歧北凹陷古近系构造坡折带对圈闭的控制作用

Control of Paleogene structural slope-break on non-structural traps in the Qibei Sag,Bohai Bay Basin

应用三维地震、钻井和测井等资料,对歧北凹陷进行层序地层学研究。研究区古近系可划分为3个二级层序,11个三级层序。歧北凹陷斜坡区发育断裂坡折和挠曲坡折两种构造坡折带类型。坡折带的发育演化具有明显的阶段性和继承性:早期为断裂坡折带,晚期为挠曲坡折带。不同类型坡折带层序构成样式及内部体系域构成不同,断裂坡折带控制了低位扇三角洲砂体以及构造-岩性复合圈闭的发育,而挠曲坡折带除了对砂体有控制作用外,更突出地表现为对地层超覆以及岩性圈闭发育的控制。坡折带附近是非构造圈闭发育的有利部位,进一步勘探的潜力巨大。

The study of sequence stratigraphy is carried out in central Huanghua Depression using 3D seismic data,drilling,and well logging data.The Paleogene of the studied area can be divided into three second-order sequences,and 11 third-order sequences.Two kinds of structural slope-break are developed in the Qibei slope： faulted slope-break and flexural slope-break.The development and evolution of the slope-breaks are episodic and successive： in early period,it is faulted slope-break;in later period,it is flexural slope-break.Different kinds of slope-breaks have different sequence stratigraphic patterns and inner systems tracts.The faulted slope-breaks control the development of lowstand fan delta sandbodies and combination structural-lithologic traps,while the flexural slope-breaks not only control the development of sandbodies,but more apparently control the development of stratigraphic overlap and lithologic traps.The surrounding areas of the slope-breaks are favorable for the development of non-structural traps,and have great potential for exploration.