莱州湾凹陷东缘走滑断裂带特征及沉积响应

Characteristics of Strike Slip Fault Zone in the Eastern Margin of Laizhou Bay Sag and Their Sedimentary Response

为了弄清莱州湾凹陷东缘走滑断裂带特征及其与沉积响应的关系,利用三维地震、钻井、测井等资料,通过统计断裂活动速率、派生断裂发育数量及延伸长度,定量分析了莱州湾凹陷东缘古近纪走滑活动特征,结合储层类型统计、砂体平面分布及古地貌特征,探讨了走滑断裂带对沉积的控制作用。研究表明,走滑活动在古近纪具有分期、分段活动特征。东三期走滑最强,沙一二期和沙三期次之。东三期不同位置断裂走滑活动具有差异性,从南到北走滑强度逐渐减弱,储层厚度逐渐减薄。分期走滑活动控制沉积体展布方向及规模大小,决定差异控砂模式。弱走滑期坡折控砂,富砂区相对固定,沉降中心及反向断槽等处砂体富集;强走滑期走滑活动使同期形成的沉降中心、沉积体随时间发生横向迁移,形成纵向多期发育、横向迁移叠覆的砂体分布样式,洼陷区沉降中心、斜坡区拉分沟槽为主富砂区发育位置。

In order to clarify the characteristics of strike-slip fault zone in the eastern margin of Laizhou Bay Sag and its relationship with sedimentary response,the characteristics of Paleogene strike-slip activities in the eastern margin of Laizhou Bay Sag were quantitatively analyzed by using three-dimensional seismic,drilling and logging data,together with statistical analysis of fault activity rate and the number and extension length of derived faults.The controlling effect of strike-slip fault zone on sedimentation was discussed according to the analysis results,the statistics and distribution of reservoir types,the plane distribution of sand bodies and palaeogeomorphological characteristics.The research results show that the strike slip activities are characterized by stages and subsections in Paleogene.The strongest strike-slip activities occurred in the third stage of Dongying Formation,followed by the first,second and third stages of Shahejie Formation.In the third stage of Dongying Formation,the strike-slip activities of faults at different locations are different,and the strike-slip activity intensity and the reservoir thickness decrease gradually from south to north.Phased strike-slip activities control the distribution direction and size of sedimentary bodies,and determine differential sandbody control pattern.During the weak strike-slip activity period,the slope break controls sandbody,the sandbody-rich area is relatively fixed,and the sand bodies are more enriched in the settlement centers and reverse fault troughs.During the strong strike-slip activity period,the strike-slip activities make the sedimentation centers and sediment bodies formed in the same period migrate transversely with time,forming the sandbody distribution pattern of longitudinal multiphase development,transverse migration overlapping,and the sandbody enrichment areas are mainly in the subsidence center of subsags and the pull-apart trough of slope areas.