Application of quantitative grain fluorescence techniques in analysis of hydrocarbon charge history in Dabei 1 gas reservoir, Kuqa Depression, Tarim Basin

For the study of charge history and distribution law of oil and gas in the Dabei 1 tight gas reservoir in the Kuqa Depression of the Tarim Basin,36 sandstone samples collected from wells DB 101,DB 103 and DB 2 were tested with quantitative grain fluorescence techniques.The results showed that wells DB 101 and DB 2 located in the same palaeo-trap while well DB 103 located in a separate palaeo-trap.Oils distributed in layers in those traps.The present water layers in well DB 101 were palaeo-hydrocarbon migration paths.Under the current gas-water interface in well DB 103,there might be residual oil layers,and the real gas-water interface was deeper.Part of the palaeo-oil reservoir in well DB 2 was destroyed in later stage.The distribution and evolution of palaeo-oil reservoirs played an important role in the present distribution of oil and gas accumulation.