The Major Controlling Factors Analysis of Hydrocarbon Accumulation on the Gentle Slope Belt of the Southeastern Liaodong Bay Depression

Abstract

Oil and gas discovery in the Liaodong Bay Depression is mainly distributed in the steep slope, the uplift and the sag zone at current situation. The reservoir developed on southeastern gentle slope zone is the first discovery in this area, which has great significance to the study of the gentle slope zone hydrocarbon accumulation regularity. Based on the analysis of the hydrocarbon accumulation condition of the gentle slope zone, the major controlling factors and hydrocarbon accumulation pattern of the gentle slope zone are summarized. It shows that the gentle slope belt has the superior accumulation conditions, where develops Lithological-tectonics traps and lithological traps Controlled by fracture and provenance. The source rock circumstance is advantageous too, because the gentle slope zone is close to the hydrocarbon-rich Liaozhong sag. The mudstone in Dongying formation(Ed) and the first section of Shahejie formation (Es1) and the sandstone in the second member of Shahejie formation (Es2) are form into a good reservoir cap association. Hydrocarbon accumulation in the gentle slope belt is mainly controlled by 3 factors: the development of the reservoirs in the Es2 is controlled by the valley-slope break coupling; the migration of oil and gas is controlled by “Fault-unconformity-sandbody”(FUS) long-range efficient migration system; reservoir physical properties and oil and gas test capacity are controlled by sedimentary facies differences. There are two reservoir models: lithology - tectonics and lithology.