SEDIMENTARY MICROFACIES OF QUANTOU FORMATION-QINGSHANKOU FORMATION OF SHALE OIL PARAMETRIC WELLS IN QIJIA-GULONG AREA

The development characteristics of sedimentary microfacies significantly affect the occurrence and exploitation of shale oil. Taking the cores from the upper part of 4th Member of Quantou Formation and lower part of 2nd-3rd members of Qingshankou Formation from SYY1 and SYY2 wells in Qijia-Gulong area of northern Songliao Basin as the research object, the paper studies the sedimentary microfacies through large-scale core observation and fine description based on core lithology, bedding structures, fossils, inclusions and electrical characteristics. It is concluded that lacustrine facies deposits are mainly developed in the cores of SYY1 and SYY2 wells, which can be divided into two sedimentary subfacies of shallow lake and semi-deep-deep lake, with five sedimentary microfacies including beach-bar sands in shallow lake, ostracoda beach, argillaceous shallow lake, semi-deep-deep lake mud and oil shale. The lower part of 1st Member of Qingshankou Formation is dominated by semi-deep-deep lake subfacies; while the upper part of 1st Member and lower part of 2nd-3rd members of Qingshankou Formation and upper part of 4th Member of Quantou Formation, by shallow lake subfacies. The latter three microfacies are all favorable to form shale oil.