沾化凹陷东营组三段储集层特征

Reservoir characteristics of Member 3 of Dongying Formation in Zhanhua Sag

济阳坳陷沾化凹陷东营组岩性油藏勘探近年来获得了较大突破。对东营组三段砂岩储集层沉积演化特征、岩石特征及孔渗特征进行了综合分析,预测其储集层厚度和物性分布规律。沾化凹陷东营组三段为一套扇三角洲沉积体系,储集砂体主要发育在扇三角洲水下分流河道、滩坝、滑塌浊积体等沉积微相内。岩石薄片分析表明,储集层主要属于岩屑质石英砂岩、岩屑砂岩,储集空间以原生孔隙为主,孔隙连通性较好。储集层平均孔隙度为21.15%,平均渗透率为108.08mD,属于中孔中渗储集层。受沉积相的控制,砂岩体呈现凹陷边缘厚、中间薄的特点,岩石物性从凸起向凹陷内具有逐渐变好再变差的分布特征。扇三角洲前缘滑塌成因的湖底扇沉积砂体物性较好,且被周围的浅湖—半深湖相暗色烃源岩包围,是该区东营组最有利的储集砂体。

During the sedimentary period of the Member 3 of the Dongying Formation fan-delta sedimentary system in the Zhanhua Sag, sandstone reservoir primarily appeared in some micro-facies, such as fan-delta subaqueous distributary channel, mouth bar, creeping turbidite. The average porosity and permeability of the sandstone are 21. 15% and 108.08mD, respectively. The distribution of the reservoir thickness and physical properties is controlled by the sedimentary facies, the reservoir on the boundary of the sag is thicker than in the inner, the physical property becomes better and then worse from the boundary to the inner. The thin-section data indicates that the reservoir is primarily lithoelastic quartz sandstone and lithic sandstone, the pore is chiefly primary pores with good communication. The reservoir of the creeping turbidite having good physical properties is surrounded by the source rock of the shallow and semi-deep lacustrine facies, and is the most favorable reservoir of the Dongying Formation.