Improvement of measurement accuracy using state equivalence correction for CH4 and CO2 sensor in geochemical application

Abstract

High-accuracy detection instrument is required to monitor temporal and spatial distribution of methane (CH4) and carbon dioxide (CO2) near fault zones. An environmentally adaptive CH4 and CO2 sensor is developed to achieve low power detection in the wild. A state equivalence correction (SEC) method based on state observer theory is proposed to monitor sensor state and improve measurement accuracy. SEC reduces the measurement error by one order of magnitude. SEC errors are less than 3.0‰ for both CH4 and CO2 in different environments. Geochemical application is conducted in Fengman Seismic Station to monitor CH4 and CO2. The measurement accuracies are better than 99.79% for CH4 and 99.77% for CO2. The measurement precisions are 99.83% for CH4 and 99.82% for CO2. Results validated the sensor presents potential in the monitoring of temporal and spatial distribution of CH4 and CO2.