关键词: 盐下层系, 碳酸盐岩油气田, 油气地质, 有利区带, 滨里海盆地

Abstract:

The series of strata below the halite have favourable petroleum geological conditions in southern Pre-Caspian basin.The extensively developed mudstones and marls have large hydrocarbon generating potentials,the high quality carbonate reservoirs,especially the bioherms,are widely distributed,and the thick halite cap-rocks in Kungurian Fm are well developed in the whole basin except some local areas on the basin margin.Therefore,the source-reservoir-cap rock combination is very good in this basin.The distribution of oil(gas)pools and fields are controlled by the development and distribution of traps and high quality carbonate reservoirs of shallow water platform facies(such as Astrakhan condensate gas field)and biohermal facies(such as Tengiz and Kashagan oil fields)that developed on the long-term stable palaeohighs and palaeoslopes below the thick halite layers.The western South-Enba depression(the northern part of Caspian sea)is the most favourable area for exploration of oil and gas pools below the halite in southern Pre-Caspian basin,followed by the eastern South-Enba depression,the northern Caspian uplift zone and Biikzhal uplift zone,while the Astrakhan quaquaversal dome with well developed deep carbonates,the southern Astrakhan structural zone and the South-Enba uplift are relatively favourable exploration areas.

Key words: southern Pre-Caspian basin, series of strata below halite, carbonate oil and gas fields, petroleum geology, favourable(areas)