柴达木盆地第四系生物气藏泥岩盖层封闭机理  

MUDSTONE CAPROCK′S SEALING MECHANISM OF BIOGENETIC GAS RESERVOIR OF QUATERNARY IN QAIDAM BASIN

作　　者：王金鹏[1] 彭仕宓[1] 管志强 姜桂凤 刘玉魁[3] 

机构地区：[1]中国石油大学资源与信息学院,北京昌平102249 [2]中国石油青海油田研究院,甘肃敦煌736202 [3]中国石油塔里木油田公司勘探事业部,新疆库尔勒841000

出　　处：《西南石油大学学报（自然科学版）》2007年第6期63-67,共5页Journal of Southwest Petroleum University(Science & Technology Edition)

摘　　要：柴达木盆地第四系生物气藏泥岩盖层处于成岩阶段早期,具有成岩性差、高孔隙度、大孔径、低突破压力的特点,造成生物气藏整体处于弱封闭状态,而大规模气田区的存在,必定有其独特的封闭机理。分析认为:第四系储盖层孔隙结构差异,为阻止或减缓生物气散失提供了最基本条件;地层饱含高矿化度地层水、滞留水充塞泥岩孔隙,加大了天然气的渗透难度;盖层同时为源岩层,可形成烃浓度封闭,阻止天然气垂向运移;盖层厚度对其封闭能力起着极为重要的补偿作用。The mudstone caprocks of biogenetic gas reservoir of Quaternary in Qaidam Basin is in the early stage of diagenesis, with the characteristics of poor consolidation, relatively high porosity, big pore diameter and relatively lower breakthrough pressure, which results in the weak sealing of biogenetic gas reservoirs. There must be special sealing mechanism to form large scale gas-bearing province. Through analysis of petrology and micro-structure characteristics of mudstone, it is indicated in this paper that the cap rock quality is the main reason that forms weak sealing state if there are sufficient gas resource and no fault destruction. In this kind of geologic condition, it can be concluded that the physical properties between mudstone and sandstone are the fundamental sealing condition to prevent and alleviate biogenetic gas loss, the mudstone saturated with underground water with high salinity and mudstone pore filled with retained water improve the difficulty of biogenetic gas permeation, the cap rock , as source rock at the same time, forms hydrocarbon density sealing to prevent biogenetic gas from migrating vertically; the compensation of cap rock thickness inhibits the biogenetic gas loss further. All of the above factors accelerate the formation of large scale biogenetic gas-bearing province.

关 键 词：第四系 生物气藏 泥岩盖层 封闭 柴达木盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]