Measurement Uncertainty and Risk of False Compliance Assessment Applied to Carbon Isotopic Analyses in Natural Gas Exploratory Evaluation

• DOI: 10.3390/molecules29133065
• Publication Date: 2024-06-27T12:57:50Z
• Authors: Fabiano Leal; Alexandre de Andr...; Gabriel Silva; Tulio Freire; Marcelo Costa; Erica de Morais; Jarbas Guzzo; Elcio de Oliveira
• Keywords: Propane; Carbon fibers

The concept of uncertainty in an isotopic analysis is not uniform the scientific community worldwide and can compromise risk false compliance assessment applied to carbon analyses natural gas exploratory evaluation. In this work, we demonstrated a way calculate one main sources uncertainty, which underestimated most studies focusing on analysis: δ13C calculation itself primarily based raw analytical data. composition methane, ethane, propane, CO2 was measured. After detailed mathematical treatment, corresponding expanded uncertainties for each analyte were calculated. Next, systematic characterization two standards, calculated standard intermediary precision, combined finally, CO2. We have found value 1.8‰ all compounds, except where 1.6‰ obtained. values with approach shown study reveal that error arising from application delta algorithms cannot be neglected, obtained are higher than 0.5‰, usually considered as accepted associated GC-IRMS analyses. Finally, use information evaluate compliance, lower upper acceptance limits methane calculated, considering between −55‰ −50‰: (i) current limits, respectively, −54.6‰ −50.4‰; (ii) proposed realistic 1.8‰, would more restrictive; i.e., −53.5‰ −51.5‰, respectively.