摘要
大庆长垣南部浅层气主要为来源于嫩江组一二段的生物气,混入少量的青山口组热成因气和无机成因的CO2.明水组沉积末期为嫩江组一二段大量生排生物气时期,此时断裂活动导致黑帝庙油层背斜和断圈的形成,并诱导生物气垂向运移,"三期复合"使大量生物气向黑帝庙油层运移.活动断层均为"断裂密集带"的边界断层,沿其垂向运移的生物气聚集的部位取决于断层与两盘地层的配置关系,与断层倾向相反的一盘是生物气聚集的主要部位,大庆长垣南部总体为"西缓东陡"的不对称背斜,生物气主要富集在断裂密集带东部边界的圈闭中.黑帝庙油层纵向上分为5套储盖组合,下部3套组合盖层厚度较大,受断层错断的概率较小,是主要的目的层.黑帝庙油层大部分圈闭为"断圈",断层侧向封闭性决定圈闭的潜力,断层侧向封闭所需SGR低限为0.375,利用Allan图解标定断层侧向封闭性并分析圈闭的潜力,与不考虑断层侧向封闭性时圈闭有3种变化:一是断层侧向封闭,面积和幅度没有改变的圈闭(Ⅰ型);二是断层侧向封闭具有分段性,面积和幅度变小的圈闭(Ⅱ型);三是断层侧向不封闭,不存在的圈闭(Ⅲ型).其中Ⅰ和Ⅱ型圈闭是生物气聚集的有利目标.从大庆长垣南部看松辽盆地浅层气成藏关键因素是有沟通气源的断层控制的圈闭的完整性(背斜或断层侧向封闭性较好的断圈)和区域稳定分布的盖层.
Shallow gas in the south of Daqing placanticline is mainly biogas originated from K1n1＋2,mixed with a small amount of thermogenic gas of K1qn and inorganic CO2. The main biogas generation and expulsion period of K1n1＋2 is the end of K2m sedimentary period,when fault activities caused the formation of anticline and fault trap of Heidimiao oil layer and induced vertical migration of biogas. The composite of the three periods made large amount of biogas migrate into Heidimiao oil layer. Active faults are all boundary faults in fault-condensed belt,along which biogas migrated vertically. The position of biogas accumulation depends on allocation relation between fault and strata of two walls. The wall whose dip is contrary to that of the fault is the main position for biogas accumulation. Generally the southern part of Daqing placanticline is an asymmetric anticline that is gentle in the west and steep in the east. Biogas is mainly accumulated in the traps of the east boundary of fault-condensed belt. There are 5 sets of reservoir-seal assemblages. Cap rock thicknesses of 3 sets of assemblages in the lower part are greater and the probabilities of them to be leaped by faults are relatively small. They are the main target beds. Most of the traps in Heidimiao oil layer are fault traps. The lateral sealing of fault determines trapping potential. The lower limit of SGR required by lateral seal of fault is 0.375. There are 3 kinds of situations when we analyze trapping potential by use of Allen graphic to calibrate lateral sealing of fault or not taking lateral sealing of fault into consideration. The first is that fault is sealing in the lateral and the area and amplitude of trap don＇t change （type Ⅰ）. The second is that the lateral sealing of fault is sectionalized and the area and amplitude of trap become smaller （type Ⅱ）. The third is that fault isn＇t sealing in the lateral and there is no trap （type Ⅲ）. Among them,traps of Ⅰand Ⅱare favorable targets for biogas accumulation. The south of
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2011年第1期93-102,共10页
Earth Science-Journal of China University of Geosciences
基金
国家自然科学基金项目(No.41072163)
关键词
长垣南部
浅层气
断裂
圈闭
通道
保存
石油地质
the south of placanticline
shallow gas
fault
trap
pathway
preservation
petroleum geology.
