Method for estimating a quantity of a hydrocarbon in mud recovered from a well, and a device and program using the method

Abstract

A method for estimating a concentration of a hydrocarbon in mud recovered from a well includes acquiring a measurement representative of a concentration of the hydrocarbon in mud. An indicator of drill bit metamorphism in the mud is estimated. At least one measurement representative of the concentration of the hydrocarbon in the mud is corrected based on the indicator of drill bit metamorphism.

1 . A method for estimating a concentration of a hydrocarbon in mud recovered from a well penetrating a formation, implemented in an estimation device ( 2 ), comprising:
 acquiring ( 110 ) a measurement representative of a concentration of the hydrocarbon in the mud;   estimating ( 120 ) an indicator of drill bit metamorphism in the mud; and   correcting ( 130 ) at least one measurement representative of the concentration of the hydrocarbon in the mud, based on the indicator of drill bit metamorphism (DBM).   
     
     
         2 . The method according to  claim 1 , wherein acquiring ( 110 ) comprises acquiring a first measurement (C X,AN,LOG ) of a concentration of a first hydrocarbon present in the formation and acquiring a second measurement (C X,EN,LOG ) of a concentration of DBM indicating compound generated by DBM, the first hydrocarbon and the DBM indicating compound being distinct. 
     
     
         3 . The method according to  claim 2 , wherein the indicator of DBM in the mud is an estimated concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM. 
     
     
         4 . The method according to  claim 3 , wherein estimating an indicator of DBM in the mud comprises determining a concentration of the first hydrocarbon produced by DBM from a concentration cross-plot and the second measurement (C X,EN,LOG ), and wherein determining comprises using a regression curve relating the concentration (C X,EN,LOG ) of the DBM indicating compound in the mud to estimate a concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM obtained from the concentration cross-plot. 
     
     
         5 . The method according to  claim 4 , wherein the concentration of the first hydrocarbon is a concentration (C X,AN,LOG ) of an alkane or benzene in the mud, and wherein the estimating ( 120 ) comprises determining a concentration of methane (C 1,AN,DBM ), ethane (C 2,AN,DBM ), propane (C 3,AN,DBM ), butane (C 4,AN,DBM ), pentane (C 5,AN,DBM ), or benzene (C 6,AN,DBM ) produced by drill bit metamorphism from the concentration cross-plot(s). 
     
     
         6 . The method according to  claim 4 , wherein the estimating ( 120 ) comprises estimating a concentration of butane (C 4,AN,DBM ) and/or a concentration of pentane (C 5,AN,DBM ) produced by DBM from a projection curve interpolating estimated concentrations of methane (C 1,AN,DBM ), ethane (C 2,AN,DBM ), and/or propane (C 3,AN,DBM ) produced by DBM. 
     
     
         7 . The method according to  claim 6 , wherein correcting ( 130 ) the measurement representative of the concentration of the hydrocarbon in the mud comprises subtracting the estimated concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM from the first measurement (C X,AN,LOG ). 
     
     
         8 . The method according to  claim 7 , wherein the acquiring ( 110 ) further comprises acquiring a third measurement (δ 13 C X,EX,MES ) of an isotope signature of the hydrocarbon in the mud, and a fourth measurement (δ 13 C X,OBM,MES ) of an isotope signature of the hydrocarbon in the mud prior to being used in the well, and wherein the correcting ( 130 ) comprising correcting the third measurement (δ 13 C X,EX,MES ) based on: the fourth measurement (δ 13 C X,OBM,MES ), the corrected measurement (C X,AN,COR ) representative of the concentration of the hydrocarbon in the mud, the first measurement (C X,AN,LOG ), and the indicator of DBM (C X,AN,DBM ). 
     
     
         9 . The method according to  claim 2 , wherein the acquiring ( 110 ) further comprises acquiring a third measurement (δ 13 C X,EX,MES ) of an isotope signature of the hydrocarbon in the mud, and a fourth measurement (δ 13 C X,OBM,MES ) of an isotope signature of the hydrocarbon in the mud prior to being used in the well. 
     
     
         10 . The method according to  claim 9 , wherein the indicator of DBM in the mud is an estimated isotope signature (δ 13 C X,f ) of the hydrocarbon in the geological formation. 
     
     
         11 . The method according to  claim 10 , wherein estimating ( 120 ) an indicator of DBM comprises calculating the estimated isotope signature (δ 13 C X,f ) from an isotopic cross-plot of the third measurement (δ 13 C X,EX,MES ), versus a ratio calculated from the first (C X,AN,LOG ) and the second (C X,EN,LOG ) measurements. 
     
     
         12 . The method according to  claim 11 , wherein estimating ( 120 ) an indicator of drill bit metamorphism further comprises calculating from a generative curve, an isotope signature (δ 13 C X,f ) of the hydrocarbon in the mud recovered from the drilling at the point where the concentration of the DBM indicating compound is zero. 
     
     
         13 . The method according to  claim 12 , wherein the correcting ( 130 ) comprises computing an estimated concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM as a function of the third measurement (δ 13 C X,EX,MES ), the fourth measurement (δ 13 C X,OBM,MES ), and the indicator of DBM (δ 13 C X,f ). 
     
     
         14 . The method according to  claim 13 , wherein the correcting ( 130 ) comprises subtracting the estimated concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM, from the first measurement (C X,AN,LOG ). 
     
     
         15 . The method according to  claim 14 , wherein the first hydrocarbon is an alkane and the DBM indicating compound is an alkene, carbon monoxide, and/or hydrogen. 
     
     
         16 . The method according to  claim 14 , wherein the first hydrocarbon is benzene and the DBM indicating compound is an alkene, carbon monoxide, and/or hydrogen. 
     
     
         17 . The method according to  claim 14 , wherein the correcting ( 130 ) comprises a calculation of an estimation of a concentration of at least a hydrocarbon in the formation. 
     
     
         18 . A computer program product comprising software instructions which, when implemented by a piece of computer equipment, carry out the method for estimating a concentration of at least a hydrocarbon according to  any one of the preceding claims . 
     
     
         19 . An estimation device ( 2 ) for estimating a concentration of a hydrocarbon in mud recovered from a well, the estimation device ( 2 ) comprising:
 an acquisition unit ( 56 ) configured to acquire a measurement representative of a concentration of the hydrocarbon in the mud;   an estimation unit ( 58 ) configured to estimate an indicator of drill bit metamorphism (DBM) in the mud; and   a correction unit ( 60 ) configured to correct the measurement representative of the concentration of the hydrocarbon in the mud, based on the indicator of DBM.   
     
     
         20 . The estimation device ( 2 ) of  claim 19 , wherein:
 the acquisition unit ( 56 ) is configured to acquire a first measurement (C X,AN,LOG ) of a concentration of a first hydrocarbon present in the mud and a second measurement (C X,EN,LOG ) of a concentration of DBM indicating compound generated by DBM, the first hydrocarbon and the DBM indicating compound being distinct;   the estimation unit ( 58 ) is configured to determine a concentration of the first hydrocarbon produced by DBM from a concentration cross-plot and the second measurement (C X,EN,LOG ), wherein the determining comprises using a regression curve relating the concentration (C X,EN,LOG ) of the DBM indicating compound in the mud to estimate a concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM obtained from the concentration cross-plot; and   the correction unit is configured to subtract the estimated concentration (C X,AN,DBM ) of the first hydrocarbon produced by DBM from the first measurement (C X,AN,LOG ) of the concentration of the first hydrocarbon present in the mud.