鄂尔多斯盆地西部地区侏罗系油藏储层评价及分类研究

Reservoir evaluation and its classification of Jurassic oil reservoir in western Ordos basin

为了深化鄂尔多斯盆地西缘逆冲带侏罗系陆相砂岩油藏富集规律研究及进行致密油藏"甜点"预测,利用鄂尔多斯盆地西部地区丰富的测井、铸体薄片、扫描电镜及物性测试资料,开展了侏罗系油藏储层评价及储层分类研究。结果表明,侏罗系油藏岩性主要包括岩屑石英砂岩、岩屑长石砂岩及长石岩屑砂岩。岩屑组分以变质岩岩屑为主,其次为岩浆岩岩屑和沉积岩岩屑。填隙物包括水云母、高岭石、硅质、铁白云石、硬石膏等。砂岩的孔隙类型主要为粒间孔,其次为溶蚀孔、晶间孔及少量微裂缝。目的层在纵向存在两个孔隙度高值区,其是溶蚀作用及古超压综合作用的结果。在岩石学、物性及成岩作用综合研究基础上,构建了侏罗系砂岩储层综合评价分类标准。侏罗系油藏有统一的油水界面,构造高部位的Ⅰ类及Ⅱ类储层区利于烃类的大规模聚集。该研究可以为鄂尔多斯盆地西缘侏罗系油气勘探提供储层方面的依据。

In order to deepen the research on the enrichment law of Jurassic continental sandstone reservoir in the thrust belt on the western edge of Ordos basin and predict the"dessert"of tight reservoirs,the reservoir evaluation and classification of Jurassic oil reservoirs are carried out by using logging,cast thin section,scanning electron microscope and physical property test data in the western part of Ordos basin.The results show the lithology of Jurassic reservoirs is mainly of lithic quartz sandstone,lithic feldspar sandstone and feldspar lithic sandstone.The cuttings are mainly of metamorphic rock cuttings,followed by magmatic rock cuttings and sedimentary rock cuttings.The interstitial materials include hydromica,kaolinite,siliceous,iron dolomite,and anhydrite.The pore types of sandstone are mainly intergranular pores,followed by dissolved pores,inter-crystalline pores and a few micro-cracks.There are two high-value regions of porosity in the target layer in the longitudinal direction,which are the result of the combined effect of dissolution and paleo-overpressure.Based on comprehensive research on petrology,physical properties and diagenesis,a comprehensive evaluation and classification standard for Jurassic sandstone reservoirs was constructed.Jurassic reservoirs have a uniform oil-water interface,and the TypeⅠand TypeⅡreservoir areas in the structural high positions are conducive to the large-scale accumulation of hydrocarbons.This study can provide scientific guidance for Jurassic oil and gas exploration in the western margin of the Ordos basin.