MIGRATION CHARACTERISTICS OF OIL AND GAS OF THE LOWER CRETACEOUS, THE ERLIAN BASIN

Systemic research on oil and gas migration activities of main hydrocarbon generation sags in the Erlian basin is made based on experiment data from mud and sand. Migration characteristics of oil and gas is summarized as below: 1)Hydrocarbon discharge ratio of 2 sets of mature source rocks (K₁ba and K₁bt¹) in the Lower Cretaceous is about 32%-72%, thus estimated as the main hydrocarbon discharge stratum. The type Ⅰ hydrocarbon generation sag which has entered the peak stage is favorable for hydrocarbon (generation and discharge. 2)Based on mudstone) compression curve and clay mineral change, the rapid compression stage is the most favorable era for hydrocarbon discharge(primary migration). 3)Hydrocarbon generation zone of only the type Ⅰ sag is matched with mud rapid compression stage, forming good relation between hydrocarbon generation and migration. 4)Source fault and unconformity surface are the main channels for secondary migration, especially the K₁bt¹/K₁ba surface. 5)Hydrocarbon migration effect of the Wuliyasitai sag is the best, with that of the A'nan, Saihantala, Erennaoer sags worse. Crude oil in the Bayindulan and Jiergalangtu sags has not experienced long distance migration.