澳大利亚西北大陆架大气田的形成条件与分布特征  

Formation and Distribution of Giant Gas Fields in Northwest Shelf of Australia

作　　者：刘伟[1] 何登发[1] 王兆明[2] 高金尉[1] 

机构地区：[1]中国地质大学海相储层演化与油气富集机理教育部重点实验室,北京100083 [2]中国石油勘探开发研究院,北京100083

出　　处：《中国石油勘探》2011年第3期68-75,8,共8页China Petroleum Exploration

基　　金：中国石油天然气股份有限公司重大科技专项"全球常规油气资源评价研究"(2008E-060903)

摘　　要：被动大陆边缘的油气勘探已成为世界热点,世界各被动大陆边缘的勘探都取得了重大进展,大都以油为主,但是澳大利亚西北大陆架是世界上经典的以天然气为主导资源的含油气地区,其中天然气资源高达82%,凝析油与原油资源仅占18%。至2009年,澳大利亚西北大陆架共发现20个大气田,分布在3个盆地中。澳大利亚西北大陆架不但油气资源丰富,而且勘探开发的程度也很低,因此具有很大的研究与勘探价值。从被动大陆边缘的构造沉积演化出发,结合大气田的地质资料,分析盆地内主要的生、储、盖层特征,研究盆地内大气田的形成条件,剖析大气田分布的主控因素。研究认为,澳大利亚西北大陆架主要的烃源岩为倾向于生气的腐殖型,成熟度很高,烃源岩的特征决定了西北大陆架是一个产气区;主要的储层为同裂谷期广泛发育的海相三角洲砂岩,储集物性良好;白垩纪后稳定的被动大陆边缘沉积了一套有效的区域盖层;生、储、盖层垂向上联系紧密、局部高效组合是形成大气田的主要条件。大气田的地理分布差异明显,埃克斯茅斯台地与兰金台地区域大气田分布较为密集;大部分大气田的埋藏深度较大,储层时代主要为上三叠统与中—下侏罗统;大气田全部分布于白垩系区域盖层之下。Exploration for oil and gas in the Passive Continental Margin has been a hot spot of the whole world, and achieves a lot. The Northwest Shelf of Australia is a world-class gas province with minor oil, with 82% gas and only 18% condensate and oil, while other areas in the Margin are dominated by oil. Until 2009, 20 giant gas fields have been found in three basins in Northwest Shelf of Australia. Although the Northwest Shelf has rich hydrocarbon resources, its extent of exploration and exploitation is still low. Therefore, it is worthy of research and exploration. Based on the tectono-depositional evolution of Passive Continental Margin, combined with geological data of giant gas fields, this paper analyzes the features of main source rocks, reservoirs and seals in basins, studies the formation of giant gas fields, and thoroughly analyzes the factors controlling their distribution. It is believed that main source rock is humic and prone to generate gas, and the maturity is high, thereby the features of the source rock determine that the Northwest Shelf of is a gas province. Moreover, the main reservoirs are marine delta sandstone with excellent physical property, and they are widely developed in the syn-rift. After the Cretaceous Period, a set of excellent regional seals were deposited in the Northwest Shelf. Source rock, reservoirs, seals were vertically contacted and partially combined effectively, which is essential to the formation of giant gas fields. The geographic distribution of giant gas fields varies a lot. Most giant gas fields concentrate in Exmouth Platform and Rankin Platform. Besides, and most of them are buried deeply. The periods of reservoirs are chiefly Upper Triassic and Lower and Middle Jurassic, and all the giant gas fields are beneath the Cretaceous regional seals.

关 键 词：大气田 构造沉积演化 成藏条件 分布特点 西北大陆架 澳大利亚 

分 类 号：TE112[石油与天然气工程—油气勘探]