新特提斯构造域陆缘深水富气盆地群分布及其天然气地质特征

    Distribution and geological characteristics of natural gas in the continental margin deepwater of the Neotethys tectonic domain

    • 摘要: 深水区是全球油气勘探的前缘领域,新特提斯构造域大陆边缘深水盆地群是全球重要的富气区,由于勘探程度较浅,成藏主控因素尚不明确,制约了该区域深水油气资源勘探。立足研究区构造、地层等基础地质资料、深水油气勘探开发进展与气田最新资料,综合分析深水区富气盆地分布和天然气成藏地质条件,探讨该区域深水天然气勘探存在的领域。结果表明:新特提斯构造域陆缘深水盆地群划分为东、中、西3段,深水区主力气源岩以煤系地层,次要为海相泥岩。主力储层为海相浊积砂岩,来源于三角洲和浊积扇。主力区域性盖层为新近系和下白垩统厚层海相泥岩,东地中海海域墨西拿阶盐岩是重要区域性盖层。圈闭以构造圈闭为主。受新特提斯洋自东向西逐渐闭合构造演化的控制,油气成藏组合在东段澳大利亚西北陆架主要为裂谷期生储被动陆缘期盖成藏组合,在西段东地中海区域主要为裂谷期生被动陆缘期储盖成藏组合,在中段陆缘深水盆地中上述两种成藏组合类型兼而有之。受新特提斯构造域深水区油气勘探程度、已有油气发现和油气地质条件等影响,新特提斯构造域陆缘深水区存在成熟区、半成熟区和新区三大勘探领域。

       

      Abstract: Deepwater basins in the continental margin of the Neotethys tectonic domain are one of the important gas rich regions in the world. However, the exploration degree of deepwater oil and gas in the region is relatively low, and the main controlling factors for reservoir formation are unclear, which restricted the exploration of deepwater oil-gas resources in this region. Based on the basic geological data such as structure and stratum, progresses in deepwater gas exploration and exploitation, and the latest data of gas fields in the study area, we comprehensively analyzed the distribution of gas-ich basins and geological conditions for gas reservoir generation in deep water areas, and discussed the frontier of deepwater natural gas exploration in this region. Results show that the deepwater basins in continental margin of the Neotethys tectonic domain can be divided into three segments: east, middle, and west. The gas source rocks in the deep water area are mainly coal-bearing strata, followed by marine mudstone. The reservoirs are mainly composed of clastic rocks such as shallow marine deltaic sandstone and deep-sea turbidite sandstone. The caprocks are mainly composed of the Lower Cretaceous marine shale and Miocene-Pliocene marine mudstone. Traps are mainly structural traps. With the gradual closing-up of the Neotethys Ocean from east to west, in the Northwest Australian Shelf of the eastern segment, oil and gas are generated-stored in rifting stage and capped in passive continental margin stage, while in the Eastern Mediterranean region of the western segment, oil and gas are generated in rifting stage and stored-capped in passive continental margin stage. For those in the middle segment including the eastern and western continental margins of India, the scenarios are in-between. Controlled by the degree of oil and gas exploration in the deep-water area of the Neotethys tectonic domain, existing oil and gas discoveries, and oil and gas geological conditions, there are three major exploration zones in the continental margin deepwater area of the Neotethys tectonic domain: mature zone, semi-mature zone, and new zone.

       

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