东海陆架盆地西湖凹陷中北部花港组储层致密化过程分析

综合运用薄片鉴定、扫描电镜、恒速压汞、X衍射、流体包裹体测温、激光拉曼成分分析及伊利石同位素测年等技术方法，分析了东海陆架盆地西湖凹陷中北部花港组储层致密化过程，并探讨了储层致密化控制因素。花港组储层非均质性受孔喉结构控制，喉道半径小于1 μm即为致密储层；埋藏压实是储层普遍低渗、致密的主因，差异成岩作用加剧了储层的差异演化，当地温超过160℃，环边绿泥石对胶结作用的抑制明显减弱，中成岩B期碱性封闭环境使得大量含铁碳酸盐、绒球状绿泥石及搭桥状伊利石富集直接堵塞喉道，造成花港组储层规模性致密。对花港组储层关键成岩期演化过程进行恢复，推测花港组H4、H5砂层组在9~7 Ma进入规模性致密，龙井运动强烈侧向挤压加速了致密化进程。 

Densification process of Huagang Formation in northern and central Xihu Sag of East China Sea Shelf Basin

Technical methods such as cast thin section identification,scanning electron microscopy,constant rate mercury intrusion,Xray diffraction,fluid inclusion homogenization temperature measurement,laser Raman component analysis and illite isotope dating were used to analyze the densification process of Huagang Formation in the northern and central Xihu Sag of the East China Sea Shelf Basin.The controlling factors of reservoir densification were discussed.The reservoir heterogeneity of the Huagang Formation is controlled by the pore throat structure,and the reservoir with a throat radius less than 1μm is regarded as a tight reservoir.Burial compaction is the main reason for the generally low permeability and tightness of reservoirs,and differential diagenesis aggravates the differential evolution of reservoirs.When the formation temperature exceeds 160℃,the inhibition of cementation by the ring chlorite is significantly weakened.The alkaline closed environment of the middle diagenesis B stage makes a large amount of ironcontaining carbonate,pomshaped chlorite and bridging illite enriched and directly blocks the throats,resulting in largescale tight reservoirs in the Huagang Formation.Recovering the key diagenetic evolution process of the Huagang Formation reservoirs,it is speculated that the H4 and H5 sand formations of the Huagang Formation entered largescale compaction during 9-7 Ma,and the strong lateral compression of the Longjing Movement accelerated the densification process.