Method and apparatus for estimating a downhole fluid property using a rare earth doped laser

Abstract

A method and apparatus are disclosed for estimating a property of a downhole fluid, the apparatus including but not limited to a carrier that is conveyable in a borehole; a test cell carried by the carrier for capturing the downhole fluid; a rare earth doped electromagnetic energy source in electromagnetic energy communication with the downhole fluid in the test cell; and an electromagnetic energy detector in electromagnetic energy communication with electromagnetic energy emitted by the rare earth doped electromagnetic energy source that has interacted with the fluid for estimating the property of the downhole fluid.

What is claimed is: 
     
         1 . An apparatus for estimating a property of a downhole fluid, the apparatus comprising:
 a carrier that is conveyable in a borehole;   a test cell carried by the carrier for capturing the downhole fluid;   a rare earth doped electromagnetic energy source in electromagnetic energy communication with the downhole fluid in the test cell;   and   an electromagnetic energy detector in electromagnetic energy communication with electromagnetic energy emitted by the rare earth doped electromagnetic energy source that has interacted with the fluid for estimating the property of the downhole fluid.   
     
     
         2 . The apparatus of  claim 1 , wherein the electromagnetic energy detector is a photodetector and wherein the electromagnetic energy source is a rare earth doped laser selected from at least one of a rare earth doped fiber laser, a rare earth doped silicon on insulator laser and a quantum dot laser, the apparatus further comprising:
 an electromagnetic energy pump in optical communication with the rare earth doped electromagnetic energy source.   
     
     
         3 . The apparatus of  claim 2 , wherein the electromagnetic energy pump, rare earth doped laser and photo detector are located downhole, the apparatus further comprising:
 an electro optic modulator integrated into the rare earth doped laser for adjusting a frequency of electromagnetic energy emitted from the rare earth doped laser to a wavelength of interest for detecting the property of the downhole fluid.   
     
     
         4 . The apparatus of  claim 3 , wherein the electro optic modulator device is an integrated device is at least one of an integrated stress tuner and a thermal to and wherein the rare earth doped laser further comprises a plurality of rare earth doped lasers integrated on a silicon wafer with the electro optic modulator, wherein each of the plurality of rare earth doped lasers' frequency of electromagnetic energy output is tunable using the electro optic modulator. 
     
     
         5 . The apparatus of  claim 2 , wherein the rare earth doped laser further comprises a nanocavity in a two-dimensional photonic crystal slab wherein a Q for the rare earth doped laser is higher than about 1000. 
     
     
         6 . The apparatus of  claim 1 , wherein the rare earth electromagnetic energy source is a surrounding medium refractive index (SRI) sensor immersed in the downhole fluid wherein electromagnetic energy from the electromagnetic energy source indicates an SRI of the downhole fluid, wherein the SRI for the downhole fluid is used in estimating the property of the fluid. 
     
     
         7 . The apparatus of  claim 1 , the apparatus further comprising:
 an electromagnetic energy pump located outside of the test cell;   a window formed in a side of the test cell for ingress and egress of electromagnetic energy to and from the test cell, wherein electromagnetic energy detector and the electromagnetic energy pump are located outside of the test cell and the electromagnetic energy source is located inside of the test cell, wherein the electromagnetic energy pump further comprises gratings, each of which reflect electromagnetic energy at a frequency of interest from electromagnetic energy that has interacted with the fluid, to detect a compound of interest in the fluid.   
     
     
         8 . The apparatus of  claim 1 , wherein the electromagnetic energy that has interacted with the fluid is at least one of electromagnetic energy that has passed through the downhole fluid, electromagnetic energy that fluoresces from the downhole fluid and electromagnetic energy that has reflected off of the downhole fluid, wherein the electromagnetic energy source further comprises gratings, each of which reflect electromagnetic energy at a frequency of interest from electromagnetic energy that has interacted with the fluid, to detect a compound of interest in the fluid, the apparatus further comprising:
 a processor configured to analyze the electromagnetic energy that has interacted with the downhole fluid for transmittance, fluorescence, absorbance and reflectance.   
     
     
         9 . A method for estimating a property of a downhole fluid, the method comprising:
 capturing a downhole fluid in a test cell;   introducing electromagnetic energy from a rare earth doped electromagnetic energy source downhole into the downhole fluid in the test cell;   and   detecting electromagnetic energy emitted by the rare earth doped electromagnetic energy source that has interacted with the downhole fluid using an electromagnetic energy detector in electromagnetic energy communication with the downhole fluid for estimating the property of the downhole fluid.   
     
     
         10 . The method of  claim 9 , wherein the electromagnetic energy detector further comprises a photodetector and the rare earth dope electromagnetic energy source further comprises a rare earth doped laser that is selected from at least one of a rare earth doped fiber laser, a rare earth doped silicon on insulator laser and a quantum dot laser. 
     
     
         11 . The method of  claim 10 , wherein the rare earth doped electromagnetic energy pump, rare earth doped laser and photo detector are down hole, the method further comprising:
 adjusting a frequency of the rare earth doped laser to a wavelength of interest using an electro optic modulator for detecting the presence of a chemical of interest in the fluid for estimating the property of the downhole fluid.   
     
     
         12 . The method of  claim 11 , wherein the electro optic modulator device is at least one of a piezoelectric stress tuner, a mechanical stress tuner and a thermal tuner. 
     
     
         13 . The method of  claim 10 , wherein the rare-earth doped laser further comprises a nanocavity in a two-dimensional photonic crystal slab wherein a Q for the rare-earth doped laser is higher than about 1000. 
     
     
         14 . The method of  claim 10 , wherein the rare earth doped electromagnetic energy source further comprises a fiber grating wherein electromagnetic energy from the fiber grating indicates a surrounding medium refractive index for the downhole fluid, wherein the surrounding medium refractive index for the downhole fluid is used in estimating the property of the downhole fluid. 
     
     
         15 . The method of  claim 10 , the method further comprising:
 sending electromagnetic energy into the test cell from an electromagnetic energy pump to the rare earth doped electromagnetic energy source through a window in the test cell, wherein the electromagnetic energy pump is located outside of the test cell.   
     
     
         16 . The method of  claim 10 , wherein the electromagnetic energy that has interacted with the fluid is at least one of electromagnetic energy that has passed through the fluid and electromagnetic energy that has reflected off of the fluid, the method further comprising:
 analyzing the electromagnetic energy that has interacted with the fluid for at least one of transmittance, fluorescence, absorbance and reflectance; and   estimating the property of the downhole fluid.   
     
     
         17 . A method for estimating a property of a downhole fluid, the method comprising:
 traversing a well bore using a carrier attached to a test cell;   introducing a downhole fluid into the test cell;   introducing electromagnetic energy from a rare earth doped electromagnetic energy source downhole into the downhole fluid in the test cell;   and   detecting electromagnetic energy that has interacted with the fluid with an electromagnetic energy source in electromagnetic communication with the downhole fluid for estimating the property of the downhole fluid.   
     
     
         18 . The method of  claim 17 , wherein the electromagnetic energy source further comprises a rare-earth doped laser that is one of a rare earth doped fiber laser, a rare earth doped silicon on insulator laser and a quantum dot laser. 
     
     
         19 . The method of  claim 18 , wherein at least two of the electromagnetic energy source, the rare earth doped laser and the photo detector are down hole, the method further comprising:
 adjusting a frequency of electromagnetic energy output from the electromagnetic energy source to a wavelength of interest using an electro optic modulator for estimating a property of the fluid.   
     
     
         20 . The method of  claim 19 , wherein the rare earth doped electromagnetic energy source further comprises a fiber grating wherein electromagnetic energy from the fiber grating indicates a surrounding medium refractive index for the downhole fluid, wherein the surrounding medium refractive index for the downhole fluid is used in estimating the property of the downhole fluid.