吐哈盆地下侏罗统天然气勘探潜力与方向

Lower Jurassic Gas Exploration Potential and Target in Tuha Basin

通过气油比、地层温度对比等研究,认为柯19井下侏罗统(J1)气藏和丘东气田中侏罗统西山窑组(J2x)凝析气藏、小草湖地区中侏罗统西山窑组(J2x)三间房组(J2s)凝析气藏是相似的,是长期较高地层温度作用下油气裂解的产物。论证了柯柯亚下侏罗统八道湾组(J1b)气层属于后期致密型气藏,即早期油气成藏,形成期为晚侏罗-早白垩纪,油气在古油藏中继续演化为凝析气藏。一定气油比的烃体系、较高的地层温度、压力是形成凝析气藏的必要条件,吐哈盆地下侏罗统满足形成凝析气藏的条件。下侏罗统气藏主要受古构造控制,在丘东和小草湖地区有广阔的分布;在圈闭描述的基础上,指出近期勒东和红旗坎地区是下侏罗统天然气勘探的有利地区。

Through studying the gas -oil ration and the formation temperature correlation, it is believed that J1 gas reservoir of well Ke19, J2x condensate gas reservoir of Qiudong gas field, J2x -J2s condensate gas reservoir of Xiaocaohu area are similar, all of which are the results of oil - gas cracking under long - term high formation temperature. It＇s demonstrated that J1b gas strata in Kekeya is late - dense gas reservoir, that is reservoir accumulated at early stage but formed at Late Jurassic - Early Cretaceous. Hydrocarbon evolves into today＇ s gas condensate reservoir in the paleo - reservior. A hydrocarbon system with a certain gas - oil ratio, a higher formation temperature and pressure are necessary conditions for condensate gas reservoir. The lower Jurassic gas reservoir, widely distributed in Qiudong and Xiaocaohu areas, are dominated by paleostructure. At last, based on trap description, it is pointed out that Ledong and Hongqikan are the advantageous regions for gas exploration in Lower Jurassic.