渤海海域沙一段基底岩性条件对湖相混积岩储层的控制作用

渤海湾盆地渤海海域沙一段发育湖相碳酸盐岩与碎屑岩混积岩，勘探实践表明，湖相混积岩在深埋条件下可以保持较高的物性，产能也较高，渤海海域目前发现的混积岩探明储量超过3×108 m3.研究通过地质条件比对，结合薄片、同位素、元素分析、物理模拟实验，提出火山岩基底条件是湖相混积岩规模发育的重要控制因素之一.火山岩基底包括中生界火山岩基底、古近系火山岩基底、以火山岩为母源的沉积体基底3种类型.模拟实验表明，火山岩中的暗色矿物大量水解，会导致周边水体富含矿物质，矿物质富集导致藻类等微生物勃发，进而形成以藻类为食的生物群落的发育，为生屑的大量富集提供了条件.扫描电镜下见白云岩化丝状蓝细菌及球状白云岩，证实在沙一段混积岩存在准同生生物白云岩化作用，早期白云岩化作用有利于储层物性的保持，让后期白云岩化作用有了成核基础，促进了后期白云岩化.火山岩岩屑（砾石）铸模孔和内部溶蚀孔占整体储集空间的10%~30%，对储层物性贡献较大.溶蚀模拟实验证实，火山岩的暗色矿物水解溶蚀可提供Mg2+离子，对埋藏白云岩化作用具有促进作用. 

Impacts of Basement Lithology on Reservoir of Lacustrine Carbonate and Clastic Mixed-Deposition in Member l of Shahejie Formation,Bohai Sea Area

Lacustrine carbonate and clastic mixed-deposition is developed in member 1 of Shahehjie Formation of Bohai Sea area, Bohai Bay basin. Exploration practice indicates that lacustrine mixed-deposition at deep burial depths is higher in production capacity, with proved reserves of more than 3×108 m3, since it can retain higher physical properties. In this paper, it proposes that volcanic rock basement is one of the important factors of mixed-deposition scale development, based on the geological analyses, combined with thin section, isotope, and elemental analyses, and physical simulation experiment. Volcanic rocks in the basement consist of the following three types:the Mesozoic volcanic rock basement, Paleogene volcanic rock basement, and sedimentary bodies with provenance from the volcanic rocks. Simulation experiments show that the dark minerals in the volcanic rocks in the hydrolysis process can lead to enriched metal ions in surrounding waters, and as a result, microbes arise and microbial ecological community develops, which provides conditions to enrichment of bioclastics. The discovery of dolomization filamentous cyanobacteria and globular dolomite affirms the existence of penecontemporaneous biological dolomization in mixed-deposition. Early dolomization is advantageous to the reservoir property and the late dolomization, facilitating the nucleation for later dolomization. Volcanic rock lithic fragment (gravel) internal mould pores and dissolution pores account for 10%-30% of reservoir space, with significant contribution to reservoir property. Dark mineral dissolution simulation experiments confirm that volcanic hydrolysis solution can provide Mg2+ ions, which facilitates the burial dolomization.