摘要
Paleo-oil reservoir is of great importance to understand hydrocarbon enrichment mechanism and hydrocarbon exploration potential,but is yet poorly investigated in Kuqa Depression.The occurrence of the paleo-oil reservoir in Dabei area was proved by quantitative grain fluorescence(QGF)and fluid inclusion petrography.Development history of the paleo-oil reservoir was reconstructed through:(1)oil-source correlation;(2)time coupling of source rock maturation,porosity evolution and migration pathways.The impact of paleo-oil reservoir on tight-gas accumulation was consequently discussed.Results suggest that considerable oil was accumulated in the K_(1)bs reservoir with paleo oil-water contact in Dabei 2 Well and Dabei 201 Well at 5800 and 6040 m,respectively.Crude oil was primarily sourced from Triassic source rocks with Jurassic source rocks of secondary importance,which was at oil generation window(0.7%–1.1%Ro)during 9–6 and 7.5–5 Ma,respectively.The occurrence of K_(1)bs tight reservoir(porosity<12%)was about 25 Ma,while faults and associated fractures at Kelasue structural belt were developed approximately from 8 to 3.5 Ma.Therefore,the tight oil accumulation was formed during 8–5 Ma.The paleo-oil reservoir in Dabei 1 gas field was destroyed by the evaporation fractionation in later stage.
基金
supported by the China National Science and Technology Major Project(No.2016ZX05047-001-006).
