塔里木盆地深层海相轻质油/凝析油的成因机制与控制因素

塔里木盆地是中国蕴含丰富海相凝析油的克拉通含油气盆地,目前已在塔北隆起、塔中隆起及其斜坡区的震旦系—三叠系发现6个大型海相凝析油气藏,这些油气藏呈现出轻质油、高含蜡凝析油气、干气—轻质油—挥发性油多种类型油气藏围绕烃源岩有序聚集的特点.基于烷烃损失量计算、凝析油中烃类分子成熟度参数和天然气同位素组成的分析,提出塔北隆起...

Genetic mechanism and controlling factors of deep marine light oil and condensate oil in Tarim Basin

Tarim Basin is an oil-gas bearing craton basin rich in marine condensate oil in China. At present, six sets of large marine condensate reservoirs have been found in Sinian-Triassic formations in north Tarim uplift, middle Tarim uplift and their slope areas. These reservoirs are characterized by orderly accumulation of light oil, high-wax condensate, and dry gas, light oil and volatile oil reservoirs around source rocks. Based on calculation of alkane loss and analysis of the hydrocarbon molecular maturity in condensate oil and the gas isotopic composition, it is proposed that the light oil in the Manshen-Shunbei area of Tabei uplift and the condensate reservoir in the west of Tazhong uplift are the products of source rocks in the high-maturity evolution stage, it is further clarified that gas-washing fractionation is the main genetic mechanism of marine condensate reservoirs in Lungudong-Jilake-Sangtamu area and eastern Tazhong area. The multi-stage hydrocarbon charging caused by differential hydrocarbon generation from multiple sets of source rocks provides the material basis for the accumulation of marine condensate oil reservoirs in Tarim Basin. The alteration of early reservoir by late natural gas results in solution and dissolution of liquid hydrocarbon components and natural gas. The changes of formation temperature and pressure caused by tectonic uplift or fault activity dominate the phase state of oil and gas reservoirs. The multi-stage tectonic activities of superimposed basin, multi-stage hydrocarbon charging from multi-source kitchen and the continuous deep burial of the basin in the late stage jointly control the enrichment and distribution of marine light oil and condensate reservoirs in Tarim Basin. The mechanism of gas-washing fractionation can not only provide a new idea for expanding the field of light oil and condensate oil exploration in the superimposed basin, but also help to predict the physical properties of oil and gas in the deep slope area of the basin and evaluate the exploration potential of deep natural gas.