莫索湾地区三工河组一段储层特征及有效物性下限

Characteristics and lower limit of physical properties for reservoirs of 1st Member of Sangonghe Formation in Mosuowan area

物性下限是识别致密储层、确定油层厚度的关键参数。莫索湾地区侏罗系三工河组一段致密储层物性下限一直悬而未定,严重影响了该区致密油的勘探和开发。在非常规油气理论指导下,文中基于测录井资料,观察并统计大量岩石薄片数据,运用CT扫描等手段,对研究区致密储层特征进行了分析,并综合运用试油法、J函数法厘定了储层的有效物性下限。结果表明:莫索湾地区三工河组一段总体为多期叠置的水下分流河道,属于三角洲前缘亚相;岩性主要为长石岩屑砂岩,其次为岩屑砂岩;颗粒成分成熟度较低,以细粒为主;孔隙类型以颗粒次生的溶蚀孔为主;储层致密且物性差,平均孔隙度9.33%,平均渗透率0.48×10^(-3)μm^(2);有效储层孔隙度下限为9.20%,渗透率下限0.30×10^(-3)μm^(2),最小流动孔喉半径0.34μm。

The lower limit of physical property is a key parameter for identifying tight reservoir and determining reservoir thickness,and the lower limit of physical property of the tight reservoir in the 1 st Member of Sangonghe Formation of Jurassic has been unsettled, which has seriously affected the exploration and development of tight oil in Mosuowan area. According to the guidance of unconventional hydrocarbon theory, based on the well-logging, drilling, thin-section and CT data, the characters of tight reservoir beds have been analyzed. The lower limit of effective physical properties of the tight reservoir beds has been ascertained, according to the oil testing and Function J. The results show that the underwater channel sand-body with multi-episodes are the main sandstone reservoirs in the 1 st Member of Sangonghe Formation in Mosuowan area, belonging to delta front subfacies;the lithology is mainly feldspathic, followed by litharenite;litharenite has low composition maturity, and fine grains were the main type;the secondary pores are main type;the tight reservoir has permeability, with the mean porosity of 9.33% and the mean permeability of 0.48×10^(-3)μm^(2);the lower limit of porosity, permeability, and throat radius for the effective reservoir beds are 9.20%, 0.30×10^(-3)μm^(2), and 0.34 μm.