辽西低凸起JZ油田沙二段古地貌特征及其对沉积的控制作用

Paleogeomorphologic Characteristics of 2nd Member of Shahejie Formation of JZ Oilfield in Liaoxi Low Uplift and Its Control On Sedimentation

渤海辽东湾海域JZ油田处于辽西低凸起西侧倾末端,受其复杂古地貌影响,沙二段沉积特征极为复杂,储层展布规律不明确。为了明晰古地貌特征及其对沉积的控制作用,将高分辨率层序法与层拉平法相结合,对研究区沙二段沉积前古地貌进行恢复,识别古地貌单元及其组合规律,并分析古地貌对沉积的控制作用,从成因上刻画沙二段辫状河前缘砂体展布。结果表明:研究区沙二段沉积前发育古沟谷、古构造脊及古斜坡等3类古地貌单元,在平面上形成被构造脊遮挡的深沟谷带、被构造脊分隔的浅沟谷带及斜坡沟谷带3种组合。综合古地貌与古物源对沉积的控制作用,分别建立上述3种古地貌组合下的沉积模式——水下分流河道主控型辫状河三角洲、多朵叶型辫状河三角洲及单朵叶型辫状河三角洲,并总结不同辫状河三角洲砂体的开发产能规律。

JZ oilfield in Liaodong Bay of Bohai Sea is located at the west dip end of Liaoxi low uplift.Affected by its complex paleogeomorphology,the sedimentary characteristics of Sha 2 member are very complex,and the reservoir distribution law is not clear.In order to clarify the characteristics of ancient geomorphology of JZ oilfield and its control on sedimentation,by combining high-resolution sequence method and layer leveling method,the paleogeomorphology before ES 2 deposited in the study area is restored,the paleogeomorphic units and their combination law are identified,the control effect of paleogeomorphology on sedimentation are analyzed,and the distribution of braided river fronts and-bodies in ES 2 is characterized in terms of genesis.The results show that there were developed three types of paleogeomorphic units,ancient valley,ancient structural ridge and ancient slope,before ES 2 deposited in the study area,and three paleogeomorphic unit combinations on the plane,deep valley belt covered by structural ridge,shallow valley belt separated by structural ridge and slope valley belt.Comprehensively considering the control of ancient geomorphology and ancient provenance on sedimentation,three sedimentary models,braided river delta dominated by underwater distributary channel,multi-leaf braided river delta and single-leaf braided river delta,are established respectively under the above three paleogeomorphic unit combinations,and the development production capacity laws of different braided river delta sand bodies are summarized.