Reservoir depletion assessment while drilling

Abstract

Implementations described and claimed herein provide systems and methods for assessment of reservoir depletion based on mud gas geochemistry while a well is being drilled and to assist in optimizing development and production strategies with faster turnaround and lower cost. Contrary to drilling one or more test wells to determine the depletion of the reservoir, mud gas geochemistry data is readily available, real-time, and low cost. In some particular implementations, a total hydrocarbon gas intensity and/or detailed hydrocarbon gas compositions may be analyzed and function together as a reliable indicator of reservoir pressure and in-place petroleum fluids quality. The mud gas geochemistry data may be interpreted in the context of in-place petroleum fluids properties (e.g., maturity, bulk and isotope compositions, and PVT phase behaviors), with the aids of mud logging and production data from nearby wells if available, to evaluate reservoir depletion.

What is claimed is: 
     
         1 . A method for assessment of depletion of a reservoir, the method comprising:
 receiving, from a well being drilled, one or more mud gas samples from the well;   determining, by a geofluid spectrometer, at least one geochemical parameter of the one or more mud gas samples, wherein the at least one geochemical parameter comprises a total hydrocarbon gas intensity of the one or more mud gas samples; and   assessing a depletion of a target reservoir of the well based at least on the at least one geochemical parameter of the one or more mud gas samples.   
     
     
         2 . The method of  claim 1  further comprising:
 obtaining, using a processing device, offset well production data, wherein the assessing the depletion of the target reservoir of the well is further based on the offset well production data. 
 
     
     
         3 . The method of  claim 1  further comprising:
 obtaining, using a processing device, a location of an offset well relative to a location of the well being drilled, wherein the assessing the depletion of the target reservoir of the well is further based on the location of the offset well and a duration the offset well has been producing. 
 
     
     
         4 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a concentration of C1 of the one or more mud gas samples. 
     
     
         5 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a concentration of C2 of the one or more mud gas samples. 
     
     
         6 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a concentration of C3 of the one or more mud gas samples. 
     
     
         7 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises concentrations of iC4 and nC4 of the one or more mud gas samples. 
     
     
         8 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises concentrations of iC5 and nC5 of the one or more mud gas samples. 
     
     
         9 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises concentrations of nC6, cyclo-hexane (CH) and benzene of the one or more mud gas samples. 
     
     
         10 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises concentrations of nC7, methyl cyclo-hexane (MCH) and toluene of the one or more mud gas samples. 
     
     
         11 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises concentrations of non-hydrocarbon gases, CO 2 , or H 2 S, of the one or more mud gas samples. 
     
     
         12 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a mud gas balance ratio and a wetness ratio of the one or more mud gas samples. 
     
     
         13 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a C1 to C3 ratio of the one or more mud gas samples. 
     
     
         14 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a ratio of benzene to nC6 of the one or more mud gas samples. 
     
     
         15 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a ratio of toulene to nC7 of the one or more mud gas samples. 
     
     
         16 . The method of  claim 1 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a water saturation parameter determined from a ratio of MCH to nC7 and a ratio of toluene to nC7 of the one or more mud gas samples. 
     
     
         17 . The method of  claim 1  further comprising:
 displaying, in a user interface, the assessment of the depletion of the target reservoir. 
 
     
     
         18 . A system for assessment of depletion of a reservoir, the system comprising:
 a mud sample extraction device; and   a reservoir depletion assessment platform including an application to:
 receive, from mud sample extraction device, one or more mud gas samples from the well; 
 generate, based on at least one geochemical parameter of the one or more mud gas samples, an assessment of a depletion of a target reservoir of the well, wherein the at least one geochemical parameter comprises a total hydrocarbon gas intensity of the one or more mud gas sample; and 
 assess a depletion of a target reservoir of the well based at least on the at least one geochemical parameter of the one or more mud gas samples. 
   
     
     
         19 . The system of  claim 18 , wherein the application is further to:
 obtain offset well production data, wherein the assessing the depletion of the target reservoir of the well is further based on the offset well production data.   
     
     
         20 . The system of  claim 18 , wherein the application is further to:
 obtain a location of an offset well relative to a location of the well being drilled, wherein the assessing the depletion of the target reservoir of the well is further based on the location of the offset well and a duration the offset well has been producing.   
     
     
         21 . The system of  claim 18 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a mud gas balance and a wetness variable of the one or more mud gas samples. 
     
     
         22 . The system of  claim 18 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a concentration of C1 of the one or more mud gas samples. 
     
     
         23 . The system of  claim 18 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a concentration of C2 of the one or more mud gas samples. 
     
     
         24 . The system of  claim 18 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a concentration of C3 of the one or more mud gas samples. 
     
     
         25 . The system of  claim 18 , wherein the at least one geochemical parameter of the one or more mud gas samples further comprises a water saturation parameter determined from a ratio of MCH to nC7 and a ratio of toluene to nC7 of the one or more mud gas samples. 
     
     
         26 . The system of  claim 18 , wherein the application is further to:
 display, in a user interface, the assessment of the depletion of the target reservoir.