渤海湾盆地潍北凹陷孔三段中基性火山岩储层特征及控制因素

Characteristics and Controlling Factors of the Intermediate and Mafic Volcanic Reservoirs of the Paleogene Kongdian Formation in the Weibei Sag of the Bohaiwan Basin

在综合火山岩岩心观察、薄片鉴定、测井资料、地震资料分析的基础上,从火山岩岩性、岩相特征、孔隙类型、储层物性等方面研究了潍北凹陷孔三段火山岩储层特征,分析了火山岩储层储集空间类型、物性特征和储层物性的主要影响因素。研究结果表明:区内火山岩为中基性火山岩,以玄武岩为主,偶见少量火山碎屑岩,主要为火山角砾岩;岩相类型主要包括溢流相、火山通道相和火山沉积相等类型,以喷溢相最为发育;火山岩的分布受深大断裂和古地形共同控制,具垂向多期叠置、平面分布广泛的特点。储集空间类型分为孔隙和裂缝,以原生气孔、杏仁体内孔、构造裂缝和风化溶蚀缝等为主。储层物性受火山岩的岩相、构造活动、风化淋滤作用和矿物充填作用的影响。火山溢流相上部亚相原生孔隙最发育,但多彼此孤立存在,在多期构造运动和风化淋滤等作用下火山岩储集性能够得到极大改善,裂缝、孔隙叠合发育的火山岩是有效火山岩储层。

Based on the core observation, thin section identification, and integration of well log and seismic data, we analyzed lithologic characteristics, lithofacies characteristic, pore type, reservoir physical property of the Third Member of Kongdian Formation in the Weibei sag.The results indicate that the volcanic reservoir rocks are mainly composed of the intermediate and mafic volcanic rock, the lithology of the study area is dominate by the thick basalt and thin volcanic breccia. Effusive facies, volcanic vent facies and volcanogenic sedimentary facies can be identified, with effusive facies well developed and widely distributed. The distribution of volcanic rocks are mainly affected by deep faults and paleotography. The types of reservoir spaces can be divided into pore and fracture, with primary pores, apricot kernel inner pore, structural fractures and weathering dissolution fracture. Reservoir property is controlled mainly by lithofacies, tectonic action and weathering leaching. Isolated primary pores accumulation in upper subfacies of effusive facies, the reservoir property greatly improved by muti-stage tectonic movement. The favorable volcanic reservoirs developed in the overlapping regions with both fractures and pores.