摘要:近年来，由于全球资源量的需求增多，作为勘探程度较低的渭河盆地受到了越来越多****的关注。而制约渭河盆地油气勘探的主要矛盾是缺乏烃源岩，若盆地存在上古生界烃源岩，则具有重要油气地质意义，可为氦载体气成藏提供物质基础。为了研究渭河盆地及周缘上古生界残留地层分布特征，本文系统收集、整理了渭河盆地及周缘已有地球物理资料，结合地质、地震、钻井、地球化学等研究成果，明确了研究区上古生界残留地层分布，通过对比盆地南北缘上古生界烃源岩特征，探讨渭河盆地内部上古生界天然气勘探潜力。结果表明，渭河盆地内确实存在上古生界地层，主要位于西安凹陷和固市凹陷内，固市凹陷中煤系地层的厚度较西安凹陷大，且厚度较大处靠近南部。烃源岩产生的甲烷气通过盆地内大量的断裂运移到新生界断层封闭的圈闭构造中成藏，新生代地层中发育优质的储盖组合，新近系张家坡组上部分布大范围的湖泛沉积泥岩，构成了良好的区域性盖层，为天然气提供了有利的保存条件。此外，天然气藏的存在可为盆地内氦气成藏提供基础条件。对渭河盆地基底气源岩认识的深化，为鄂尔多斯周缘盆地群油气基础地质调查提供重要的借鉴意义。
关键词: 渭河盆地/
上古生界/
烃源岩/
油气意义
Abstract:As one of the lower exploration basins, the Weihe Basin has been widely concerned in recent years. The distribution of the Upper Paleozoic strata and the characteristics of source rocks are the key factors restricting the Paleozoic oil and gas exploration in the Weihe Basin. In order to study the residual stratigraphic distribution characteristics of Upper Paleozoic in the Weihe Basin and its surrounding area, the gravity and magnetic data of the studied area are collected and collated, and combined with the research results of seismic, geology, drilling and geochemistry, the distribution of residual strata in the Upper Paleozoic is redefined. In addition, the exploration potential of the Upper Paleozoic in the Weihe Basin is discussed by comparing the characteristics of source rocks along the northern and southern margin of the basin. The results show that the existence of Upper Paleozoic in Weihe Basin, mainly located in the Xi’an sag and Gushi depression, and the thickness of the coal strata in the Gushi depression is larger than the former, especially in the south. The methane gas that produced by the source rocks was transported through a large number of fractures in the basin to the traps structure of the Cenozoic fault, and the high quality reservoirs were developed in the Cenozoic strata, especially in the upper part of the Neogene Zhangjiapo Formation .The lake deposition can form a good regional cap rock that provide favorable preservation conditions for natural gas. In addition, the existence of natural gas reservoirs can provide the basic conditions for helium accumulation in the basin. The deepening understanding of the basement gas source rocks in the Weihe Basin can provide important reference for the geological survey of the oil and gas in the Ordos Basin.
Key words:Weihe Basin/
Upper Paleozoic/
Source rocks/
Hydrocarbon significance
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