鄂尔多斯盆地侏罗系煤生、排油能力实验及其形成煤成油可能性探讨

由于现代煤成油理论的建立和世界范围内一批大中型煤成油田的相继发现,鄂尔多斯盆地侏罗系煤生油问题引起地质学者的关注.该文通过实验获得鄂尔多斯盆地侏罗系煤饱和吸附烃量为50～88kg/t煤,为研究煤吸附烃提供了一些定量信息.同时认为,只有煤生油能力达到或超过煤饱和吸附烃量时,煤才可能成为有效油源岩.通过热模拟实验获得鄂尔多斯盆地侏罗系煤生油能力,结合鄂尔多斯盆地侏罗系煤饱和吸附烃量,对鄂尔多斯盆地侏罗系煤生烃能力进行评价,认为,鄂尔多斯盆地侏罗系煤生烃能力有限,大多数煤生成烃类尚不能完全饱和煤中的孔隙.同时对鄂尔多斯盆地侏罗系煤有机质丰度、类型、成熟度进行综合评价,并与世界其它大中型煤成油田进行对比认为:鄂尔多斯盆地煤有机质丰度较低、类型较差、成熟度不高、生油能力有限;油源对比的结果也认为,鄂尔多斯盆地侏罗系原油与侏罗系煤系地层烃源岩无关,从另一侧面也说明,鄂尔多斯盆地侏罗系煤生烃能力有限,形成工业性油藏的可能性不大.

AN EXPERIMENT OF GENERATION AND EXPULSION OF OIL FROM THE JURASSIC COALS AND ITS IMPLICATION OF COAL GENERATED OIL IN THE ORDOS BASIN

It is a hot topic if the Jurassic coal can generate oil in the Ordos Basin.The adsorbed hydrocarbons amount in the Jurassic coal is 50-80 kg/t but the productivity of coal is only 6.02-70.7kg/t based on the experimental result.If produced oil is less than adsorbed oil in coal,the coal cannot be an effective source rock of oil.On the other hand,comparing to the coal of large and medium sized oilfields in the world,the Jurassic coal in the Ordos Basin is characterized by lower abundance,unfavorable type and lower maturity,which indicates uneffective source rocks.In terms of characteristics of biomarker,the Jurassic oil is not generated by coal in the Ordos Basin.Therefore,the Jurassic coal in the basin can not generate sufficient oil to form a commercial oilfield.