Site analysis system for the calculation of the isotope ratio of carbon in several gas species by means of a single analyser

Abstract

The present invention relates to a system of analysis, which can be used in a mobile laboratory in a drilling site situation or in a similar situation, suitable for measuring (preferably in relation to at least two partially gaseous species, which derive preferably from a mixture extracted from a drilling mud, for example, methane, ethane, propane and/or any other heavier hydrocarbons) the quantities of the different isotopes of at least a same chemical element (preferably the quantities of 13 C, carbon isotope with 6 protons and 7 neutrons, and of 12 C, carbon isotope with 6 protons and 6 neutrons, respectively) by means of a laser isotopes analyser regulated for a single, at least partially gaseous species which contains said chemical element.

1 . A system of analysis, which is able to at least partially measure the isotopic content of at least a chemical element, also as a continuous process on site and in relation to at least two different at least partially gaseous species containing that element, said species being contained in at least one at least partially gaseous mixture, which in turn was originally extracted, preferably but not exclusively, from a drilling mud, wherein said system comprises:
 at least one gas chromatograph for the mutual separation of said gaseous species;   at least one oxidation oven for heating said gaseous species separately and consequently producing at least one other at least partially gaseous species; and   at least one laser isotopes analyser configured to analyse said gaseous species produced by heating.   
     
     
         2 . The system of analysis according to  claim 1 , wherein the system comprises at least one processor suitable for controlling at least part of the components of said system. 
     
     
         3 . The System of analysis according to  claim 2 , wherein the system comprises at least the following components, which possibly are at least partially controlled by said processor:
 means for transferring each of said gaseous species to be analysed, from said gas chromatograph to said oxidation oven;   means for transferring said gaseous species produced by heating, from said oxidation oven to said laser isotopes analyser; and   means for collecting and concentrating said gaseous species produced by heating before isotope analysis.   
     
     
         4 . The system of analysis according to  claim 2 , wherein the system is configured to be usable with a process which comprises a sequence formed at least by the following steps, at least partially controlled by said processor and whereof at least two steps can be at least partially simultaneous:
 a) at least part of at least one at least partially gaseous mixture enters said gas chromatograph;   b) said part of said mixture is at least partially separated into at least two portions, at least one at least partially gaseous species contained in one of these portions being different from at least one at least partially gaseous species contained in the other of said portions;   c) at least part of at least one of said portions enters said oxidation oven;   d) said oxidation oven heats said part of said portion, and then generates at least one at least partially gaseous species;   e) at least part of the latter generated species enters said laser analyser, which analyses the isotope content relative to at least one chemical element which constitutes at least a part of the same generated species; and   f) steps c) , d), e), are repeated for at least another one of said portions.   
     
     
         5 . The system of analysis according to  claim 4 , wherein:
 said oxidation oven transforms said gas species to be analysed, at least into carbon dioxide CO 2 ;   said laser isotopes analyser is configured to analyse the isotopes of the carbon contained in the carbon dioxide CO 2 ; and   said gas chromatograph is connected to at least one flame ionization detector, or FID, to measure the times of retention of the gas species and to calibrate the system.   
     
     
         6 . The system of analysis according to  claim 3 , wherein the system is configured to be usable with a process which comprises the sequence formed at least by the following steps, at least partially controlled by said processor and in which at least two steps can be at least partially simultaneous:
 a) at least part of at least one at least partially gaseous mixture enters said gas chromatograph;   b) said part of said mixture is at least partially separated into at least two portions, at least one at least partially gaseous species contained in one of these portions being different from at least one at least partially gaseous species contained in the other of said portions;   c) at least part of at least one of said portions enters said oxidation oven;   d) said oxidation oven heats said part of said portion, and then generates at least one at least partially gaseous species;   e) at least part of the latter generated species enters said laser analyser, which analyses the isotope content relative to at least one chemical element which constitutes at least a part of the same generated species; and   f) steps c) , d), e), are repeated for at least another one of said portions.   
     
     
         7 . The system of analysis according to  claim 6 , wherein:
 said oxidation oven transforms said gas species to be analysed, at least into carbon dioxide CO 2 ;   said laser isotopes analyser is configured to analyse the isotopes of the carbon contained in the carbon dioxide CO 2 ; and   said gas chromatograph is connected to at least one flame ionization detector, or FID, to measure the times of retention of the gas species and to calibrate the system.   
     
     
         8 . The system of analysis according to  claim 1 , wherein said gas chromatograph comprises at least:
 one valve, or “sample valve;   one conduit for the entry of at least a carrier gas, or “primary entry line,” and connected to at least one way of said sample valve;   one other conduit for the entry of the gaseous mixture to be analysed, or “gas entry line,” and connected to at least one way of said sample valve;   one other conduit which performs the function of chromatographic column, or “backwashing column,” and connected to at least two ways of said sample valve;   one other conduit, or “sampling cell,” and connected to at least two ways of said sample valve;   one other conduit, or “intermediate line,” and connected to at least one way of said sample valve;   one other conduit for the discharge of gas, connected to at least one way of said sample valve; and   said sample valve being able to place in contact at least:
 said sampling cell at least with said gas entry line and a discharge conduit, or said sampling cell at least with said backwashing column and said primary entry line; 
 said backwashing column at least with said primary entry line and with a discharge conduit, or said backwashing column at least with said intermediate line and said sampling cell; and 
 said gas entry line at least with said sampling cell or at least with a discharge conduit. 
   
     
     
         9 . The system of analysis according to  claim 8 , wherein the system is configured with adequate means so as to allow said chromatograph to operate according to a process which comprises at least the sequence formed by the following steps, at least partially controlled by said processor, which in turn is preferably manually calibrated by the user, and whereof at least two steps can be at least partially simultaneous:
 at least part of an at least partially gaseous mixture, arriving from the entry line for the gas, flows at least partially through the sampling cell and moves towards a discharge conduit;   said sample valve changes configuration so as to place said primary entry line in contact with said sampling cell;   at least a carrier gas enters at least partially the sampling cell, taking from the sampling cell said part of the mixture, and draws the latter at least partially into the backwashing column;   two or more at least partially gaseous species of said mixture are at least partially separated, or moved away, between them and within said backwashing column;   at least a carrier gas starts to draw at least two of said gaseous species, a “first species” and a “second species,” and are preferably the lighter components of said part of the mixture, at least partially inside said intermediate line; and   after the heaviest species to be analysed has at least partially entered said intermediate line, the sample valve once again changes configuration, so as to prevent at least partially at least one heavier species from entering said intermediate line.   
     
     
         10 . The system of analysis according to  claim 8 , wherein said gas chromatograph comprises at least:
 one other valve, or “storage valve”;   said intermediate line being connected to at least one way of said storage valve;   one other conduit, or “store column”, connected to at least two ways of said storage valve;   said store column performing the function of a chromatographic column;   one other conduit, or “connection line,” connected to at least one way of said storage valve; and   said storage valve being able to place in contact at least:
 said store column at least with said intermediate line and said connection line, or said store column at least with two at least partially closed sections. 
   
     
     
         11 . The system of analysis according to  claim 10 , wherein the system is configured with adequate means so as to allow said chromatograph to be able to operate according to a process which comprises at least the sequence formed by the following steps, at least partially controlled by said processor, which in turn is preferably manually calibrated by the user, and whereof at least two steps can be at least partially simultaneous:
 at least one carrier gas draws said first and second species to be analyzed at least partially through said intermediate line and subsequently inside said store column, where the latter two species preferably at least partially move away even more between them;   at least said first species exits at least partially from said store column, while said storage valve places in contact said store column with said connection line, and enters at least partially said connection line; and   said storage valve changes configuration so as to place said store column in contact with said two closed sections so that at least said second species remains at least partially trapped inside said store column.   
     
     
         12 . The system of analysis, which can be used in a mobile laboratory in a drilling site situation according to  claim 10 , wherein said gas chromatograph comprises at least:
 one other valve, or “final valve”;   said connection line being connected to at least one way of said final valve;   one other conduit, or “holding chamber,” connected to at least two ways of said final valve;   one other conduit for the discharge of gas, connected to at least one way of said final valve;   one other conduit for the entry of the carrier gas, or “secondary entry line,” connected to at least one way of said final valve; and   one other conduit, or “exit line”, for the exit of each gas species travelling towards said oxidation oven, said exit line being connected to at least one way of said final valve;   said final valve being able to place in contact at least:
 said holding chamber at least with said connection line and a discharge conduit, or said holding chamber at least with said secondary entry line and said exit line; and 
 said connection line at least with said holding chamber, or at least with a discharge conduit. 
   
     
     
         13 . The system of analysis according to  claim 12 , wherein the system is configured with adequate means so as to allow said chromatograph to operate according to a process which comprises at least a sequence formed by the following steps, at least partially controlled by said processor, which in turn is preferably manually calibrated by the user, and whereof at least two can steps be at least partially simultaneous:
 at least one carrier gas draws at least said first species at least partially through said connection line, and subsequently at least partially inside said holding chamber, while said final valve places said holding chamber in contact with said connection line;   said final valve changes configuration so as to place said holding chamber in contact with said secondary entry line;   at least one carrier gas, in arrival from said secondary entry line, flows at least partially through said holding chamber, taking said first species and conveying said first species at least partially into said exit line;   said storage valve changes configuration so as to place said store column in contact with said connection line so that said second species exits at least partially from said store column, and enters at least partially said connection line; and   at least one carrier gas draws at least said second species at least partially through said connection line, and subsequently at least partially inside said holding chamber, while said final valve again places said holding chamber in contact with said connection line;   said final valve changes configuration so as to place said holding chamber in contact with said secondary entry line; and   at least one carrier gas, in arrival from said secondary entry line, flows at least partially through said holding chamber, taking said second species and conveying said second species at least partially into said exit line.   
     
     
         14 . The system of analysis according to  claim 13 , wherein the system is synchronized so that, separately and sequentially, for each single species of said at least two species:
 the single species flows at least partially through said exit line, enters said oxidation oven and is heated so as to produce at least carbon dioxide;   the carbon dioxide produced by the heating of said single species is collected and concentrated by known means; and   said isotope analyzer detects the isotopic content of the carbon contained in said carbon dioxide, which is derived from said single species.   
     
     
         15 . The system of analysis according  claim 14 , wherein said processor controls at least said gas chromatograph, and said changes of configuration of the valves are controlled by said software at instants of times programmed, preferably manually, by the user.