherein an optical axis of the plate window is perpendicular to the planes. 
     
     
         11 . The apparatus according to  claim 10 , wherein the emitted electromagnetic energy enters the window at an angle greater than zero with respect to the optical axis. 
     
     
         12 . The apparatus according to  claim 7 , wherein the crystal comprises a sapphire crystal or a diamond crystal. 
     
     
         13 . The apparatus according to  claim 1 , wherein the carrier comprises a wireline, a slickline, a drill string, or coiled tubing. 
     
     
         14 . An apparatus for estimating a property of a fluid of interest downhole, the apparatus comprising:
 a carrier configured to be conveyed through a borehole penetrating an earth formation;   an emitter disposed at the carrier and configured to emit electromagnetic energy;   a sample chamber configured to contain a sample of the fluid of interest and comprising a window transmissive to electromagnetic energy emitted by the emitter, the electromagnetic energy interacting with the sample of the fluid of interest with a characteristic related to the property; and   an analyzer configured to receive and analyze electromagnetic energy that interacted with the fluid of interest to estimate the property;   wherein a path of the emitted electromagnetic energy from the emitter to the window and another path from the window to the analyzer traverses a gas or a vacuum.   
     
     
         15 . The apparatus according to  claim 14 , wherein the electromagnetic energy emitted by the emitter and the electromagnetic energy received by the analyzer traverses the same window. 
     
     
         16 . The apparatus according to  claim 15 , wherein the analyzer is configured to perform reflective spectroscopy. 
     
     
         17 . The apparatus according to  claim 14 , wherein the window comprises a first window configured to pass the electromagnetic energy emitted by the emitter and a second window configured to pass the electromagnetic energy received by the analyzer. 
     
     
         18 . The apparatus according to  claim 14 , wherein the analyzer is configured for transmissive spectroscopy. 
     
     
         19 . A method for estimating a property of a fluid of interest downhole, the method comprising:
 conveying a carrier though a borehole penetrating an earth formation;   containing a sample of the fluid of interest in a sample chamber comprising a window transmissive to electromagnetic energy; and   emitting electromagnetic energy from an emitter disposed at the carrier to the at least one window along a path that traverses a gas or a vacuum;   wherein the emitted electromagnetic energy traverses the at least one window and interacts with the sample with a characteristic related to the property.   
     
     
         20 . The method according to  claim 17 , further comprising receiving electromagnetic energy that interacted with the sample using an analyzer configured analyze the received electromagnetic energy to correlate the characteristic to the property. 
     
     
         21 . The method according to  claim 17 , wherein the window comprises a crystal plate having two parallel planes with an optical axis perpendicular to the planes and the emitted electromagnetic energy enters the window at an angle greater than zero with respect to the optical axis.