鄂尔多斯盆地南部侏罗系油砂的发现与成藏模式

Discovery of Jurassic oil sand in southern Ordos Basin and its accumulation model

本次工作新发现的油砂矿藏位于陕西省铜川市庙湾地区。地层特征和孢粉组合分析表明含油砂地层为侏罗系。野外调查和钻探工作证实渭北隆起的北部单斜构造地表出露大量的侏罗系延安组和直罗组油砂,累计厚度可达29.85 m;钻井油砂累计厚度达11.89 m,最大单层厚度达7.9 m,埋深在70m以浅。油砂主要赋存于中下侏罗统延安组和直罗组河流相辫状河道沉积砂岩孔隙和裂隙之中。该油砂矿藏是在渭北隆起演化的基础上,经燕山晚期构造运动抬升形成,属于抬升运移型成藏模式。经初步资源量估算,研究区油砂油地质资源量为3 232.72万t。

The newly discovered oil sand deposit is located in Miaowan area,Tongchuan city,Shaanxi Province.Stratigraphic study and sporopollen assemblage show that the oil sand is of Jurassic.Field investigation and drilling confirm that oil sands of Jurassic Yanan and Zhiluo formations exposed on the northern monoclinal structure of Weibei uplift are 29.85 m thick in total.Drilling data confirm accumulated net oil sand of 11.89 m,with maximum thickness of 7.9 m for single layer.The maximum burial depth for oil sand is 70 m.The sand bodies occurred in braided river channel are favorable reservoirs,and secondary pores and cracks are developed in reservoir sand-stone.The oil sand was formed on the basis of Weibei uplift evolution,followed by tectonic deformations in the Yanshanian stages.Oil accumulation model can be summarized as uplifting related migration and accumulation.The preliminary oil sand resources is estimated as 3 232.72 × 10^4 t.