Mud logging depth and composition measurements

Abstract

A sample that includes formation content from a subsurface formation and other sample constituents is obtained while the sample is in close proximity to the subsurface formation. While downhole, the formation content is separated from the other sample constituents by passing the sample through an oil-wet porous plate, a water-wet porous plate, or through both plates, and analyzed. Various petrophysical properties of the formation content may be determined. To further separate the formation content, one may pass the sample through a mesh, pass the sample into an expansion chamber, or draw the sample into a chamber using a moveable piston. The formation content may be analyzed downhole using, for example, a mass spectrometer, FTIR, or chromatograph. The hydrocarbon contribution from oil based drilling fluid can be accounted for. Alternatively, a capsule may be charged with “live” formation content and conveyed uphole to be analyzed.

What is claimed is: 
     
         1 . A method, comprising:
 obtaining a sample comprising formation content from a subsurface formation and other sample constituents while the sample is in close proximity to the subsurface formation;   separating downhole the formation content from the other sample constituents by at least passing the sample through an oil-wet porous plate, a water-wet porous plate, or through both the oil-wet porous plate and the water-wet porous plate;   analyzing downhole the formation content; and   determining petrophysical properties of the formation content.   
     
     
         2 . The method of  claim 1 , wherein the separating downhole the formation content further comprises one or more of: passing the sample through a mesh, passing the sample into an expansion chamber, and drawing the sample into a chamber using a moveable piston. 
     
     
         3 . The method of  claim 1 , wherein the analyzing downhole the formation content comprises using one or more devices selected from the group consisting of: a mass spectrometer, a Raman spectrometer, an infrared spectrometer, an ultraviolet or visible light absorption spectrometer, a Fourier transform spectrometer operating in conjunction with any of the above-listed devices, and a chromatograph. 
     
     
         4 . The method of  claim 1 , wherein the determining petrophysical properties of the formation content comprises determining one or more of: hydrocarbon composition; hydrocarbon quantity; hydrocarbon ratios; identification of productive hydrocarbon-bearing intervals, fluid types, and fluid contacts; ability to identify and assess compartmentalization, both vertical and areal; identification of bypassed/low-resistivity pay; identification of changes in lithology; ability to assess the effectiveness of reservoir seals; identification of the charge history of an accumulation; determining the thermal maturity of the hydrocarbon identified; and geosteering using gas while drilling. 
     
     
         5 . A method, comprising:
 obtaining a sample comprising formation content from a subsurface formation, hydrocarbons from an oil based drilling fluid, and other sample constituents while the sample is in close proximity to the subsurface formation;   
       separating downhole the formation content and the oil based drilling fluid hydrocarbons from the other sample constituents by at least passing the sample through an oil-wet porous plate, a water-wet porous plate, or through both the oil-wet porous plate and the water-wet porous plate;
 analyzing the intermixed formation content and the oil based drilling fluid hydrocarbons; 
 accounting for the presence of the oil based drilling fluid hydrocarbons; and 
 determining petrophysical properties of the formation content. 
 
     
     
         6 . The method of  claim 5 , wherein the separating downhole the formation content further comprises one or more of: passing the sample through a mesh, passing the sample into an expansion chamber, and drawing the sample into a chamber using a moveable piston. 
     
     
         7 . The method of  claim 5 , wherein the analyzing downhole the formation content comprises using one or more devices selected from the group consisting of: a mass spectrometer, a Raman spectrometer, an infrared spectrometer, an ultraviolet or visible light absorption spectrometer, a Fourier transform spectrometer operating in conjunction with any of the above-listed devices, and a chromatograph. 
     
     
         8 . The method of  claim 5 , wherein the determining petrophysical properties of the formation content comprises determining one or more of: hydrocarbon composition; hydrocarbon quantity; hydrocarbon ratios; identification of productive hydrocarbon-bearing intervals, fluid types, and fluid contacts; ability to identify and assess compartmentalization, both vertical and areal; identification of bypassed/low-resistivity pay; identification of changes in lithology; ability to assess the effectiveness of reservoir seals; identification of the charge history of an accumulation; determining the thermal maturity of the hydrocarbon identified; and geosteering using gas while drilling. 
     
     
         9 . The method of  claim 5 , wherein the accounting for the presence of the oil based drilling fluid hydrocarbons comprises analyzing substantially uncontaminated oil based drilling fluid for its hydrocarbon content and subtracting a corresponding hydrocarbon contribution from the results obtained from analyzing the intermixed formation content and the oil based drilling fluid hydrocarbons. 
     
     
         10 . A method, comprising:
 obtaining a sample comprising formation content from a subsurface formation and other sample constituents while the sample is in close proximity to the subsurface formation;   separating downhole the formation content from the other sample constituents by at least passing the sample through an oil-wet porous plate, a water-wet porous plate, or through both the oil-wet porous plate and the water-wet porous plate;   charging one or more capsules with the formation content;   conveying the one or more capsules uphole;   analyzing uphole the formation content; and   determining petrophysical properties of the formation content.   
     
     
         11 . The method of  claim 10 , wherein the charging one or more capsules with the formation content comprises, for each capsule, injecting the formation content into the capsule through a self-sealing membrane and recording within a capsule memory at least depth information corresponding to the obtained sample. 
     
     
         12 . The method of  claim 10 , wherein the conveying the one or more capsules uphole comprises placing the one or more capsules into the wellbore annulus and using drilling fluid to transport the one or more capsules uphole. 
     
     
         13 . The method of  claim 10 , further comprising detecting uphole the one or more capsules using electromagnetic radiation, a liquid of density different from the one or more capsules, or a combination of those. 
     
     
         14 . An apparatus, comprising:
 a downhole tool disposed in a wellbore, the downhole tool having:
 a first sampling chamber in fluid communication with an annular region of the wellbore; 
 a cartridge in fluid communication with the first sampling chamber; wherein a selective fluid barrier is disposed in the cartridge; and 
 one or more downhole instruments to make one or more downhole measurements on a sample. 
   
     
     
         15 . The apparatus of  claim 14 , wherein the selective fluid barrier is selected from a group consisting of an oil-wet porous plate, a water-wet porous plate, and a back-to-back combination of oil-wet and water-wet porous plates. 
     
     
         16 . The apparatus of  claim 14 , further comprising a second sampling chamber, wherein the second sampling chamber comprises:
 a piston disposed in an interior region of the second sampling chamber; and   a motor operatively joined to the piston.   
     
     
         17 . The apparatus of  claim 14 , wherein the first sampling chamber is selectively in fluid communication with an interior region of a drill pipe and the fluid communication between the first sampling chamber and the annular region of the wellbore is selective. 
     
     
         18 . An apparatus, comprising:
 a downhole tool having a sampler, the downhole tool being disposed in a wellbore having fluid therein and the sampler having a selective barrier through which a sample passes; and   one or more capsules carried by the downhole tool, each of the one or more capsules being capable of containing a particular sample produced by the sampler and being releasable into the fluid in the wellbore.   
     
     
         19 . The apparatus of  claim 18 , wherein the sampler comprises:
 a first sampling tube in fluid communication with an annular region of the wellbore; and   a separator in fluid communication with the first sampling tube.   
     
     
         20 . The apparatus of  claim 19 , wherein the separator comprises:
 a first sampling chamber having a first valve to allow or prevent fluid communication between the first sampling chamber and the first sampling tube;   a fluid passageway joining the first sampling chamber to a second sampling chamber and having a second valve to allow or prevent fluid communication between the first sampling chamber and the second sampling chamber; and   wherein the selective barrier is disposed in the fluid passageway.   
     
     
         21 . The apparatus of  claim 20 , wherein the selective barrier is selected from a group consisting of an oil-wet porous plate, a water-wet porous plate, and a back-to-back combination of oil-wet and water-wet porous plates. 
     
     
         22 . The apparatus of  claim 20 , wherein the separator further comprises:
 a piston disposed in an interior region of the second sampling chamber; and   a motor operatively joined to the piston.   
     
     
         23 . The apparatus of  claim 18 , wherein each of the one or more capsules has an antenna. 
     
     
         24 . The apparatus of  claim 18 , wherein each of the one or more capsules has a self-sealing membrane through which the particular sample may be injected into an interior region of the capsule. 
     
     
         25 . The apparatus of  claim 18 , wherein each of the one or more capsules has a memory device.