利用生烃动力学研究鄂尔多斯盆地抬升后上古生界源岩生气作用结束时间

鄂尔多斯盆地上古生界气藏的研究已有较多的报道,但盆地抬升过程中源岩是否生气以及生气作用结束的时间等问题还存在争论或认识不清.本研究通过封闭体系的模拟实验,利用生烃动力学软件,对盆地不同区域代表钻孔的生烃史进行了计算.结果显示,在盆地的南部气体的转化率最高,可达70%以上,向北逐渐降低;在盆地抬升的过程中,源岩仍然有气体生成,不同地区的生气量随源岩的成熟度和降温幅度的不同而有所差别,总体来说盆地南部生气量低,西部高;生气作用在除天环坳陷外的广大地区,一般结束于老第三纪,并具有东早西晚的特点.天环坳陷到晚第三纪甚至现在仍有少量天然气生成.

The ending time of gas generation of the Upper Paleozoic source rocks in Ordos basin using hydrocarbon generation kinetics

There have been many reports about th e Upper Paleozoic gas pool in Ordos basin,but it is not clear or controversial whether source rock s till generated gas or not in the process of basin uplifting and when gas gen eration ended.In this paper,the gas generation history of representative well l ocated in the different area of the basin was calculated according to the results of simulation experiment and using h ydrocarbon generation kinetics software.The results show that the gas conversion ratio of source rock is the highest an d is more than 70%in the southern area of the basin,and it decreases from sout h to north.A lot of gases generated during uplifting of the basin,the amou nt of generated gas varies with the VRo of s ource rocks and the scope of temperature decreasing.Generally,the amou nt of generated gas in the western area i s greater than that in the southern on e in process of uplifting.The gas gen-eration ended in Early Tertiary in th e basin except the Tianhuan depression,the ending time of gas generation in the eastern area is earlier than that in t he western area.There is still littl e gas generation in Late Tertiary in t he Tianhuan depression.