Application the FT-IR spectroscopy to study the accumulations of Permian mixed petroleum systems in the central Junggar Basin, NW China

Abstract

Oil-source and its differences in mixed petroleum systems are one of the most important scientific problems in petroleum geology and geochemistry fields. Geochemistry provides useful information for exploration including source rock quality, thermal maturity, oil-source correlation, migration and accumulation relative to trap formation, which greatly reduces the risk of petroleum exploration. Traditionally, petroleum geochemistry analysis relies heavily on gas chromatography-mass spectrometry and carbon isotopes, which have been used as proxies to connect the petroleum geochemistry with oil-gas exploration, and has achieved remarkable success. These methods, however, have met with difficulties more and more along the complexity of oil compositions in exploration. This is because oils are complex mixtures of aliphatics, aromatics and NSO (nitrogen, sulfur and oxygen) compounds. Thus, to develop new methodologies to study oil geochemistry becomes more and more urgent. In this study, we demonstrate that Fourier Transform Infrared (FT-IR) spectroscopy, as a new rapid and non-expensive alternative technique, could be used to investigate the mixed. Here we address this issue based on a case study in the Permian lacustrine petroleum systems within central Junggar Basin (NW China), of which results have been restrained by traditional molecular geochemistry. Results there are two main mixed-source areas with different mixing proportions in Sinan oil-field of the central Junggar Basin. This characteristic can be applied directly in regional exploration.