琼东南盆地崖城地区储层古孔隙面貌恢复

Restoration of paleo-pore features of the sandstone in Yacheng area,Qiongdongnan Basin

关键油气成藏时期的古孔隙面貌对油气成藏至关重要,前人有关琼东南盆地碎屑岩储层特征与埋藏—成岩演化过程—储层物性演变规律—关键油气成藏时期的时空匹配关系以及相关的系统性研究甚少。基于深层优质碎屑岩储层形成过程的全生命周期理论,通过粒度分析、岩石薄片、铸体薄片、X射线衍射、扫描电镜、压汞、物性分析和碳氧同位素分析等多种分析手段,对琼东南盆地崖城地区陵水组、三亚组和梅山组砂岩储层岩石学特征、物性特征、孔隙类型、影响储层物性的宏观作用(物源、海平面变化、坡折带类型、超压)与微观作用(成岩作用)进行了系统分析,并划分了成岩演化阶段与成岩序列;在此基础上,采用成岩序列法,以孔隙度与时间、深度关系为切入点,将孔隙度增减过程与沉积物形成的“源—渠—汇”过程、成岩演化史、埋藏史三者结合,建立了孔隙度随深度和时间演化的关系,明确了崖城地区关键油气成藏时期储层古孔隙面貌。陵水组古孔隙度分布于2.3%~24.1%之间,古渗透率主要分布于(10~600)×10^(-3)μm^(2)之间;三亚组古孔隙度分布于2.6%~28.4%之间,古渗透率主要分布于(100~1 600)×10^(-3)μm^(2)之间;梅山组古孔隙度分布于7.58%~32.62%之间,古渗透率主要分布于(10~500)×10^(-3)μm^(2)之间。同时定量表征了孔隙演化对储层成岩作用强度的响应,以期为该本区中深层油气勘探提供指导。

The paleo-pore features of key oil and gas accumulation period is significant for oil and gas accumulation.However,there are few researches on the relationship between the characteristics of the clastic rock reservoir and burial,diagenetic evolution process,petrophysical property evolution history and key oil and gas accumulation period and the related systematic research.Based on the theory of full-life-cycle research methodology of deep high-quality clastic rock reservoirs,multiple analysis methods such as,grain-size analysis,thin sections,casting thin sections,X-ray fluorescence,scanning electron microscope,mercury porosimetry measurements,petrophysical property analysis,oxygen and carbon isotope characteristics have been applied to systematically analyse the sandstone reservoir petrologic features,petrophysical property,pore structure characteristics and the macro effects (provenance,sea level change,slope break type,overpressure) and micro effects (diagenesis) on reservoir quality from Lingshui Formation,Sanya Formation and Meishan Formation of Yacheng area in Qiongdongnan Basin.Then the diagenetic evolution stage and diagenetic evolution sequence are divided.On this basis,the diagenetic sequence method is used,taking the relationship between porosity and time,depth as the breakthrough point,the process of porosity increase and decrease is combined with the“source-channel-sink”process of sediment formation,diagenetic evolution history and burial history,the relationship of pore evolution with depth and time is established,the paleo-pore features of the reservoir during the key oil and gas accumulation period in Yacheng area are clarified.The paleo-porosity of Lingshui Formation is distributed between 2.3%to 24.1%,and the paleo-permeability mainly ranges from 10×10^(-3)μm^(2)to 600×10^(-3)μm^(2).The paleo-porosity of Sanya Formation is distributed between 2.6%to 28.4%,and the paleo-permeability mainly range from 100×10^(-3)μm^(2)to 1 600×10^(-3)μm^(2).The paleo-porosity of Meishan Formation is distributed between 7.58%to 32.62%,and the paleo-permeability mainly ranges from 10×10^(-3)μm^(2)to 500×10^(-3)μm^(2).The response of pore evolution to reservoir diagenesis intensity is quantitatively characterized,so as to provide guidance for the middle and deep oil and gas exploration in this area.