Five District Of The Junggar Basin Oilfield Accumulation Geochemical Study

This thesis takes the petroleum system theory and the oil reservoir geochemistry theory as the guide, inducts oil and gas "partition capture" and the biomarkers quantitation research thought, applies the entire hydrocarbon geochemistry method for the oil and gas reservoir geochemistry in South-of-fifth-area, establishes its petroleum migration and accumulation model, discovers the law which controls the pool, appreciates the exploration foreground of west slope in Mahu sag, points out the favorable exploration area.Through the hydrocarbon source rock appraisal, the geochemistry methods: the natural gas composition and the isotope analysis, the light hydrocarbon, biomarkers contrast analysis research, and so on, had determined the oil/gas type and its distribution rule in South-of-fifth-area the oil/gas field. The natural gas is too dry in research area, which is the overmature dry gas of Jiamuhe group and the postmature wet gas of Fengcheng group. The crude oil mainly comes from the source rock of Fengcheng group, some are the maturation crude oil, the other are high maturation condensate. The oil/gas pool formation time was determined by inclusive analysis and the oil/gas maturity analysis, combined the structure evolution history, the oil/gas migration and accumulation model was established. Three periods petroleum accumulation exists in South-of-fifth-area oil field, the first period oil and gas is the Jiamuhe group mature and high mature hydrocarbon and the Fengcheng group mature hydrocarbon in late Permian to early Triassic, was destroyed in the Indo-Chinese movement intermediate stage, but some still is conserved in good conserved condition, which is one of exploration objects. The second period is the Fengcheng group high mature hydrocarbon in late Triassic to early Jurassic, which is the important exploration target. The third period is the Jiamuhe group overmature dry gas in the late Jurassic Period to the early Cretaceous. The oil/gas is along the plane of unconformity the lateral migration, accumulation in lithological trap (fan body) or structure-lithological trap(fan body and fault or conformity formed) .According to migration and accumulation model, fined that the fan body controls the pool scale and the unconformity or the fault plays the hydrocarbon migration path role and shading function, therefore, fan body directly contacted with the source rock is the exploration goal to find the pool of generation and accumulation hydrocarbon by itself, or the fan body communicated source rock with unconformity or fault is the structure-lithological pool. Therefore, the exploration foreground is broad in west slope of Mahu sag.