柴达木盆地七个泉组和第四系-新近系的分界  

Qigequan Formation and Quaternary-Neogene boundary in Qaidam basin

作　　者：孙镇城[1] 乔子真[2] 景明昌[1] 张海泉[2] 孙乃达[1] 路艳丽[2] 王洪江[1] 

机构地区：[1]中国石油大学,北京102200 [2]中国石油天然气股份有限公司青海油田分公司石油勘探开发研究院,甘肃敦煌736202

出　　处：《石油与天然气地质》2006年第3期422-432,共11页Oil & Gas Geology

基　　金：中国石油天然气集团公司"九五"油气勘探科技工程项目(970208-01-01)

摘　　要：柴达木盆地东南部三湖坳陷,已发现3个上新统-第四系七个泉组气源岩的气田。把三湖坳陷七个泉组底界当成第四系与新近系的分界是一个误解。基于测井、地震地层和磁性生物地层的研究,三湖坳陷七个泉组底的年龄为2.80M a,位于涩北新深1井1 747 m。柴达木盆地第四系与新近系分界,在许多论文中,有3种不同观点:①奥杜威末,1.67M a(1.80 M a),位于涩中6井710 m,即测井标准层K3以上19 m;②松山与高斯分界,2.48 M a(2.60 M a),位于涩深1井1 460 m,即K10以下37 m;③马默思末,3.05 M a,位于达参1井2 779 m。上述3个分界数据中无一与七个泉组底界对应。距今约1.80 M a的第四系与新近系分界定义已被国际地层委员会1998年投票通过,并于1999年经国际地科联批准。因此,依此定义来看,三湖坳陷大部分气源岩是晚新近纪-早第四纪的沉积,尤其是晚新近纪上新世。在柴达木盆地油气勘探开发研究中,作者建议最好使用地层单位名称七个泉组,而不用符号Q1+2。连接地震反射T0界面(测井标准层K13)和盆地边缘有局部不整合的七个泉组底界的对比,对于研究构造运动、成气和成藏是很有用的。作为七个泉组底界,地震反射界面T0的对比,在柴达木盆地三湖坳陷中央具有实用性、等时性和可操作性等特点。Three gas fields sourced from Pliocene-Quaternary Qigequan Formation have been found in Sanhu depression in southeastern Qaidam basin. It is a misunderstanding to take the base of Qigequan Formation in Sanhu depression as the boundary of Quaternary and Neogene. Based on logging, seismic stratigraphic and magnetobiostratigraphic studies, the age of the base of Qigequan Formation in Sanhu depression is believed to be 2.80 Ma, it is at a depth of 1 747 m in Xinshen 1 well drilled in Sebei area. There are three different opinions on the Quaternary-Neogene boundary in Qaidam basin in literatures. （1）The end of Olduvai, 1.67 Ma, （ 1.80 Ma） ; it is at a depth of 710 m in Sezhong 6 well, i. e. 19 m above the log-marker K3. （2）The boundary of Matsuyama and Gauss, 2.48 Ma（2.60 Ma） ; it is at a depth of 1 460 m deep in Seshen 1 well, i.e. 37 m below the logmarker K10. （3）The end of Mammoth,3.05 Ma; it is 2 779 m deep in Dacan 1 well. None of the above three boundaries correlates with the base of Qigequan Formation. The definition of Quaternary-Neogene boundary, with an age of 1.80 Ma, has been adopted by the International Commission on Stratigraphy （ICS） through voting in 1998, and accepted by the International Union of Geological Sciences （IUGS） in 1999. According to this definition, most of the gas source rocks in Sanhu depression were deposited during Late Neogene to Early Quaternary, especially in Pliocene. It is suggested in this paper that the stratigra-phic unit name of Qigequan Formation rather than the symbol ＂Q1＋2＂ should be used in petroleum exploration and development research in Qaidam basin. Correlation of the seismic reflector TO （ log-marker K13 ） and the base of Qigequan Formation with local unconformities at the edge of the basin is very useful for study of tectonic movement, gas generation and reservoiring. As the base of Qigequan Formation, the correlation of seismic reflector TO is characterized by practicability, isochroneity and operability in central Sanhu depres

关 键 词：磁性生物地层 地震反射界面 不整合 第四纪 柴达木盆地 

分 类 号：TE111.3[石油与天然气工程—油气勘探]