True exploration potential of marine oils in the Tarim Basin

Abundant oil and natural gas is embedded in Palaeozoic strata of the Tarim Basin in which reservoirs are buried at the depth about 5500～10000m,The phase states of hydrocarbon fluids in depth or the depth where mass liquid oil lost is a concerned theoretical question,and the question that marine facies in the Tarim Basin rich in gas or oil related to the future deliverability plan of Tarim oil field,We studied the thermal stability of oil in the Tarim Basin,especially researched the compensating effect of low geothermal gradient and quick deep burial process,considered that the depth where oil cracking began is at 9000～10000m or deeper,and the correspondent reservoir temperature is higher than 210℃,a mount of oil may exist above this depth,Though the research of key geosciences problem of hydrocarbon migration and accumulation,it demonstrated that hydrocarbon mainly accumulated in Late Hercynian stage in the platform area,and hydrocarbon generated from source rocks are primarily charged into steadily existed paleo-uplifts and the slope area;during Late Hercynian stage,those carbonate reservoirs were buried in the depth of 800～2500m and karst reservoirs developed,which is the base of blanket hydrocarbon accumulation and consequently implied that reservoirs located in the slope area buried in depth of 7000～9000m will be the important prospecting region of black oil and condensate oil.