Geochemical Studies Of Marine Crude Oil Of The Halahatang Depression

The Halahatang depression is located in good foreground of gas and oil, this area has become the important district for oil exploration, Geochemical studies on petroleum migration and accumulation of the Halahatang depression is significant to the forming theory of marine crude oil exploration in Tarim cratonic basin. Applying qualitative and quantitative analysis (such as GC, GC/MS), similarity of crude oils are described according to the detailed analysis on crude oil chemical composition, the difference from crude oils of Halahatang depression in the physical properties of crude oil, the distribution of normal alkane, the concentration of sterane and terpane, relative concentration of different structural steroid and maturity parameters of oil etc. Tarim basin sinks had developed two source rocks:middle & upper Ordovician source rocks and Cambro & Lower ordovician source rocks,the former mainly developed phase and evaporation in owe compensation basin, the lagoon deposition mainly distributed in the basin area half a block-block land-sourced gulf and high platform margin slope plaster organic phase, therefore, middle & upper Ordovician source rocks and Cambro & Lower ordovician source rocks has different combination characteristic. According to former face hara ha pond sag oil samples of tarim area the analysis and summary of the hydrocarbon source rocks distribution, using oil aliphaltic gas chromatography curve,25-Norhopane, CPI and Pr/Ph OEP,terpene silane maturity parameters Ts/(Ts+Tm) and C29Ts/(C29Ts+C29 Hopanoid), C29αββ/(ααα+αββ) and Ts/(Ts+Tm), crude oil dibenzothiophene parameters MDBT/1-4-MDBT and Ts/(Ts+Tm), rules C35H/C34H cyclodienylsilane. steroids, Pr/nC)17 and Ph/nC18, gammacerane, the contrast of hydrocarbon source rock in the various chemical characteristics, we can deduce the Halahatang depression sag reservoir at least through two phases of hydrocarbon hydrocarbon-charging, after the first oil and gas injection, there is a strong crude oil, namely the biodegradation of early destruction may for the residual compounds and crude oil mixtures of late, then came heavy oil,25-Norhopane the massive existence of silane herb confirmed that, while oil also contains a complete normal alkanes and isomerization alkane hydrocarbon,when the second because it happened hydrocarbon-charging. Correlation of age-specific biomarkers suggested oils in Halahatang depression originated from middle & upper Ordovician source rocks.