Abstract:

Changling sag locates in Songliao Basin’s south of the central depression area, Suotu Region is located in south central Changling sag. Based on the drill core records, well logging data, seismic profiles, rock thin sections, data of physical property, and Hg-injection test data, this study focuses on the reservoir heterogeneity of Qingshankou Formation. The results are summarized as follows. The majority of spaces in the reservoirs of Qingshankou Formation in  Suotu region are undeveloped interparticle spaces, intraparticle dissolved pores and unmatured pellet internal pores. The main oil-bearing members in well 301 area are dominated by medium-low porosity and ultra-low permeability reservoir. The lamination factor and sandstone percentage by columnar section in the area imply a strong macroscopic heterogeneity, with a type of “mudstone-wrapping sandstone”and a weak connectivity of sandstone. The normal rhythm and composite rhythm lead to granularity heterogeneity in the single sandstone layer, and structures result in the heterogeneity of permeability, thus providing a strong permeability heterogeneity in the layers. The divergence of grain sizes in different directions results in the heterogeneity of permeability in the area. However, a weak heterogeneity is relatively shown in the horizontal direction. The microscopic heterogeneity in the area is characterized by  generally small size spaces, weak reservoir spaces connectivity, good sorting, medium concentration of main infiltration passageway, and weak heterogeneity.

Key words: reservoir, heterogeneity, Qingshankou Formation, Suotu area