烃源岩生烃时效性对油气分布的控制作用——以松辽盆地南部东南隆起区梨树断陷为例

虽然很多盆地或断陷内油气藏的形成与分布往往受控于生烃中心，但是某些特殊地质背景的断陷或盆地就有例外，这是因为不同构造位置烃源岩生烃时效性的差异可以控制油气分布。通过对东南隆起区梨树断陷源岩演化史、油源对比的研究，认为深凹带源岩具有2期生烃作用，第一期生烃对现今油气藏没有贡献；第二期生成高成熟天然气为主，在深凹带的储层内成藏；而斜坡带源岩为一期生烃作用，生烃时期晚于深凹带源岩的第二期，以原油为主，主要聚集在斜坡带的储层内。因此不同构造位置的烃源岩生烃时效性不同，并且控制着油气的生成与运聚，进而控制着油气的分布。

CONTROL OF THE TIME EFFECT OF HYDROCARBON GENERATION ON DISTRIBUTION OF OIL AND GAS: TAKING LISHU FAULT DEPRESSION IN SOUTHEASTERN UPLIFTED AREA, THE SOUTHERN SONGLIAO BASIN, AS AN EXAMPLE

Although the formation and distribution of reservoirs in many basins or faulted depressions are generally controlled by hydrocarbon kitchen, there are some exceptional basins or fault depressions with specific geological settings, where the distribution of oil and gas is controlled by the difference in the time effects of source rocks at different structural locations. Study of the evolutionary history of source rocks and oil-source correlation in Lishu fault depression in the southeastern uplifted area shows that the source rocks in the deep sag generated hydrocarbons in two stages. The first stage of hydrocarbon generation has contributed nothing to the current oil & gas reservoirs, while the second stage was dominated by generation of highly mature gas, which accumulated in the reservoirs in the deep sag. The source rocks in the slope zone generated hydrocarbons in one stage later than the second stage of hydrocarbon generation from source rocks in the deep sag, and the generated hydrocarbons were dominated by crude oil, which mainly accumulated in the reservoirs in the slope zone. Therefore, the time effects of the source rocks in different structural locations are different, which controls the generation, migration and accumulation of oil and gas, and the distribution of oil and gas.