【作者】 于腾飞；

【导师】 林玉祥；

【作者基本信息】 山东科技大学 ， 矿产普查与勘探， 2011， 硕士

【摘要】 沁水盆地煤系地层游离气资源丰富,主要赋存在煤层顶底板和煤系地层常规储层中。开展游离气成藏机制与模式研究,对本区游离气勘探具有重要意义。本文研究了沁水盆地演化过程,划分出4个演化阶段,其中燕山期为主要的游离气成藏期；明确了五套主要的生、储、盖组合,其中最主要的生储盖组合为山西组自生自储组合和太原组自生自储组合。通过游离气成藏要素和成藏主控因素分析,总结了游离气的分布规律：(1)构造高部位有利于游离气的聚集；(2)煤层含气量越高,顶底板储层含气量也越高；(3)煤层顶板及上覆盖层的封闭性决定了游离气聚集的层位,优质盖层之下的储层易于成藏。本文提出了天然气“多源多相、动态转化、定向聚散”的成藏机理。本区天然气来源于煤岩、暗色泥岩、暗色碳酸盐岩等多种类型母岩,赋存状态多样,谓之“多源多相”；在印支期以来的多期构造运动中,不同赋存状态的天然气既有自己独特的演化历程,其间也存在相互交换,即“动态转化”；而“定向聚散”则强调了本区煤系地层天然气成藏过程的不可逆性。按游离气藏成藏过程及其后生演化建立了本区游离气成藏模式,将沁水盆地游离气藏分为原生型、调整型和改造型等3种,其中改造型又可进一步划分为原生改造型和调整改造型2种。采用煤层含气量+储层物性+盖层封闭性的思路进行游离气远景评价,得出盆地中央带为有利区(Ⅰ区)、盆地边部为较有利区(Ⅱ区)。更多还原

【Abstract】 Coal strata in Qinshui Basin are rich in natural gas resources, and free gas mainly exists in the roof and floor of coal-bed and in the conventional reservoirs of coal seam formation in the. The study of free gas accumulation mechanism and accumulation model has great meaning in exploring free gas in Qinshui Basin.This paper make a definite concept of four process stages of the revolution of the coal strata in Qinshui Basin by comprehensive study which including Yanshanian-major natural gas accumulation stages of development. In Yanshanian, there are five sets of main source-reservoir-cap assemblage, and the self-generating and self-preserving reservoirs of Shanxi formation and Taiyuan formation are tow main sets.Through the analysis of the accumulation elements and the main controlling factors of free gas, the paper summarizes the rule of the distribution of free gas:(1) structures of high position are favorable to the accumulation of free gas; (2) the coal bed methane content of the roof and floor of coal seam is higher as the gas content of the coal seam is higher; (3) the closeness of the roof of coal seam and covering layer decides the horizon of the gathering of free gas, the good sealing condition is good for accumulation.The conclusion is the accumulation mechanism, including multi-source and multi-phase state, dynamic transformation, unidirectionally accumulate and escape. Natural gas of coal measure strata in this area comes from many kinds of source rocks, such as coal, dark mudstone and dark carbonate rock, and exists in many states. So we call that“multi-source and multi-phase state”. Since Indo-Chinese period, different phasestates of natural gas have different processes of transformation, and they’re interconvertible. That is so-called“dynamic transformation”, while the "unidirectionally accumulate and escape" emphasizes the irreversibility of the process of accumulation.In this paper, I set up the accumulation model according to the accumulation process and secondary evolution of free gas, and free gas reservoir of Qinshui Basin could be classified into three types:native, adjustment and transformation. And the adjusted gas reservoir could be further divided into native-transformation type and adjusted-transformation type.By evaluating free gas prospect synthetically based on the overall consideration of the content of coal seam gas, properties of reservoir and closeness of seal, the most favorable gas-bearing zones located in the central belt of the basin (I zone) and the relatively favorable gas-bearing zones located in the edge of the basin (II zone) are recognized.更多还原