鄂尔多斯盆地延长组下组合油气来源及成藏模式

Hydrocarbon origin and reservoir forming model of the Lower Yanchang Formation, Ordos Basin

通过生物标志化合物对比、流体包裹体分析及盆地模拟研究,对鄂尔多斯盆地延长组长9与长10油层组的油源、成藏期次及成藏模式进行了探讨。陇东与姬塬地区长9油层组的原油分为2种类型,第Ⅰ类来源于长7烃源岩,第Ⅱ类来源于长9烃源岩;陕北地区长10油层组的原油主要来源于长9烃源岩。陇东与姬塬地区长9油藏均发生过2期油气充注,但前者在第1期(中侏罗统直罗组沉积期)就达到了油气充注的高峰期,而后者在第2期(下白垩统志丹组沉积期)才达到油气充注高峰期;陕北长10油层组也存在2期成藏,但2期油气呈连续充注,大致从中侏罗统直罗组沉积早期一直持续到下白垩统志丹组沉积中后期。长9与长10油藏有"上生下储"、"侧生旁储"及"自生自储"3种成藏模式。

According to the comparison of biomarkers in source rocks and crude oil,fluid inclusion analysis,and basin modeling,this paper discusses the oil source,hydrocarbon accumulation period and reservoir forming model of the Chang 9 and Chang 10 oil-bearing formations,Yanchang Formation,Ordos Basin.The crude oil of Chang 9 in the Longdong and Jiyuan areas can be divided into two types,type Ⅰc rude oil originated from the source rocks within Chang 7,while type Ⅱ crude oil came from the source rocks within Chang 9.The crude oil of Chang 10 in Northern Shaanxi originated mainly from the source rocks of Chang 9.The Chang 9 oil reservoirs in both the Longdong and Jiyuan areas experienced two periods of hydrocarbon injection.The former reached the peak period of hydrocarbon injection in the first period（the depositional period of Middle Jurassic Zhiluo Formation）,while the latter in the second period（the depositional period of Lower Cretaceous Zhidan Formation）.There are two periods of continuous hydrocarbon injection in Chang 10 of Northern Shaanxi,generally from the early depositional period of the Middle Jurassic Zhiluo Formation to the middle-late depositional period of the Cretaceous Zhidan Formation.There are three types of hydrocarbon accumulation models in Chang 9 and Chang 10,i.e.＂upper generation and lower storage＂,＂adjacent generation and lateral storage＂ and ＂self-generation and self-storage＂.