山东东营凹陷古近系碎屑岩储层特征及控制因素

Clastic reservoir properties and their controlling factors of the Paleogene in Dongying Sag,Shandong Province

通过对大量储层物性数据的分析和整理 ,结合薄片观察和扫描电镜分析结果 ,研究了不同构造背景、不同沉积类型及不同埋深的储层物性特征及其控制因素。东营凹陷古近系碎屑岩储层类型多样 ,大多形成在冲积扇 -河流、扇三角洲、近岸水下扇、深水浊积扇、三角洲前缘滑塌浊积扇以及滨浅湖滩坝等多种沉积环境中。碎屑岩储层类型主要包括砾岩、含砾砂岩、中粗砂岩、细砂岩及粉砂岩。其中中砂岩和细砂岩是最好的储层。但是不同地区、不同类型储层物性存在较大的差异。物性最好的储层为河道、 (扇 )三角洲前缘水下分流河道及河口坝砂体。在相同深度条件下 ,中央隆起带的物性最好 ,北部和南部次之。另外 ,本区随埋藏深度增加 ,碎屑岩储层物性逐渐变差 (剔除次生孔隙的影响 )。根据碎屑岩储层物性差异性分析和储层成岩演化研究结果 ,其储层物性主要受压实作用、碳酸盐溶蚀与胶结作用及沉积条件四大因素控制 ,其中压实作用、溶蚀作用及胶结作用是主要控制因素 ,而沉积条件对物性的影响主要表现在控制原生孔隙的发育程度 ,并进一步控制溶蚀、胶结等成岩作用。

Reservoir properties and their controlling factors in different tectonic settings,sedimentary environments and burial depth are studied by analyzing a large amount of data of reservoir properties,combined with thin-section petrography and scanning electron microscopic(SEM)analysis.There are many types of clastic reservoir rocks in the Paleogene of Dongying Sag,mostly formed in different sedimentary environments,such as alluvial fan,river,fan delta,near-shore subaqueous fan,deep-water turbidite fan,delta-front slump turbidite fan,shore-shallow lake bar and so on.Clastic reservoir rocks consist of conglomerate,pebbly sandstone,medium-coarse sandstone,fine sandstone and siltstone,of which medium sandstone and fine sandstone are the best reservoir rocks.Reservoir properties of rocks in different sedimentary facies and areas are different.Reservoir rocks in fluvial,(fan)delta-front subaqueous distributary channel and mouth bar,have the most effective reservoir properties.Central uplift zone has better reservoir properties than north steep-slope zone and south slope zone at the same burial depth.In addition,reservoir properties are getting worse and worse with increasing burial depth(influence of secondary pores are not taken into account).Based on the analysis of reservoir properties and diagenetic,the reservoir properties of clastic rocks in Dongying Sag are dominated by four factors,namely compaction,carbonate dissolution,cementation,and sedimentary conditions.Among them,compaction and diagenetic degree(the relative degree of dissolution and cementation)are main factors.The effect of sedimentary conditions on reservoir properties manifests the development of primary pore,and its control on dissolution and cementation.