| The beach-bar sandstone reservoir in upper Es4 formation of Dongying Depression contains enormous oil and gas resources and gradually becomes the new battlefield of exploration in the slope belt. Taking the two typical blocks Boxing Oilfield and Wangjiagang Oilfield as examples, guided by the theory of reservoir heterogeneity controlled hydrocarbon accumulation, the distribution of oil and gas in different horizons and areas were researched. Furthermore, the controlling factors of hydrocarbon heterogeneous distribution and hydrocarbon accumulation mechanism were discussed.The result shows that the hydrocarbon distribution and properties were extremely heterogeneous. Hydrocarbon in Boxing Oilfield is light with low viscosity and high freezing point. Along the hydrocarbon migration, the relative density and viscosity of crude oil are gradually increasing, oxidation action is obvious and chromatography effect is not significant. On the contrary, most of oil in Wangjiagang Oilfield belongs to heavy oil with high density and viscosity which is considered to have relationship to biodegradation, hydrolysis, etc.The hydrocarbon reservoir types in Boxing Oilfield are mainly fault-lithologic reservoir and physical sealing reservoir, however, in Wangjiagang Oilfield are fault block reservoir and fault nose reservoir. According to the occurrence of oil and water, five section-styles and planar patterns of oil deposits were classified.Basic migration pathways included interconnected pores, microbedding planes and layer interfaces. In the study area, three kinds of migration systems were recognized as lateral migration in basic pathway, migration in basic pathway and microcracks, step-shaped migration in basic pathway and faults. The sand body distribution, structure configuration and fault system controlled the regional migration direction and hydrocarbon accumulation location. The main control factors of hydrocarbon heterogeneous distribution were different under different tectonic background. Under similar oil source and tectonic setting, physical feature and heterogeneity of the reservoir are the most important factors for controlling hydrocarbon accumulation. Proposing to use the index of reservoir quality (IRQ) as evaluation index of reservoir quality, which is more than 0.4 in main oil area. The accumulation dynamics and resistance are important influence factors of hydrocarbon migration and accumulation. Two hydrocarbon accumulation models are established: reservoir heterogeneity controlled hydrocarbon accumulation model, and the fault-connecting sandbodies complex transportation system controlled hydrocarbon accumulation model.
|
PDF Full Text Request