Research on flow units based on high resolution stratigraphic sequence

Key words:  flow units  stratigraphic sequence  Maling Oilfield  the 9th member of Yan 'an Formation

Abstract:

The braided river reservoir of the 9th member of Yan 'an Formation in Maling Oilfield had features of fast variation and strong heterogeneity. On the basis of core analysis, logging and production data, the spatial distribution of reservoir and barriers were determined in sequence stratigraphic framework. The reservoir was divided into E, G, M, P four types of flow units by preferred parameters. The controlling mechanism of flow units were analyzed in sequence stratigraphic framework, with the analysis result of well logging intersection, petrographic anatomy and depositional process. The results indicate that the petrophysics property and flowing ability are dominated by sorting, median grain size and matrix content, which contribute to the different sedimentary fabrics in different lithofacies of super-short cycles. The lithofacies association in different microfacies controls the flow unit variations in the vertical profile of short cycles. In the horizontal profile, the distribution of microfacies has an intern relationship with flow units. For instance, the bar and braided channel are advantageous microfacies relating with E and G flow units. Sand body stacked patterns and scales of similar microfacies are controlled by the sequence and facies association variation in middle-term cycles, which makes the interlayer differences in proportion of various flow units.