Abstract:

Analyses of geochemical characteristics and fluid inclusions of the Carboniferous oil pools in the Maigaiti area in Tarim Basin reveal that the natural gas here is dominated by marine sapropel-type gas with high-over maturity.In the Bashituo area,associated gas with high maturity is predominant,while in the Hetianhe gas field,a mixture of over-mature kerogen-cracking gas and crude-cracking gas occurs.Crude oil in the Bashituo area is dominated by highly-mature light oil with low content of sulfur and wax.Oil charging occurs at least in two stages and the preservation conditions are good.Oil-source correlation shows that the crude oil mainly originated from the Cambrian and has no genetic relations with the Carboniferous source rocks.In the Bashituo area,hydrocarbon pooling occurred mainly in two periods:one is the Late Hercynian when the oil and gas pools were destructed to some degree,and the other is the Himalayan when secondary condensate oil and gas were predominant.

Key words: carbon isotope, fluid inclusion, pooling period, geochemistry, Carboniferous oil and gas pool, Tarim Basin