鄂尔多斯盆地南梁地区长4+5油层组储层特征

Reservoir characteristics of Chang 4+5 oil reservoir set in Nanliang area,Ordos Basin

鄂尔多斯盆地南梁地区延长组长4+5油层组是该区重要的储集层之一,包括长4+51和长4+52共2个小层。通过储层岩石学、储层物性、孔隙结构及储层控制因素对该区储层特征进行了分析,并评价了储层的储集性能。结果表明:该区砂岩以长石砂岩和少量岩屑质长石砂岩组成;储层孔隙类型以粒间孔和溶蚀孔为主;喉道以细—微细喉道为主,排驱压力相对较高,属超低渗储集岩。沉积作用和成岩作用是造成储层超低渗的主要原因。沉积作用控制了砂体的展布;成岩过程中压实与胶结作用使储层孔隙大量减少,而黏土膜胶结、溶蚀作用和烃类侵位对孔隙建造具有积极作用。根据岩性和物性特征,将该区储集岩划分为2类,优质储层的勘探应以沉积作用控制下的多套砂体相互叠置的水下分流河道沉积为重点。

The Chang 4+5 oil reservoir set which is composed of Chang 4+52 and Chang 4+51 sublayers in Nanliang area in Ordos Basin is an important oil reservoir.Based on petrological and physical features,this paper studied the characteristics of Chang 4+5 oil reservoir set and evaluated reservoir properties.The result shows that the reservoir sandstone is compose of arkose and lithic arkose;the pore types are mainly intergranular pores and dissolved pores;the main throat type is fine to micro-fine throat and the reservoir displays high displacement pressure.It indicates that Chang 4+5 oil reservoir set belongs to ultra-low permeability reservoir.Sedimentation and diagenesis are the main factors of ultra-low permeability.Sedimentation controlled the distribution of reservoir.Compaction and cementation decreased the primary pores,while chlorite-cementation,dissolution and hydrocarbon emplacement play constructive role of the porosity building.Based on lithology and physical properties,the reservoir rocks can be divided into two types.The favorable reservoir should be in the subsea distributary channel sand bodies controlled by sedimentation.