Natural Gas - Isodetect

Isotope studies to evaluate natural gas storage facilities and deposits

The isotope values (¹³C, ²H) of methane, lower alkanes, condensates and other hydrocarbons provide important insights into the degree of maturity and the origin of natural gas or petroleum. This information is important for the development of deposits, but also for the use of underground storage facilities (sediments, caverns).

The process dynamics in the deposits can be decoded and evaluated with special diagrams (e.g. Whiticair diagram). To do this, simply send us gas samples from the various depths and areas.

Bernard diagram for distinguishing between microbially and thermogenically formed natural gas components. Lines A and B show examples of natural gases with different compositions. Potential changes in the isotope values during storage and withdrawal provide important information on the functionality and quality of the storage formation.

Assessment of natural gas storage facilities

The isotopic chemical composition of methane, ethane and propane allows conclusions to be drawn about the genesis and origin of natural gas. Isotope studies on natural gas storage facilities thus provide insights into the spreading and mixing of the storage gas with the intrinsic natural gas that is already present. Furthermore, the tightness of the storage formation can be checked. The essential principles of data interpretation are based on

the correlation of the carbon isotope value of methane (d¹³C_CH4) and the concentration ratio of methane to ethane and propane (C₁ / ( C₂+C₃)) in a so-called Bernard diagram
the correlation of the carbon and hydrogen isotope values of methane (d¹³C_CH4, d²H_CH4 )

Based on the corresponding isotope analyzes and diagrams, we create well-founded reports on the functionality of natural gas storage facilities.

Schematic distribution of oil, natural gas and biogenic methane in a reservoir. In practice, thermal cracking processes, mixing and transport as well as biological methanogenesis lead to a more complex distribution of the fractions.

Isotope analysis for the development of natural gas

The diagenesis of petroleum and natural gas involves complex geothermal processes (cracking), transport and mixing of gaseous and liquid components, and the potential biological formation of methane. To explore the maturity of resources, Isodetect determines the isotopes of gas samples from different depths and zones of a reservoir or storage facility.

Isotope analysis of natural gas

13C: methane, ethane, butane, propane, pentane
2H: methane, ethane, butane, propane, pentane
13C-CSIA and 2H-CSIA: higher alkanes, condensates

In contrast to online on-site determinations, gas samples can be analyzed in the laboratory much more reliably and precisely.

In order to evaluate the origin and degree of maturity of the gases, various concentration and isotope parameters are displayed against each other in diagrams. Only the summary interpretation of the diagrams provides valid information.

Diagrams for evaluating gas provenance and maturity

The isotope values of the lower alkanes have to be put into different contexts in order to obtain meaningful information about the deposits. For example, they are shown in the context of the concentration proportions of methane and higher alkanes (so-called bernard diagram). We usually show six diagrams of many variants in our reports.

Diagrams for evaluating isotope data from natural gas reservoirs

Bernard: Methane – concentration C1/(C2+C3) vs. isotopes 13C/12C
Schoell-Whiticar: Methane – Isotopes 2H/1H vs 13C/12C
Ellis: Isotopes 13C/12C ethane vs 13C/12C butane and propane
James: Isotopes 13C/12C methane vs 13C/12C ethane and isotopes 13C/12C ethane vs 13C/12C propane
Lorant: Ethane vs. Propane – Isotopic Value Difference 13C/12C vs Concentration Ratio
Natural Gas Plot: Low Alkanes – Isotopes 13C/12C vs C-Atoms

In contrast to online on-site determinations, gas samples can be analyzed in the laboratory much more reliably and precisely.

Isotope studies to evaluate natural gas storage facilities and deposits

Assessment of natural gas storage facilities

Isotope analysis for the development of natural gas

Diagrams for evaluating gas provenance and maturity

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