The Lower Cretaceous source rocks geochemical characteristics and thermal evolution history in the HaRi Sag, Yin-E Basin

摘要

The Lower Cretaceous lacks detailed comprehensive study of source rocks geo-chemistry characteristics and thermal evolution history as the target stratum of potential regional oil-gas exploration in the HaRi Sag, Yin-E Basin. Organic geo-chemistry methods were first applied to detailed study of organic matter content, type and maturity of Lower Cretaceous source rocks from the HaRi Sag. The results showed that the organic matter of K1Y formation Types I-II1 with high content and Immature-Early mature, K1S formation kerogen Types II1-II2 with relatively high content and Early-Mid Mature and K1B formation kerogen Types II2-III with low content and Late Mature-Main Gas Generation. The proposed maturity evolution history of source rocks in HaRi Sag based on EASYR(O) % model under the control of vitrinite reflectance (R-O%) shows the maximum geothermal gradient reached 48-52 degrees C/km and the maximum paleogeotemperature is over 190 degrees C at the end of Early Cretaceous, and the main timing of hydrocarbon generation is 106.3-80.0 Ma.