System and method for determining natural hydrocarbon concentration utilizing isotope data

A method to measure a concentration of natural methane in a sample of drilling fluid, the method comprising:

• determining a δ13C isotopic signature of a first hydrocarbon component in the sample;
• determining a δ13C isotopic signature of a second hydrocarbon component in the sample;
• determining a δ13C isotopic signature of methane in the sample, the methane comprising natural methane originating from the earth formation and artificially-produced methane caused by drill bit metamorphism (DBM);
• and
• determining, using a processor, the concentration of the natural methane in the sample based on the δ13C isotopic signature of the first hydrocarbon component, the δ13C isotopic signature of the second hydrocarbon component, and the δ13C isotopic signature of the methane.

A system to measure a natural concentration of methane in a sample of drilling fluid, the system comprising:

• at least one processor;
• and
• a memory including instructions that, when executed by the at least one processor, cause the system to:
• determine a δ13C isotopic signature of a first hydrocarbon component in the sample;
• determine a δ13C isotopic signature of a second hydrocarbon component in the sample;
• determine a δ13C isotopic signature of methane in the sample, the methane comprising natural methane originating from the earth formation and artificially-produced methane caused by drill bit metamorphism;
• and
• determine the concentration of the natural methane in the sample based on the δ13C isotopic signature of the first hydrocarbon component, the δ13C isotopic signature of the second hydrocarbon component, and the δ13C isotopic signature of the methane.