临南洼陷沙三中基山砂岩储层特征及有利目标预测

Reservoir characteristics and favorable target prediction of the Jishan sandstone in the middle segment of the third member of the Shahejie Formation,Linnan Subsag

渤海湾盆地临南洼陷古近系沙河街组三段中亚段(沙三中)基山砂岩石油资源潜力较大,但目前该区储层展布规律不清,严重制约着油藏的后续开发。利用钻井、测井、地震等基础资料,以地震沉积学、储层地质学理论为指导,剖析了沙三中基山砂岩的储层成因类型,明确了有利储层特征,预测了有利储层分布。研究表明,临南洼陷沙三中基山砂岩为三角洲-浊积扇沉积体系,微相类型以水下分流河道、河口坝为主,边部发育席状砂,洼陷带发育浊积岩;储层岩石类型为块状岩屑细砂岩、岩屑粉砂岩及含砾砂岩,分选磨圆较差,平均孔喉半径约0.5μm,河口坝、水下分流河道成因的砂岩厚度大、物性好,为有利储层类型;应用均方根振幅、有效频宽、相位谱3类地震属性RGB融合储层反演,与实钻情况对应性好,可以较准确预测有利储层分布,对该区油藏进一步勘探开发具有重要的指导意义。

The Jishan sandstone in the middle segment of the third member of the Shahejie Formation of Paleogene in the Linnan Subsag of Bohai Bay Basin has a large potential for oil resources,but at present,the law of reservoir distribution in this area is unclear,which seriously restricts the subsequent development of the reservoir.Based on the basic data of drilling,logging,and seismic,and guided by the theory of seismic sedimentology and reservoir geology,the reservoir genetic types of the Jishan sandstone in the middle segment of the third member of the Shahejie Formation are analyzed,the favorable reservoir characteristics are defined,and their distribution is predicted.The study shows that the Jishan sandstone in the middle segment of the third member of the Shahejie Formation in the Linnan Subsag is a delta-turbidite fan sedimentary system,with microfacies types dominated by underwater distributary channels and estuarine dams,the development of sheet sand at the edge,and turbidite in the sag zone.The reservoir rock types are massive lithic fine sandstone,lithic siltstone,and pebbly sandstone,poorly sorted and rounded,with an average pore-throat radius of about 0.5μm.The sandstones for estuarine bar and underwater distributary channel genesis have large thicknesses and good physical properties,which are favorable reservoir types.The application of RGB fusion reservoir inversion with three types of seismic attributes,namely,root-mean square(RMS)amplitude,effective bandwidth,and phase spectrum corresponds well with the actual drilling situation,and can accurately predict the favorable reservoir distribution,which has important significance in guiding further exploration and development of the reservoirs in this area.