塔里木盆地和田河气田碳酸盐岩储层的多期次多来源油气聚集特征

高成熟度演化地区的海相碳酸盐岩储层易受到油气演化的影响 ,油气的聚集在储层中都留下了踪迹 ,既有对储层储集性能的改善有利的一面 ,也有对储层形成伤害的一面。对和田河气田的碳酸盐岩储层薄片观察、凝析油气的地球化学分析和储层沥青分析表明 ,主要有 3期油气运移 ,分别为 :晚加里东期—早海西期、晚海西期和喜山期。前两期都是寒武系来源的油气 ,均被生物降解或散失 ,喜山期是天然气的关键聚集时期。第一期以油相运聚的油气被降解 ,形成的沥青对储层造成了伤害 ,第二期以气相运移的油气多散失 ,仅在储层中留下凝析油 ,第三期油相运移的石炭系来源的油受到后期转移上来的寒武系干气的气侵 ,产生沥青质沉淀 ,使得寒武系凝析油被封堵 ,储层产出的凝析油的地球化学特征更接近石炭系源岩。

THE ACCUMULATION CHARACTERISTICS OF MULTIPHASE AND MULTISOURCE OIL AND GAS IN HIGHLY MATURED ORDOVICIAN CARBONATE RESERVOIRS IN HETIANHE GAS FIELD,TARIM BASIN,WEST CHINA

Carbonate reservoirs are easily subjected to the evolution of pooled oil variation which may improve the reservoir property or hurt it. Based on the microscopic observation of thin section and the geo\|chemical analyses of gas condensate and reservoir bitumen, three main phase of petroleum migrations have been recognized in the Ordovician carbonate reservoir in Hetianhe Gas Field. They are the secondary migrations occured in Late Caledonian to Early Hercynian epoch, Late Hercynian epoch and Himalayan epoch respectively. The former two migrations lead to the degradation and/or dissipation of Cambrian sourced petroleum while the last migrated dry gas is accumulated in the reservoir. Degradation of the oil pooled in carbonate reservoir causes solid bitumen filling and degrades its porosity, and dissipation of the secondly migrated petroleum leaves in the reservoir a little amount of gas condensate. In Himalayan epoch, the Carboniferous oil entered into the reservoir firstly, and then it was invaded by dry gas, which caused the asphaltene precipitation to seal the already existed Cambrian gas condensate as immobile residual oil. This is why the gas condensate produced in Hetianhe Gas Field displays some features more similar to the Carboniferous source rocks.