塔里木盆地海相石油的真实勘探潜力

True exploration potential of marine oils in the Tarim Basin

塔里木盆地古生界蕴藏了丰富的海相油气资源,储集层目前埋深在5500～10000m。深部流体的相态或者说液相石油大量消失的深度下限是学术界比较关心的理论问题,而塔里木盆地海相到底富油还是富气也是关系到塔里木油田未来产能规划的现实问题。通过对塔里木盆地原油的热稳定性分析,特别是低地温梯度和晚期快速深埋过程的补偿效应研究,认为液态石油大量消亡(油裂解成气)的深度下限在9000～10000m以下,对应的储层温度大于210℃,在此深度之上液态石油可以大量存在。通过对油气聚集与保存的关键地质科学问题的研究,认为晚海西期是台盆区油藏的主要成藏期,烃源灶区生成的油气主要分布在稳定的古隆起及其围斜区域;而晚海西期这些古隆起及其围斜区碳酸盐岩储层埋藏深度在800～2500m范围内,岩溶储集体发育,这是台盆区形成大面积层状油气聚集的基础,也决定了现今埋深在7000～9000m深度范围内的斜坡区将成为黑油和凝析油的重要勘探接替区。

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.