Abstract:

Paleogene in Chaluhe depression, Yitong basin is graben-like fault basin sedimentary, and the reservoir is lacustrine subaqueous fan of gravity flow origin  and characterized by proximal provenance, fast accumulation rate, various lithology of sandstones. Under the influence of later diagenesis, the sandstones have variable parameters in physical property, and are at a high level of heterogeneity. In order to evaluate this hydrocarbon reservoir via conventional log data, and promote the success of log interpretation, we establish a suit of interpretation model for the lithology, physical property and hydrocarbon-bearing characteristics in this region, by the method of comprehensive analysis of reservoir rock types, physical character and hydrocarbon-bearing nature, integrating with the test result of production well. The cross plots of different log interpretation parameters can remarkably distinguish gas lay, oil lay, gas and water lay, oil and water layer, water layer, and dry layer with different hydrocarbon characteristics. The cross plots indicate that oil and gas reservoirs have the limited oil saturation lower than 20% by volume, and gas-productive layers have much higher resistivity dispersion of deep-shallow dual laterolog. The pure water layers have oil saturation less than 20% by volume, although with high quality physical property. The dry layers have more than 22% muddy content by volume, causing the total porosity less than 10.5% by volume, and become the ineffective reservoirs because of the bad physical property.

Key words: graben-like fault basin, lacustrine subaqueous fan, comprehensive liquid identification of hydrocarbon reservoir, Yitong basin, Chaluhe depression, petroleum gas