THE GEOCHEMICAL CHARACTERISTIC AND GENETIC TYPE OF CRUDE OIL IN THE WESTERN SAG OF THE LIAOHE BASIN

The physical property and group composition of the crude oil in the Western Sag,Liaohe Basin possess the characteristics,such as density,consistency and wax content increase,while saturated hydrocarbon content decrease and nonhydrocarbon and asphaltene content increase along with the oil from deep to shallow layer,from center to boundary of the sag.Saturated hydrocarbon has various spectrums,such as single peak and double peak,front and queen,smoothing and serration,as well as biodegradation.The rate of Pr/Ph in the south is higher than the north.The distribution of C₂₇-C₂₉ regular sterane is dominated by right line ramp type,and only few samples have higher C₂₈ content in the south.Summing up the physical property and geochemical behavior,the crude oil are divided into two types based on biologic source and sedimentary environment,then divide these two types into three subtypes based on maturity and biodegradation.The results will provide dependable foundation to correlation of oil-source rock and exploration.