摘要
鄂尔多斯盆地东南部上古生界天然气储层主要为太原组、山西组、下石盒子组和上石盒子组,岩性以石英砂岩为主。储层的主要成岩作用有压实和压溶作用、胶结和交代作用、裂隙和溶蚀作用等,依据显微镜下岩相学研究,在研究区可以识别出四个大的成岩阶段,分别对应早成岩阶段的早期和晚期、晚成岩阶段的早期和晚期。识别出两期天然气包裹体,第一期天然气包裹体形成于早成岩阶段的晚期,分布在早期裂隙及与其相关的溶蚀孔隙中,形态不规则,气/液比较高,偶尔可见包裹体发荧光。第二期天然气包裹体形成于晚成岩阶段晚期,分布在晚期裂隙中和晚期亮晶方解石和石英胶结物中,包裹体气/液比小,大部分为有机气态和盐水组成的气液两相有机包裹体,包裹体壁薄色浅。研究认为第一期代表了早期天然气初次运移和注入储层事件,而第二期代表了天然气大规模二次运移聚集成藏事件。
In the southeast of the Ordos Basin,the Upper Paleozoic gas reservoir maily includes Taiyuan Formation,Shanxi Formation,the lower Shihezi Formation and the upper Shihezi Formation and lithology is mainly quartz sandstone.Based on microscope petrographic study,the main diagenetic types of the reservoir are compaction,pressure dissolution,cementation and metasomatism,fracture and dissolution,and four major diagenetic stages can be identified in study reservoir.The first stage is precocious rock early stage and shallow burial diagenesis,whose performances are that the clastic particles present a point-line contact relation and a large number of siliceous cement forms.The second stage is fracture and dissolution,which is the strongest diagenesis in this area and quartz and feldspar are generally affected then a great many crack forms,meanwhile a lot of pores appear.The third stage is the late deep burial diagenesis,whose performances are that the quartz clastic particle dissolves and early crack forms then the recrystallization happens,making the dissolution pore and fracture heal,and multiple growing increased edges form as well as a lot of siliceous cement.The fourth stage is the formation of late tectonic stress fracture,late carbonate and gypsum mineral salts.Two phases of gas inclusions are identified.The first phase of gas inclusions was formed in the late stage of early diagenesis.This period of inclusion hasa higher gas/liquid,which is generally about 20 percent,and fluoresce inclusions are seen.The formation temperatures of inclusions are between 130℃ and 140℃ and the salinity is between 1.0 wt %.and 2.0 wt%.The second phase of the natural gas inclusions forming in late diagenetic later period are distributed in late fractures and the late sparry calcite and quartz cement.The organic inclusions in later sparry calcite and quartz cement are more,and the planar distribution,distributed in calcite or plagioclase cleavage plane,which are maily gaseous hydrocarbon inclusions.This inclusion＇s gas/liquid ratio is small,generally less than 10% while most of them are the organic gaseous and brine forming the gas and liquid these two phase inclusion with the parcel body wall is thin and the color is shallow.Inclusion＇s formation temperature is between 160℃ and 170℃ and its salinities are between 3.0 wt % and 4.0 wt %.Studies suggest that the first stage represents the early gas＇s primary migration and reservoir injection events,while the second stage represents the natural gas＇s massive secondary migration and gas accumulation event.
出处
《沉积学报》
CAS
CSCD
北大核心
2013年第4期693-698,共6页
Acta Sedimentologica Sinica
基金
中国地质调查局<鄂尔多斯盆地与周缘构造盆地关系研究>(编号:1212011121095)
西北基础地质调查成果集成与综合研究(编号:1212011220649)资助
关键词
鄂尔多斯盆地
包裹体
上古生界
成藏期次
Ordos basin
inclusion
Upper Paleozoic
hydrocarbon accumulation time
