七里村油田长 6 油层组储层特征及孔隙演化

通过孔渗、压汞、薄片鉴定和扫描电镜等分析资料，以鄂尔多斯盆地七里村油田三叠系延长组长 6油层组储层为研究对象，系统开展了储层特征及孔隙演化等研究。 结果表明：研究区长 6 油层组储层砂岩以细粒长石砂岩为主，矿物成分成熟度低，结构成熟度高；储层呈现出低孔、低渗-特低渗特征。 长 6 储层砂岩总体处于晚成岩 A 期，其经历了强烈的成岩作用改造，孔隙度与渗透率相关性较差。 影响储层物性及孔隙演化的主要因素是机械压实作用、溶蚀作用及胶结作用。 机械压实作用在早成岩期对储层物性影响最大，可使粒间孔隙急剧减小，物性变差。 主要的胶结类型为碳酸盐胶结、石英次生加大及黏土矿物胶结，它们均使得物性进一步变差，而长石、岩屑颗粒及浊沸石胶结物的溶蚀作用改善了碎屑的孔喉结构，加大了次生孔隙空间，是物性得以改善的根本原因。

Reservoir characteristics and pore evolution of Chang 6 oil reservoir set in Qilicun Oilfield

Based on porosity and permeability measurements, mercury penetration, thin section analysis and SEM observations, this paper studied the reservoir characteristics and pore evolution of Chang 6 oil reservoir set of Triassic Yanchang Formation in Qilicun Oilfield, Ordos Basin. The result shows that reservoir sandstones are mainly fine grained arkose sandstone and characterized by low compositional maturity and high textural maturity. Reservoir properties of the study area show low porosity and low to extra-low permeability features. There is poor correlation between porosity and permeability, indicating strong diagenetic reformation of the reservoir sandstones. The Chang 6 reservoir is mainly in late diagenetic A stage. The main factors, influencing reservoir properties and pore evolution, are compaction, dissolution and cementation, among which compaction plays a key role in reservoir property reformation. The main cementation types include carbonate cementation, quartz overgrowth and clay mineral cementation, and they destroyed reservoir pores further. Dissolutions of feldspar, rock debris and laumontite cements widely occurred in the reservoir sandstones, and they increased the secondary pore spaces and improved the reservoir properties.