渤中凹陷石南斜坡区古近系中深层优质储层特征

CHARACTERISTICS OF HIGH-QUALITY RESERVOIR OF MEDIUM-DEEP PALEOGENE IN SHINAN SLOPE AREA,BOZHONG DEPRESSION

运用薄片镜下观察、物性分析、扫描电镜、X衍射及阴极发光等分析手段,对渤中凹陷石南斜坡区古近系中深层储层特征和成岩作用进行了研究。结果表明,渤中凹陷石南斜坡区古近系中深层储层砂岩类型以岩屑长石砂岩和长石岩屑砂岩为主,部分为湖相碳酸盐与陆源碎屑混合沉积。孔隙类型以粒内溶孔和粒间溶孔为主,储集性好,孔隙度一般为20%左右,渗透率为100×10-3μm2～1 000×10-3μm2,为高孔-高渗储层。区内古近系中深层储层中发育有3个次生孔隙发育带,分别为2 500m～2 800m次生孔隙发育带、3 200m～3 400m次生孔隙发育带和3 700m～3 900m次生孔隙发育带。以贫石英、富长石为特征的储层具备了在中深层形成次生孔隙的基础,孔隙演化与成岩演化具有耦合关系,成岩演化是控制储层发育至关重要的因素,溶蚀作用是形成中深部优质储层最重要的建设性成岩作用。

The reservoir characteristics and diagenesis of medium-deep Paleogene in Shinan slope area, Bozhong depression are studied by using thin sections observation, physical properties analy-sis,scanning electron microscope and X-ray diffraction analysis. It is showed that the reservoir sand is dominated by debris arkose and arkose arenite, with some mixed sediments of lacustrine carbonate and continental debris. Intragranular and intergranular dissolved pores are the main pore types in this area,with common porosity of about 20%,permeability of 100×10～μm^2～1000×10^-1μm^2 , belonging to high porosity and high permeability reservoirs. Three secondary pore belts were developed in medium-deep Paleogene reservoir in this area,at the depth of 2500 m ～ 2800 m,3200 m～3400 m and 3700 m～3900 m respectively. The quartz-poor and feldspar-rich reservoirs possess the basis of forming secondary pore in medium-deep layer. Pore evolution and diagenesis are coupling with each other,and diagenesis evolution is the critical factor control-ling reservoir development. Corrosion is the most important constructive diagenesis in the forma-tion of high-quality reservoir in the medium-deep stratigraphy.