火山喷发的多期性是导致凝灰岩潜山纵向多期风化壳（带）发育的重要原因。从地球化学、测井响应特征和岩石学证实了二连盆地凝灰岩潜山多期风化壳（带）的存在及其特征：（1）哈31井凝灰岩地层在1062~1080 m和1165~1179 m两个井段表现为K，Na，Ca等元素淋滤，CIA指数较大，而Al，Fe，Mn，P等元素相对富集，S/A指数变小；（2）这两个层段测井响应表现为风化壳的特征，而且其测井曲线在纵向上具旋回特征并有连井上的可对比性；（3）不同喷发期次形成的凝灰岩结构、组分以及粒度不同。凝灰岩潜山多期风化壳（带）的存在对潜山油气藏的形成具有重要作用，成藏效应主要表现在储集层垂向分带性、风化壳油藏（晚期风化壳中）和内幕油藏（早期风化壳中）纵向叠置和复式油气聚集成藏模式等3个方面。文中对多期凝灰岩古风化壳的认识扩展了火山岩潜山的勘探深度，为火山岩潜山内幕油气勘探提供了理论依据。%Multiple episodes of volcanic eruptions lead to the development of multiple layers of weathering crust vertically in tuff buried hill. Geochemical, petrologic and logging data jointly demonstrate the existence of multiple episodes of weathering crust in the tuff buried hill. For well Ha-31, weathering crusts were developed at 1062~1080 m and 1165~1179 m and show K, Na, Ca leaching, larger CIA index, smaller S/A index, and relatively rich Al, Fe, Mn, P, etc content which are in accordance with the response to conventional well logging. Additionally, for singe well in logging, it shows some degree of cyclicity vertically, and this kind of cyclicity can be correlated among multi-wells. Moreover, tuffs originated from different eruption periods show different structures, composition, and sizes. From above, we can conclude that tuffs were formed in multiple episodes and multiple weathered crusts were developed vertically. The effects of multiple episodes of paleo-weathering crusts of tuff buried hills on hydrocarbon accumulation include vertical reservoir of zonal distribution , weathering crust reservoirs (late weathering crusts) and inner buried reservoirs (early weathering crusts) with vertical overlay, and complex hydrocarbon accumulation mode. The proposition of multiple episodes of tuff weathering crust related reservoirs extends the volcanic hill exploration depth and provides a theoretical basis for volcanic rocks inner buried hill exploration.
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