波斯湾盆地大气田的形成条件与分布规律  

Formation and Distribution of Giant Gas Fields in Persian Gulf Basin

作　　者：贾小乐[1] 何登发[1] 童晓光 王兆明[3] 

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]中国石油天然气勘探开发公司,北京100034 [3]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8-22,6,共15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：以波斯湾盆地已发现的54个大气田数据为基础,应用含油气系统的概念和分析方法,对大气田逐个进行解剖,探讨了波斯湾盆地大气田的形成条件与分布规律。研究表明,波斯湾盆地大气田的气源主要为志留系Gahkum组和Qusaiba热页岩段及白垩系的Kazhdumi组,主要储集于二叠系、侏罗系和白垩系中,受下三叠统Sudair组致密灰岩区域盖层、上侏罗统提塘阶Hith组硬石膏盖层和下—中新统下Fars组(Gachasaran组)蒸发岩系等封盖,在构造圈闭的环境下聚集成藏。区域上大气田主要分布于两个大区:前陆带和被动大陆边缘区,不同地区天然气富集的层系不同。天然气的分布主要受4个因素的控制,即烃源岩的有机质类型与热演化,储层有利的储集条件,优质的区域和直接盖层,以及侧向挤压、盐流动、基底断裂等构造因素。这些因素控制了天然气的分布区域和天然气聚集的层位。预测有利勘探区为:一是"老区"的构造型勘探目标;二是"老区"的非构造型勘探目标;三是"新区"的勘探目标。Based on the data of 54 giant gas fields discovered in the Persian Gulf Basin, this paper applies the concept and analytic method of petroleum system, dissects giant gas fields one by one, and probes into their formation and distribution in the Basin. Study shows that the source rocks of giant gas fields are Silurian Gahkum Formation, Qusaiba Shale Member, and Cretaceous Kazhdumi Formation. The reservoirs are mainly in Permian, Jurassic and Cretaceous strata. Giant gas fields are controlled by the tight limestone regional cap rocks in Lower Triassic Sudair Formation, the anhydrite seal in Upper Jurassic Tithonian Hith Formation, and the evaporite rock seal in Lower Miocene Fars Formation (Gachasaran Formation). The main trap is structural. In this region giant gas fields are mainly distributed in two regions: foreland area and passive continental margin, and gas is rich in different layers and formations in different regions. Gas distribution is mainly controlled by four factors: organic material type and gradation of thermal evolution of source rocks, accumulation conditions favorable for reservoirs, high-quality regional and local cap rocks, and structural elements like lateral compression, salt flow, and basement rift. They determine the distribution region and the accumulation zone of gas. It is predicted that there are three favorable exploration areas: the first is the 'areas that have been explored and developed' and the exploration targets in these areas are structural; the second is the 'areas that have been explored and developed' and the exploration targets here are nonstructural; the third is the 'areas that have not been explored and developed'.

关 键 词：大气田 含油气系统 形成条件 分布特征 波斯湾盆地 

分 类 号：TE112[石油与天然气工程—油气勘探]