Study On Oil-generating Potential Of Sikeshu Sag, Junggar Basin

In this thesis, by means of geochemical analysis and assessment, the oil-generating potential was systematically studied and the favorable places for prospecting were showed in Sikeshu Sag, Junggar Basin. The purpose of this is to establish the geochemical basis for the study of reservoir-forming conditions and the selection of exploration targets in the west part of the southern rim of Junggar Basin, and also to provide the theoretical support for exploration decision in Sinopec.'s west exploration area of Junggar Basin.The main research findings of this thesis are as follows: 1) In Sikeshu Sag, the middle-lower Jurassic source rocks are characterized by the major original organism input of terrestrial higher plants, the sedimentary environment of weak oxidation to weak disoxidation in fresh water, and the poorer organic types and preservation condition. By contrast, the source rocks of Anjihaihe formation in Palaeogene are characterized by lower hydrobios input, disoxidation in relatively salty water environment, and the favorable organic types and preservation condition. The muddy source rocks in this area commonly have lower organic matter abundance and lower thermal evolution degree leading to the weaker hydrocarbon-generating ability, whereas the middle-lower Jurassic carbargilite and coal generally reach to good to first-class rank in source rock evaluation. 2) Thermal simulating test showed that the source rock of Badaowan formation has stronger gas-generating ability versus weaker oil-generating ability, and the characteristics of sterane and terpane from thermal simulation products indicated that there are significant differences in geochemical feature between the source rocks of Jurassic lacustrine facies and coal measures. 3) The depth of hydrocarbon- generating threshold is 5000m for Jurassic source rocks and about 5300m for the source rocks of Anjihaihe formatin in Palaeogene. 4) The study of oil source made clear that Huoerguosi oil was from the source rocks of Anjihaihe formation in Palaeogene, Cretaceous oil from Ka 6 well was from the source rocks of Jurassic coal measure, Dushanzi oil and Palaeogene oil from Ka 6 well are the mixture from the two source rocks, and oils from Xi 5 well and...