Applications of advanced isotope geochemistry of hydrocarbons and inert gases to petroleum production engineering

1. A method for enhancing hydrocarbon production comprising:

obtaining a first sample comprising hydrocarbons from a target subsurface interval of a reservoir;

analyzing the first sample for a geochemical signature, wherein the geochemical signature comprises a clumped isotope signature and/or a position specific isotope signature for a hydrocarbon compound of interest in the first sample;

converting the clumped isotope signature and/or the position specific isotope signature of the hydrocarbon compound of interest to a temperature for the first sample;

obtaining a second sample comprising hydrocarbons from the target subsurface interval of the reservoir, wherein the second sample is obtained at a time later than the first sample;

analyzing the second sample for a geochemical signature, wherein the geochemical signature comprises a clumped isotope signature and/or a position specific isotope signature for the hydrocarbon compound of interest in the second sample;

converting the clumped isotope signature and/or the position specific isotope signature of the hydrocarbon compound of interest to a temperature for the second sample;

comparing the temperatures of the first and second samples;

determining whether the hydrocarbons in the second sample originated from the target subsurface interval or from a different interval in the reservoir, wherein the determination is based at least in part on the comparison of the temperatures of the first and second samples;

adjusting a recovery strategy for the reservoir based on the determination; and

producing hydrocarbons from the reservoir based on the adjusted recovery strategy.

2. The method of claim 1 , wherein analyzing the first or second sample for the geochemical signature further comprises determining a noble gas signature.

3. The method of claim 2 , further comprising determining differences between the noble gas signatures for the first and second samples.

4. The method of claim 1 , wherein the determination involves analyzing each of the first and second samples to identify a source contribution for each of the first and second samples.

5. The method of claim 1 , further comprising monitoring the geochemical signature of a plurality of samples during production for changes in the source contribution for each of the plurality of samples.

6. The method of claim 5 , wherein the source contribution comprises determining fracture flow versus matrix flow.

7. The method of claim 6 , wherein fracture flow is movement of reservoir fluids through natural or induced fractures or fracture networks in the rock and matrix flow is movement of reservoir fluids through the rock fabric.

8. The method of claim 1 , further comprising quantifying a total in-place hydrocarbons from a source contribution of the respective hydrocarbon sample.

9. The method of claim 1 , further comprising:

obtaining at least one external sample of stray fluids in one of a well annuli and/or surrounding strata;

analyzing at least one external sample for an external geochemical signature comprising a clumped isotope signature and/or position specific isotope signature;

comparing the external geochemical signature with the geochemical signatures from the first or second hydrocarbon samples;

determining a source interval for the at least one external sample based on the comparison; and

developing a mitigation strategy based on the determination.

10. The method of claim 9 , further comprising:

introducing an exotic clumped isotope spike into one of the target interval or a wellbore that provides fluid communication to the target interval;

analyzing the at least one external sample for the exotic clumped isotope spike; and

developing a mitigation strategy based on the analysis.

11. The method of claim 10 , wherein the exotic clumped isotope spike is a form of pure 13 CD 4 .

12. The method of claim 1 , wherein determining whether the hydrocarbons in the sample originated from the target subsurface interval or from a different interval, comprises comparing the determined temperature of the hydrocarbon sample with an expected temperature for the target subsurface interval.

13. A method for enhancing hydrocarbon production comprising:

obtaining one or more samples comprising hydrocarbons from one or more target subsurface intervals of a reservoir, wherein the target subsurface intervals are the subsurface intervals which are intended to be produced during production operations;

analyzing the one or more samples for a target geochemical signature, wherein the target geochemical signature comprises a clumped isotope signature and/or a position specific isotope signature for a hydrocarbon compound of interest in the one or more samples;

converting the clumped isotope signature and/or the position specific isotope signature of the hydrocarbon compound of interest to a temperature for the one or more samples;

obtaining at least one external sample of stray fluids from one of a well annuli and/or surrounding strata;

analyzing the at least one external sample for an external geochemical signature comprising a clumped isotope signature and/or position specific isotope signature of a hydrocarbon compound of interest in the external sample;

comparing the external geochemical signature with the target geochemical signature;

determining a source interval for the at least one external sample based on the comparison;

developing a mitigation strategy for the reservoir based on the determination; and

producing hydrocarbons from the reservoir based at least in part on the mitigation strategy.