塔中北斜坡志留系岩性油藏形成条件与勘探方向

Condition and Explorative Direction of Lithologic Reservoir of Silurian in Northern Slope of Tazhong Uplift

对塔中志留系的整体评价与综合研究表明,长期稳定的斜坡背景有利于岩性地层圈闭的形成,潮坪相沉积的砂泥岩薄互层是形成岩性圈闭的地质基础,多期油气充注与调整造成了普遍含油的格局,塔中志留系具有形成大面积、低丰度岩性油藏的地质条件。塔中志留系的勘探要突破局部构造控油的思路,把岩性油藏作为志留系的主要勘探对象;岩性上倾尖灭区是有利的成藏领域;东部志留系岩性相变带、地层超覆带是石油勘探的主战场。

Based on the integral evaluation and composite study of Silurian system in Tazhong uplift, it is indicated that the long-period and stable development of the northern slope setting is favorable for the development of stratigraphic and lithologic traps, and the thin interlayer of sandstone and mudstone in tidal flat sediments is the geologic foundation for forming the lithologic trap. The multistage hydrocarbon accumulation and migration/adjustment create the framework of extensive distribution of hydrocarbons. Hence, the Silurian system in Tazhong uplift possesses the geologic conditions for shaping large-scale and low-abundance lithologic oil reservoirs. The study suggests that exploration of the Silurian must break through the idea of local structure controlling hydrocarbon accumulation. Lithologic reservoirs are the main exploration targets. The updip lithologic pinchout zone is the favorable domain for hydrocarbon accumulation. The facies-varied zone and stratigraphic onlap zone of the Silurian in eastern Tazhong area are the main directions for petroleum prospecting.