北黄海盆地是我国近海勘探及研究程度均较低的中新生代叠合断陷盆地,下白垩统砂岩储层是主要的勘探目的层段,储层致密是制约该区油气勘探的“瓶颈”之一.通过岩心观察、薄片分析、扫描电镜观测、压汞分析、物性统计等研究,对北黄海盆地东部坳陷下白垩统的储层特征进行了研究,从沉积、成岩、埋藏史等方面对其致密化成因进行了探讨.结果表明,下白垩统储层以扇三角洲沉积为主,物性总体较差,属于特低孔特低渗的致密砂岩储层,储集空间主要有粒间溶孔、粒内溶孔、微裂缝等次生孔隙,属孔隙-裂缝双孔介质储层,孔隙结构复杂.该储层特征主要受沉积相带、成岩作用及埋藏史等因素控制,储层砂体以长石岩屑砂岩、岩屑长石砂岩为主,成分及结构成熟度中等,原始储层物性差,高含量的塑性岩屑不利于原生孔隙的保存,沉积物粒度决定微裂缝的发育程度.成岩作用起主导作用,受早期深埋-中期抬升剥蚀-晚期再次深埋的这一特定埋藏过程影响,早期强烈压实,后期石英自生加大、方解石胶结、自生矿物晶出等胶结作用导致储层整体致密.长石的溶蚀和粘土化促进了次生孔隙的形成,但烃类充注时间晚、酸性流体活动弱,溶蚀作用受到抑制.后期构造作用产生的微裂隙则是改善储层物性的另一重要作用. The North Yellow Sea Basin is a Mesozoic-Cenozoic superimposed and subsidence basin with relatively low level of exploration and research in offshore China. Lower Cretaceous sandstone reservoirs are the main exploration target reservoirs, and tight reservoirs are the bottleneck restricting oil and gas exploration in this area ".Through the study of core observation, thin slice analysis, scanning electron microscope observation, mercury intrusion analysis, physical statistics and other research, the reservoir characteristics of the Lower Cretaceous in the eastern depression of the North Yellow Sea Basin were studied, from the sedimentary, diagenetic, burial history Etc. The results show that the Lower Cretaceous reservoirs are mainly fan delta sediments with poor overall physical properties, which belong to the tight sandstone reservoirs with ultra-low permeability and ultra-low permeability. The reservoirs mainly contain grains Intergranular dissolved pores, intragranular dissolved pores, micro-cracks and other secondary pores, is a pore-fracture dual porosity reservoir, pore structure is complex. The reservoir characteristics are mainly controlled by sedimentary facies, diagenesis and burial history and other factors, storage The layered sand bodies are mainly feldspathic lithic sandstones and lithic feldspar sandstones, and their composition and structure are of medium maturity. The physical properties of the original reservoirs are poor. The high content of plastic rock fragments is not conducive to the preservation of primary pores. The sediment grain size determines the microcracks The degree of development. The rock plays a leading role. Due to the early burial - mid-term uplifting and denudation - the later deep burial, this particular burial process strongly compacted at early stage, increased self-generation of later quartz, cementation of calcite and mineralization of authigenic minerals The dissolution and calcification of feldspar promoted the formation of secondary pores, but the hydrocarbon charge was late, the acid fluid activity was weak, and the dissolution was inhibited.The micro-fissures produced by the later tectonics were the measures to improve the reservoir physical properties Another important role.