酒西盆地中新生代碎屑组分特征及指示意义

通过岩石碎屑成分分析,研究酒西盆地砂砾岩储集层沉积碎屑成分特征对物源属性、盆-山格局演化及油气成藏特征的指示意义。研究表明,酒西盆地下白垩统下沟组砂岩成分成熟度低,物源构造属性以再旋回造山带和部分岩浆弧为特征,物源岩石类型主要为中酸性岩浆岩和变质岩(沉积岩碎屑极少),岩石成分及其组合显示盆地东、西部的物源差异明显;古近系白杨河组在岩石成分、岩屑组成上与下白垩统下沟组砂岩有较大不同,显示物源属性的明显改变。物源属性的改变在一定程度上反映构造格局分异、盆-山格局的演变历程,控制了酒西盆地内油气富集和晚期成藏特征。碎屑成分特征在一定程度上决定了储集层的储集空间类型及裂缝发育规律,值得进一步深入研究。

Clastic composition of Mesozoic-Cenozoic reservoirs in the western Jiuquan Basin: Implications for evolution of basin-range pattern and hydrocarbon accumulation

The study of detrital composition of sandstones is an important method for understanding provenance types,basin-range evolution and tectonic attributes.The sandstone framework grains of the Xiagou Formation of Lower Cretaceous in western Jiuquan Basin generally show low detrital maturity,characterized by source from recycled orogen and part of magmatic-arc.The Xiagou Formation mainly consists of provenances of metamorphic and intermediate acidic volcanic(few sedimentary rocks).The detrital compositions show obvious differences in provenance between the western and eastern area of western Jiuquan Basin.The detrital composition of Baiyanghe Formation is very different from that of Xiagou Formation,implying the changes in provenance attribute.Combined with previous research results,the changes in provenance attribute reflect the evolution of tectonic diversity and basin-range pattern,which control the oil and gas enrichment and the late hydrocarbon accumulation in western Jiuquan Basin.The detrital composition that controls the reservoir space and development law of fractures is worthy of further study.