A gas chromatographic method for analyzing natural gas, comprising: transporting the natural gas through a chiller; transporting the natural gas from the chiller to at least two gas upgrading membranes each comprising at least three upgraded product stream outlets (44, 46, 48, 54, 56, 58) placed to provide a first cut of upgraded natural gas, a second cut of upgraded natural gas, and a third cut of upgraded natural gas respectively; operating a gas chromatographic system comprising at least one upstream gas chromatograph and at least two downstream gas chromatographs (14, 16) comprising a first downstream gas chromatograph and a second downstream gas chromatograph, wherein the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph all operate simultaneously, the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph are all calibrated using the same calibration feed, and the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph all utilize the same heating oven to heat samples of natural gas; transporting samples of natural gas to the gas chromatographic system, wherein a sample of the natural gas exiting the chiller, a sample of the natural gas entering a first membrane of the at least two gas upgrading membranes, and a sample of the natural gas entering a second membrane of the at least two gas upgrading membranes are transported to the at least one upstream gas chromatograph, and a sample of the upgraded natural gas exiting each of the upgraded product stream outlets are transported to the at least two downstream gas chromatographs (14,16); and monitoring the composition of the sample of the natural gas exiting the chiller, the sample of the natural gas entering a first membrane of the at least two gas upgrading membranes, the sample of the natural gas entering a second membrane of the at least two gas upgrading membranes, and the samples of the upgraded natural gas exiting each of the product stream outlets (44, 46, 48, 54, 56, 58) with a controller to determine upgrading of the natural gas. transporting the natural gas through a chiller; transporting the natural gas from the chiller to at least two gas upgrading membranes each comprising at least three upgraded product stream outlets (44, 46, 48, 54, 56, 58) placed to provide a first cut of upgraded natural gas, a second cut of upgraded natural gas, and a third cut of upgraded natural gas respectively; operating a gas chromatographic system comprising at least one upstream gas chromatograph and at least two downstream gas chromatographs (14, 16) comprising a first downstream gas chromatograph and a second downstream gas chromatograph, wherein the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph all operate simultaneously, the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph are all calibrated using the same calibration feed, and the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph all utilize the same heating oven to heat samples of natural gas; the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph all operate simultaneously, the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph are all calibrated using the same calibration feed, and the at least one upstream gas chromatograph, the first downstream gas chromatograph, and the second downstream gas chromatograph all utilize the same heating oven to heat samples of natural gas; transporting samples of natural gas to the gas chromatographic system, wherein a sample of the natural gas exiting the chiller, a sample of the natural gas entering a first membrane of the at least two gas upgrading membranes, and a sample of the natural gas entering a second membrane of the at least two gas upgrading membranes are transported to the at least one upstream gas chromatograph, and a sample of the upgraded natural gas exiting each of the upgraded product stream outlets are transported to the at least two downstream gas chromatographs (14,16); and a sample of the natural gas exiting the chiller, a sample of the natural gas entering a first membrane of the at least two gas upgrading membranes, and a sample of the natural gas entering a second membrane of the at least two gas upgrading membranes are transported to the at least one upstream gas chromatograph, and a sample of the upgraded natural gas exiting each of the upgraded product stream outlets are transported to the at least two downstream gas chromatographs (14,16); and monitoring the composition of the sample of the natural gas exiting the chiller, the sample of the natural gas entering a first membrane of the at least two gas upgrading membranes, the sample of the natural gas entering a second membrane of the at least two gas upgrading membranes, and the samples of the upgraded natural gas exiting each of the product stream outlets (44, 46, 48, 54, 56, 58) with a controller to determine upgrading of the natural gas.