火成岩风化壳储集层特征与油气产能关系研究:以准噶尔盆地红山嘴石炭系油藏为例

红山嘴油田是准噶尔盆地典型的风化壳型油藏,具有广阔的勘探前景。利用宏微观岩矿分析、地球物理、地球化学等多种实验分析手段,对红山嘴地区火成岩岩石学特征、结构发育特征及控制因素开展综合研究,结果表明:(1)红山嘴地区发育侵入岩、次火山岩、火山熔岩、火山碎屑熔岩、火山碎屑岩和沉火山碎屑岩等6大类火成岩,其中安山岩和凝灰岩最为发育;(2)火成岩储集空间组合包括原生气孔—溶蚀孔—Ⅰ级裂缝型、溶蚀孔—Ⅰ/Ⅱ级裂缝型、Ⅲ级裂缝型和Ⅳ级裂缝型4类,Ⅰ—Ⅳ类储层物性依次变差;(3)风化壳自上而下发育水解带、淋蚀带、崩解Ⅰ带、崩解Ⅱ带、母岩带5个分带,顶部水解带风化强,多被分解成致密的泥土层,可作盖层,而淋蚀带和崩解Ⅰ带是风化淋蚀改造较好区,储层物性最好;(4)不同油气产能井与风化壳结构具有很好的对应关系,可为风化壳型火成岩油藏优势区带划分和产能预测提供指导。

Characteristics of Igneous Weathering Crust Reservoir and Its Relation With Oil and Gas Productivity: A Case Study of the Carboniferous Hongshanzui Reservoir,Junggar Basin

The Hongshanzui oilfield is a typical weathering crust reservoir in the Junggar Basin, and has substantial prospect for exploration. This study uses macro-/micro-lithological and mineral analyses, geophysics, geochemistry and other experimental techniques to comprehensively study the petrological and structural features and controlling factors of igneous rocks at Hongshanzui. The results show that:(1) There are six types of igneous rocks at Hongshanzui: intrusive rocks, subvolcanic rocks, volcanic lava, pyroclastic lava, pyroclastic rock and sed-volcanic pyroclastic rock, among which andesite and tuff are the most developed; (2) Reservoir space combination of igneous reservoir includes primary pore-dissolution pore-level I, dissolution pore-level I /Ⅱ, level Ⅲ and level IV fracture types, with the physical properties deteriorate from level I to IV reservoirs; (3) The weathering crust develops a five-layer structure from top to bottom: hydrolysis zone, leached zone, break-down zone I, break-down zone Ⅱ and the underlying bedrock. The hydrolysis zone on the top is commonly decomposed into a dense soil layer, which can serve as a cap. Besides, the leached zone and the break-down zone I show better weathering and leaching transformation, hence the reservoir has the best physical properties; (4) Different oil and gas productivity wells have a good corresponding relationship with the weathering crust structure, which can guide the division of the dominant zone for the weathering crust igneous rock reservoir and the related productivity prediction.