济阳坳陷惠民凹陷沙三段地震事件沉积特征及地质意义

Sedimentary characteristics and geological significance of earthquake events of Sha 3 member in Huimin Sag,Jiyang Depression

为研究济阳坳陷惠民凹陷沙三段古地震事件沉积特征及其控藏作用,开展了钻井岩心观察、震积岩单井垂向序列划分、沉积主控因素分析和古地震事件地质意义研究。结果表明:①惠民凹陷沙三段沉积地层中,震积岩构造十分发育,包括震裂、自碎角砾、阶梯状小断层、液化岩脉、液化卷曲、液化角砾和其他脆塑性变形构造。②地震强度、沉积物固结程度和地形坡度均是影响震积岩发育的主要因素,多口井的垂向沉积序列显示,研究区不同构造位置的震积岩发育特征存在差异,可分为4个区域,分别为近震源平缓区、主震区、近震源坡度区、远震源平缓区。③地震事件沉积研究为惠民凹陷断层活动速率、生长指数等参数的确定提供了依据,且地震事件是激发砂体二次运移的重要动力源;地震事件中的震动可造成未固结的沉积物发生颗粒重排,降低沙三段储层的非均质性。④断层附近丰富的脆性震积构造可能成为油气运移的辅助通道,地震形成的自碎角砾岩为良好的储集层,液化均一的压实层为优质盖层。该研究成果对惠民凹陷震积岩油气勘探具有重要的指导意义。

In order to study the sedimentary characteristics of paleoearthquake events in the third member of Shahejie Formation in Huimin Sag of Jiyang Depression and its reservoir controlling effect,core observation,vertical sequence division of single well of seismic sedimentary rocks,analysis of main controlling factors of sedimentation and geological significance of paleoearthquake events were carried out.The results show that:(1)The structure of seismites is very well developed in the third member of Shahejie Formation in Huimin Sag,including shatter crack,autoclastic breccia,stepped small fault,liquefied vein,liquefied curl,liquefied breccia and other brittle plastic deformation structures.(2)Seismic intensity,sediment consolidation degree and terrain slope are the main factors affecting the development of seismites.The vertical sedimentary sequence of several wells shows that the development characteristics of seismites in different structural positions in the study area are different,which can be divided into four areas,namely near source gentle area,main seismic area,near source slope area and far source gentle area.(3)The study of earthquake event deposition provides a basis for the determination of fault activity rate,growth index and other parameters in Huimin Sag,and the seismic event is an important power source for stimulating the secondary migration of sand body.The vibration in seismic event can cause the particle rearrangement of unconsolidated sediments,and reduce the heterogeneity of the reservoir in the third member of Shahejie Formation.(4)The abundant brittle seismites near faults may be the auxiliary channel of oil and gas migration,the autoclastic breccia formed by earthquakes is a good reservoir,and the compacted layer with uniform liquefaction is a high-quality caprock.The results of this study are of great significance to seismic exploration in Huimin Sag.