关键词: 生物标志化合物, 碳同位素, 油气源对比, 东坪地区, 柴达木盆地

Abstract:

In recently years, several giant natural gas fields have been found in East Africa, which makes Mozambique and Tanzania in East Africa become the focus of the gas generation in the whole world. According to new foreign statistical data, it is believed that the gas in East Africa are all from a same basin-Rovuma Basin. Rovuma Basin is one of the few unexplored Tertiary delta sedimentary basins in the world. Recent natural gas exploration findings confirm that the basin has huge resource potential and favorable exploration prospect, but the exploration degree is low, and the knowledge of natural gas generation and accumulation is still at the primary stage. It is supposed that there are four set of source rocks, the gas is mainly of thermogenic gas in Mesozoic strata, and Paleogene biogenic gas may also exist. The main reservoirs are delta sand bodies in Paleocene, Eocene and Oligocene of Paleogene and Miocene of Neogene. The potential reservoirs include Permian-Triassic clastic rocks, Upper-Middle Jurassic clastic rocks and carbonate rocks and Cretaceous clastic rocks and carbonate rocks. In the background of global transgression, Upper Cretaceous shale is regional cap rock, Paleogene and Neogene layer shale is local cap rock, and during Jurassic and Cretaceous, shale can act as potential cap rock in the sedimentary environment of restricted sea. Rovuma Basin is a composite basin of lower rift deposit and upper delta sediment, which has excellent hydrocarbon accumulation condition. The study of Rovuma Basin will be in favor of guiding the international corporation in east Africa, and help the decision of oversea energy strategic target.

Key words: biomarkers, carbon isotope, oil-gas source correlation, Dongping area, Qaidam Basin