Fig. 1. Schamatic of the gas Raman spectroscopy system

Fig. 2. Raman spectra and calibration curves of CH₄， H₂ and CO₂ at different concentrations

Fig. 3. Experiment of Raman system detection limits and stability

Fig. 4. Drilling site and working picture of Raman system

Fig. 5. Raman spectra of logging gas

Fig. 6. Comparison of detection results of methane in gas logging with gas chromatography and Raman system

Fig. 7. Continuous measurement of hydrogen in logging gas