箕状断陷湖盆缓坡带储集砂体特征、演化及控制因素——以胜利油区东营凹陷南缓坡带沙河街组为例

Characteristics, Evolution and Controlling Factors of the Terrigenous Clastic Reservoir Sand Bodies on the Gentle Slope Zone of the Half-Graben Rift Lake Basin——A Case Study of the Shahejie Formation on the Southern Gentle Slope Zone of the

胜利油区东营箕状断陷湖盆南部缓坡带沙河街组主要沉积学特征及地球物理特征为①冲积扇 :由含砾砂岩 ,细粒不等粒 (类 )砂岩、粉砂岩、泥质粉砂岩组成 ,在测井曲线扇根为高幅齿化的箱形和钟形 ,扇中为中幅的分散齿形或钟形特征 ,斜交前积结构 ,扇端为低幅分散的齿形特征 ,为亚平行反射同相轴 ,地震相特征扇根内部反射是一杂乱 短波形 ;②河流相砂体 :由多种粒级的砂岩、砂质砾岩、粉砂岩和灰色及紫红色泥岩等组成 ,测井曲线下部旋回表现为箱形 钟形特征 ,上部旋回为平行于泥岩基线夹指形曲线为特征 ,在地震反射上常表现为槽形充填特征 ,内部为短波状 -杂乱状反射或为中振中连亚平行反射 ;③三角洲砂体 :由含砾砂岩、砂岩、粉砂岩及泥质粉砂岩、泥岩、碳质页岩组成 ,测井曲线上三角洲平原亚相表现为高幅钟形 (底部呈突变接触 ) ,三角洲前缘在自然电位曲线上表现为漏斗型负异常 ,视电阻率曲线上为低幅锯齿状 ,前三角洲亚相为光滑的平直曲线夹小段的微齿状曲线 ;④滨浅湖砂坝砂体 :由灰绿色粉砂岩、细砂岩及少量含砾砂岩组成 ,测井曲线上表现为倒钟形和钟形的组合或指形或圆滑箱形、或锯齿状 ,在地震反射上就表现为亚平行、中振幅、中连续、中频、中丰度 ,平坦的或局部有波状起伏的席状反射结构 ;

This paper presents a case study of Shahejie Formation on the southern gentle slope zone of Dongying half-graben rift lake basin in the Shengli Oil Field. The sedimentological and geophysical features of Shahejie Formation can be generalized into five types: ① Alluvial fan: It is composed of pebbled sandstone, seriate poststone, siltite and pelitic siltstone. On the well log, the fan root assumes the shape of high amplitude box and bell, the middle fan shows middle amplitude disperse dental or bell form, and the front fan is of low amplitude disperse dental form. On seismic facies, the fan root assumes random short wave.② Sand body of fluvial facies: It is composed of seriate sandstone, sandy gravel, siltstone and gray or purple mudstone. On the well log, it changes regularly from the lower part cycle to the upper part cycle. The lower part cycle is box-bell-shaped whereas the upper part cycle is a parallel mudstone baseline on seismic reflection. It shows trough filling and internally assumes short wave random reflection or middle amplitude parallel reflection. ③Sand boby of delta: It is composed of pebbled sandstone, sandstone, siltite, pelitic siltstone, mudstone and carbonaceous shale. On the well log, the delta plain shows high amplitude bell shape, with the bottom being the surface of discontinuity. The delta front assumes funnel-shaped negative anomaly on the spontaneous potential curve. It shows low amplitude zigzag form on the apparent resistivity curve. The prodelta shows smooth flat curve intercalated with short sectors of dental curves. ④Sand body of beach shallow lake: It is composed of gray-green siltite, poststone and pebbled sandstone. On the well log, it shows such forms as the combination of inverted clock and bell, finger, smooth box or zigzag shapes. On seismic reflection, it assumes subparallel, intermediate abundance, flat and wavy bar reflection configurations.⑤ Sand body of gentle turbidity: It is composed of pebbled sandstone, sandstone siltite and mudstone. On the spontaneous potential curve, it shows box-washing-fingerlike-zigzag form. On the seismic profile, it assumes upper form or foreset form reflection. On the basis of the above studies, this paper deals with the time-space evolution regularity of various sand bodies and the factors controlling their development.