Oil and gas reservoirs have been discovered in various strata within the Kekeya structural belt of the Tarim Basin, primarily consisting of pure gas reservoirs, condensate gas fields, and oil reservoirs. There are significant differences in the physicochemical properties of the oil and gas. 17α(H)-rearranged hopanes are commonly found in crude oil and may be key indicators for determining oil and gas migration pathways and correlating oil sources in the study area. Through chromatographic and mass spectrometric analyses of crude oil samples from five different strata in the Kekeya structural belt, the distribution patterns of 17α(H)-rearranged hopanes and 18α(H)-neohopanes were investigated. A comparative analysis of source rocks and crude oil confirmed that 17α(H)-rearranged hopanes originate from the Permian Pusige Formation source rocks. Further analysis of crude oil maturity and oil and gas migration revealed that low to moderate levels of 17α(H)-rearranged hopanes are influenced by maturity, whereas abnormally high levels are associated with oil and gas migration. Therefore, detecting the distribution characteristics of 17α(H)-rearranged hopanes in crude oil provides crucial evidence for determining the source and migration pathways of oil and gas in the Kekeya area.
Liu et al. (Mon,) studied this question.