Patent ID: 6997037

Claim:
A method for determining the effective composition of a gas mixture which contains a plurality of hydrocarbon gases, comprising: selecting one or more effective hydrocarbons to represent the plurality of hydrocarbon gases in the gas mixture, the number of effective hydrocarbons being less than the number of hydrocarbon gases in the gas mixture whose composition is to be determined; measuring a number of characteristics of the gas mixture whose effective composition is to be determined, wherein the number of characteristics to be measured is one less than the total number of components to be determined and determining the effective composition of the mixture of gases from (a) the measurements of the characteristics of the gas mixture, (b) a predetermined parameter dependent upon the characteristic measured, and (c) knowing that the sum of the components of the gas mixture equals 100%, wherein said gas mixture includes carbon dioxide and nitrogen in addition to a plurality of hydrocarbon gases and wherein the gas characteristics that are measured are thermal conductivity at a first temperature, thermal conductivity at a second temperature and the speed of sound in the gas.