Study On Hydrocarbon Source And Hydrocarbon Accumulation Of Key Structure In The North Ring Zone Of Haizi Sag, Donggang, Junggar Basin

The margin of Dongdaohaizi sag is one of the hotspots in Dzungaria basin. There is a phenomenon of widespread hydrocarbon display in Dinan salient not only on plane but also on formation, but a few of larger scale reservoir formations were discovered. Therefore, the source rocks evaluation of Dongdaohaizi sag, oil-source correlation, and the establishment of reservoir models is the most important three missons of area exploration.The source rocks of Dongdaohaizi sag is buried very deep which few well reached, based on the drilling datas in the margin of sag and correlation with Wucaiwan sag, there are three suits of source rocks recognized in Dongdaohaizi sag:humic type Conboniferous source rock, sapropel type Perminan source rock and humic type Jurassic source rock. The Perminan Pingdiquan formation sorce rock with the organic material of high abundance, good tape and mature degree has an excellent ability of oil supply. Study of the evolutionary history of source rocks with the support of geophysical datas, Basin burial history and regional geothermal gradient, indicates that, the Perminan Pingdiquan formation source rock is in the high mature stage, but the source rock under Dinan1well is in prematurely stage. Oil-source correlation under the direction of All Hydrocarbon Geochemistry Theory reveals that:The majority of the oil is from Perminan source rock in mature stage, except for Dinan8well, which in the high mature stage, and some wells composited with oil from Conboniferous source rock; The majority gas of the oil in this area is from Conboniferous source rock, some wells composited with gas from Perrminan source rock, individual wells are constructed by pure Perminan source rock gas. Reservoir formation studying indicates that:reservoir formations in the west and south of the middle of Dinan salient are the products of twice period filling, the antephase oil suffered severe biodegration, oil in present tectonic migrated from paleo tectonic; Reservoirs in east of the Dinan salient formed quite late, which are the products of constant filling from slope area source rock. There are two potential reservoir models about Dinan8well:oil and gas from Perminan source rock filled reservoir in the first, and gas from Conboniferous source rock composited follow-up is the first model; another model hold the view that Conboninferous-gas have an effect of driveling oil, which pushed the oil to the formation. The studying of Dinan8reveals the occurrence of high mature oil from Perminan source rock in the slope area, and conserved properly, which is one of the emphases of exploration. Phenomenon of oil migrated from paleo tectonic indicates that finding paleo tectonic filled with oil is an exploratory emphase as well.