Novel well logging method for the determination of catalytic activity

Abstract

The present invention relates to assays for ascribing catalytic activity to rock samples by virtue of zero-valent transition metals potentially being present within the sample. Embodiments of the present invention are generally directed to novel assays for measuring intrinsic paleocatalytic activities (k) of sedimentary rocks for converting oil to gas and projecting the activities to the subsurface based on the measured linear relationship between ln(k) and temperature (T).

1 . A well logging method comprising: 
 a) obtaining sedimentary rock samples during the course of well logging, wherein said sedimentary rock sample potentially comprises zero-valent transition metal; and    b) analyzing said sedimentary rock samples by a method comprising: 
 i) a sample preparation step for exposing fresh surface of a quantity of the sedimentary rock sample;  
 ii) a reaction step for exposing the sedimentary rock sample to hydrogen gas and a hydrocarbon material in an exposure environment under assay exposure conditions, the hydrocarbon material comprising hydrocarbon species having two or more carbons and wherein said exposure leads to the catalytic generation of methane gas if zero-valent transition metal is present within the sedimentary rock sample; and  
 iii) an analysis step for ascertaining the presence of methane catalytically-generated by zero-valent transition metal potentially present in said rock sample and, if present, for ascribing an intrinsic catalytic activity to said sedimentary rock,  
   wherein said analyzing yields a well log with intrinsic catalytic rock activity as a function of well depth.    
   
   
       2 . The well logging method of  claim 1 , wherein the sample preparation step of said analyzing involves a grinding process for exposing fresh surface of a quantity of sedimentary rock sample.  
   
   
       3 . The well logging method of  claim 1 , wherein the sample preparation step of said analyzing is carried out under inert conditions.  
   
   
       4 . The well logging method of  claim 1 , wherein the exposure environment of the reaction step of said analyzing is carried out under conditions selected from the group consisting of static, flow, and combinations thereof.  
   
   
       5 . The well logging method of  claim 1 , wherein the assay exposure conditions of said analyzing method comprise a temperature of between about 200° C. and about 450° C., and a hydrogen partial pressure of between about 0.1 torr and about 500 torr.  
   
   
       6 . The well logging method of  claim 1 , wherein the reaction step of said analyzing method comprises a duration of between about 1 minute and about 30 days.  
   
   
       7 . The well logging method of  claim 1 , wherein the hydrocarbon material used in the reaction step of said analyzing method comprises hydrocarbon species having 2-25 carbon atoms.  
   
   
       8 . The well logging method of  claim 1 , wherein said analyzing method further comprises a separation step for separating any catalytically-generated methane from any other hydrocarbon species potentially present after the reaction step, wherein said separating is done by a method selected from the group consisting of condensing the other hydrocarbon species on a cold trap, chromatographic means, and combinations thereof.  
   
   
       9 . The well logging method of  claim 1 , wherein the analysis step of said analyzing method involves detecting the presence of catalytically-generated methane using a detection device selected from the group consisting of a flame ionization detector, a mass-selective detector, a spectroscopic detector, an electron capture detector, a thermal conductivity detector, a residual gas analyzer, and combinations thereof.  
   
   
       10 . The well logging method of  claim 1 , wherein ascribing an intrinsic catalytic activity to said sedimentary rock in the analysis step of said analyzing method further comprises determining a rate constant, k, associated with a given set of reaction conditions and a reaction duration, as utilized in the reaction step.  
   
   
       11 . A well logging method comprising: 
 a) obtaining sedimentary rock samples potentially comprising a quantity of at least one zero-valent transition metal during the course of well logging; and    b) analyzing said sedimentary rock samples by a method comprising the steps of: 
 i) processing the sedimentary rock sample to provide freshly exposed surface;  
 ii) exposing the sedimentary rock sample to hydrogen gas and a quantity of hydrocarbon material in an exposure environment under a set of assay exposure conditions, the hydrocarbon material comprising hydrocarbon species having at least two carbons, such that methane is catalytically generated if zero-valent transition metal is present within the sedimentary rock sample; and  
 iii) analyzing the exposure environment for any catalytically-generated methane, generated as a result of said exposing, in order to ascertain the presence of zero-valent transition metal within said sedimentary rock sample and, if present, ascribing an intrinsic catalytic activity to the sedimentary rock for the set of assay exposure conditions,  
   wherein said analyzing yields a well log with intrinsic catalytic rock activity as a function of well depth.    
   
   
       12 . The well logging method of  claim 11 , wherein the processing step involves a grinding process for exposing fresh surface of the sedimentary rock sample.  
   
   
       13 . The well logging method of  claim 11 , wherein the processing step is carried out under inert conditions.  
   
   
       14 . The well logging method of  claim 11 , wherein the exposure environment is selected from the group consisting of a static system, a flow system, and combinations thereof.  
   
   
       15 . The well logging method of  claim 11 , wherein the assay exposure conditions comprise a temperature of between about 200° C. and about 350° C., and a hydrogen partial pressure of between about 0.1 torr and about 500 torr.  
   
   
       16 . The well logging method of  claim 11 , wherein the step of exposing comprises a duration of between about 1 minute and 30 days.  
   
   
       17 . The well logging method of  claim 11 , wherein the hydrocarbon material used in the exposing step comprises hydrocarbon species having 2-25 carbon atoms.  
   
   
       18 . The well logging method of  claim 11 , further comprising a step of separating any catalytically-generated methane from any other hydrocarbon species potentially present after the exposing step, wherein the separating is done by a method selected from the group consisting of condensing the other hydrocarbon species on a cold trap, a chromatographic means, and combinations thereof.  
   
   
       19 . The well logging method of  claim 11 , wherein the step of analyzing involves detecting the presence of catalytically-generated methane using a detection device selected from the group consisting of a flame ionization detector, a mass-selective detector, a spectroscopic detector, an electron capture detector, a thermal conductivity detector, a residual gas analyzer, and combinations thereof.  
   
   
       20 . The well logging method of  claim 11 , wherein ascribing an intrinsic catalytic activity to said sedimentary rock in the step of analyzing further comprises determining a rate constant, k, associated with a given set of reaction conditions and a reaction duration, as utilized in the reaction step.