FN5井区夏子街组异常高阻段成因及油气成藏主控因素

Master control factor of reservoir-formation in abnormally-high-resistivity reservoir,P2x,FN5 region

通过岩心、薄片、构造演化史、古地貌等对FN5井区二叠系夏子街组异常高阻段进行综合分析.结果表明:FN5井区二叠系夏子街组异常高阻段发育2种岩性,高阻致密隔层以粗粒级云化凝灰质砂砾岩为主;低阻储层段以细粒级凝灰质细(中细)砂岩为主,储集空间具裂缝—孔隙双重介质特征.垂向上主要分布在夏子街组中部的P2x22砂层组;平面上主要分布在扇三角洲前缘近岸坡折带以下FC1—F20—FN055—FN5—W27井一带,面积为6.2km2,平面形态呈孤立的土豆状.油藏类型为东南方向受乌南断裂控制、其余方向受岩性控制的构造—岩性油藏.其展布受扇三角洲前缘的近岸水下坡折控制,后期成藏受控于异常高阻段的厚度及距主控断裂乌南断裂的距离.具有油层垂向厚度大、单井产量高、储量丰度高特征.为乌尔禾地区二叠系2011年探明储量培植及2012年增储上产的主要层位.

Through the analysis of cores and slices,the lithology of P2x stratum in FN5 region could be divided into three types.Normal elastic rocks are characterized by mudstone,interbedding of sandstone and glutenite,while the abnormally high resistivity reservoirs(AHRR) are characterized by dolomitization tuffaceous glutenite in compact layer,and tuffaceous packsand&fine-median grained sandstone in reservoir.AHRR above mentioned belongs to underwater distributary channel in fan delta front,The hydrocarbon pore volume is characterized by crack-pore,the pore types are divided into interparticle dissolution pore,granular solution pore and surplus grain of the hole,and belong to middle-low porosity,low permeability reservoir overall.The spread of AHRR is controlled by underwater rupture in Fan delta front,while its pool forming is controlled by WN fault.AHRR is mainly located in P2x22 in the vertical direction,and regions near FC1-F20-FN055-FN5-W27,its area is 6.2 km2.AHRR is characterized by bigger thickness,higher individual well producing rate and higher reserve abundance.And now,AHRR in FN5 region is developed into the main horizon which will contribute to proved reserves cultivation in 2011 and increase in oil reserve and production in 2012,Xibeiyuan,Junggar Basin.