歧口凹陷埕北断阶带油气输导体系及其控藏作用

Hydrocarbon Migration Pathways and Its Control on Accumulation in Chengbei Fault Zone of Qikou Sag,Bohai Bay Basin,East China

受构造与沉积作用影响,埕北断阶带形成断层-砂体-不整合复杂输导网络体系,影响油气运移和聚集.基于地震、录井、测井资料,刻画研究区输导格架样式及展布特征,依据油气分布及原油物化性质明确优势输导体系及控藏作用.结果表明,在沙一段顶部-东营组、明化镇组两套区域性泥岩盖层分割下,垂向上形成沙三段-沙二段-沙一下亚段、馆陶组-明化镇组输导层,与断层匹配组成上、下二元输导格架,chh24、h4井区是油气突破东营组盖层向上部输导层跨越的泄露点.平面上存在4大输导格架带:歧南次凹-友谊-刘官庄沙三段、沙一段、馆陶组;中低断阶中部沙二段、沙一段、馆陶组;歧南-中断阶沙三段、沙二段、沙一段;张东东井区沙三段、沙二段、馆陶组输导格架带.油气富集特征及物化性质证实,输导格架带内局部构造高点控制油气优势运移指向,示踪的4条优势输导体系形成油气规模充注通道,二元输导格架控制油气“阶状”富集模式.中低断阶中部沙二段与沙三段、高斜坡馆陶组与明化镇组阶梯式油气勘探存在较大潜力,相关认识有助于相似区域油气深入挖潜.

Influenced by tectonics and sedimentation,the complex pathway networks developed in ChengBei Fault Zone,consisting of faults,sand bodies and unconformities,which controlling petroleum migration and accumulation.Based on the seismic and logging data,the carrier networks were characterized systematically through the analysis on the transport performance of faults,sand bodies and unconformable surfaces in this paper.And the preferential migration pathways of hydrocarbon were traced by understanding the distribution and the physical and chemical properties of petroleum.The results showed that the two carrier layers were formed vertically,namely the third member-the second member-the lower part of the first member in Shahejie Formation,and the Guantao-Minghuazhen Formation,which were cutted by mudstone capcocks of the top part of Shahejie Formation and Dongying Formation,and Minghuazhen Formation.Chh24、h4 well areas are the leakage parts of hydrocarbon breaking through the upper part of the Dongying cap rock into the carriers of Guantao-Minghuazhen Formation.Horizontally,fault,sand body and unconformity surface constitute four major carrier belts:the first-third member of Shahejie Formation and the Guantao formation in Qinan Subsag and the areas of Youyi-Liu guanzhuang;the first-second member of Shahejie Formation and the Guantao formation around the lower and middle Chengbei Fault zone;the first-second-third member of Shahejie Formation from Qinan Subsag to the middle part of Chengbei Fault zone;the second-third member of Shahejie Formation and the Guantao formation in Zhang Dongdong areas.In these carrier belts,petroleum was enriched into structural ridges or monoclinal high points,which controlling the dominant migration direction.The composition of nitrogen compounds and the physical properties revealed that four potential migration pathways existed inside four major carrier belts respectively,developing main charging channels on a large scale."Ladder" accumulating mode in ChengBei Fault Zone are mainly controlled by dual transport framework and four prefential migration pathways.Accordingly,the second-third member of Shahejie Formation in lower and middle part of ChengBei Fault Zone,and Guantao-Minghuazhen Formation in the high slope part are chosen as the potential areas,which will be beneficial to further discovery in similar areas.