Research on Seepage Barriers of Massive and Superimposed Thick Oil Layers in the Low Oil Formation of No. 9 Block in Tahe Oilfield

The low oil formation reservoir of No. 9 block in the Tahe Oilfield is a superimposedmassive braided river delta reservoir, moreover, distribution and connectivity of the interlayers as well as complexity produced the sealing faults, argillaceous barriers, calcareous cemented zones and other different–level seepage barriers to control the movement of oil and water within the reservoir is to deepen the heterogeneity of the reservoir space; and the analytic hierarchy process is adopted based on the analysis of the reservoir configuration, and combined with dynamic and static, to clarify the seepage barrier types and levels;the formation mechanism of calcareous cement zone and its controlling factors is analyzed by researcher, so that establishes a geological model for the distribution of seepage barriers in massive thick oil layers; Researches show that the main seepage barriers of the low oil formation in No. 9 Block of Tahe Oilfield are sealing faults barriers, mud barriers, and calcium cemented zones, what is more, it can be divided into four levels according to the seepage blocking effect, and northeast sealing faults and the 6–level interface at the top of the composite channel are the first–level seepage barrier, the 3～5 level configuration interface controls the 2～4 level mud and calcareous seepage barriers; to establish three types of seepage barrier modes composed by completely uncover, partial cover, and completely cover. The spatial distribution of seepage barriers is characterized by hierarchical and sub–quantitative methods, which deepening the study of reservoir spatial heterogeneity, and laying the foundation for fine geological modeling based on flow units.