辽东湾凝析气田超压成因及侧向传递机制初探  

A preliminary study on origin and transmissive mechanisms of overpressure in the JZ20-2 Condensate Field in the Liaodong Bay

作　　者：李潍莲[1] 刘震[1] 夏庆龙[2] 周心怀[2] 

机构地区：[1]中国石油大学石油天然气成藏机理教育部重点实验室,北京102249 [2]中国海洋石油总公司天津分公司,天津300452

出　　处：《地质科学》2008年第2期377-388,共12页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：“十五”国家重大科技攻关项目“中国大中型油田勘探开发关键技术研究”(编号:SC04TJ-TQL-001)的部分成果

摘　　要：位于辽东湾西部低凸起北端的JZ20-2超压凝析气田,离供烃中心较远,压力系数却达到1.56～1.7,这在我国东部裂谷盆地比较少见。经过综合分析,作者认为JZ20-2凝析气田异常高压的形成与其所处的特殊地质背景紧密相关,辽中凹陷沙河街组三段超压凝析油气沿不整合面、砂体输导通道向辽东湾西部低凸起的运移、充注和能量的侧向传递是JZ20-2凝析气田异常高压形成的根本原因,而上覆东营组二段下亚段-东营组三段巨厚的强超压泥岩封盖和辽西3号边界断层侧向遮挡共同构成的优越封闭环境是超压保存的必要条件。本文分析了该气田超压特征及其远距离超压侧向传递的成因机制,不仅有助于揭示辽东湾西部低凸起超压流体运移聚集的规律和成藏作用,而且可能提供了一个超压远距离侧向传递的典型实例。Located in the northern part of the West Lower Uplift of Liaodong Bay, the JZ20-2 overpressured condensate field was far from the hydrocarbon-generating center. Its pressure coefficient was as high as 1.56 - 1.70. This phenomenon was rare in the Cenozoic rift basins in East China. Based on comprehensive analyses, it was concluded that the formation of JZ20-2 reservoir overpressure was closely related to its special regional geological conditions. The primary reasons resulting in the overpressure of the field were the migration and charge of the overpressured condensates of the 3rd Member, Shahejie Formation from the Liaozhong Sag to the West Lower Uplift of Liaodong Bay along unconformities and pathways in sand bodies, and lateral transmission of overpressure caused by these factors. The favorable seal conditions, which included the super-thick and high pressure mudstone cap rocks of the 2nd and 3rd Members, Dongying Formation and the favorable block capability of the Liaoxi No. 3 fault, were prerequisite to conservation of the overpressure of the field. The study on the reservoir overpressure characteristics and its transmissive mechanisms in the JZ20-2 Condensate Field was not only beneficial to understand the migration and accumulation of overpressured hydrocarbon in the West Lower Uplift of Liaodong Bay, but also possibly provided a typical example of overpressure transmission through long lateral distance.

关 键 词：JZ20-2凝析气田 超压成因 超压传递 辽东湾西部低凸起 

分 类 号：TE122[石油与天然气工程—油气勘探]