Estimation of Uncertainties in Determination of Natural Gas Thermodynamic Properties Based Upon In-situ Raman Analyses of Gas Mixtures

thermodynamic properties of natural gas. Two methods of Raman
signal analysis are discussed. The first method is an analytical
algorithm based on linear regression, which utilizes peak area. The
second is an Artificial Neural Network algorithm that can utilize
both peak area and its position. A detailed discussion of presented
approaches is shown on reference data obtained using specially
designed setup Raman with 105 m long fiber optic probe and a
high-pressure cell. The proposed analysis allowed the calculation of
composition for any arbitrarily chosen pressure. The feasibility of
this approach is shown by the determination of composition for a
gas flow in a separator installation on a gas production well. Results
are compared with gas chromatography which allows the
uncertainty determination of the method.