摘要
在准噶尔盆地二叠系中确认了一种新型的生油岩——凝灰质岩.它含有较多典型的火山碎屑沉积,致密而坚硬.有机碳含量为1—3％,干酪根类型为Ⅰ型或Ⅱ型,具有很高的产烃能力.正烷烃的主峰在C_(17)—C_(20),富含类异戊二烯烷烃、甾烷含量高于萜烷,这都是藻类有机质的特征.用干酪根热降解出生物标志物进行了油源对比.已确认它是克拉玛依油田的油源层之一.盐酸释放出的晶包有机质中的甾.萜组成也证明它是有效的生油岩.
A new type of source rock, tuffaceous rock, has been confirmed. One of main source beds for the Karamay oilfield is the Fengchengcheng group in the middle permian series. This group comprises mainly tuffacous dolomitic shales deposited in weak saline water lake. This source bed is on the peak of oil-generating, vitrinite reflectance ranges 0.8-1.1%. The kerogens occured in this group are I or II types, with high potential for oil-generating. There is also calc-tuffaceous shale source rock occurring in the east part of Junggar Basin. The solvable organic characteristics are as follows:
l.The carbon number range for the n-alkane is from C11to C32. The main peak carbon is in the range of low carbon number with odd over even preference, in the range of C15-C21, generally at C17, showing characteristice of algae and bacteria;
2.It is rich in isoprenoids with a complete series from i C12-C20;
3.The ratios of pristane to phytane are usually less than 1;
4.Most of the samples contain tetraterpans and carotanes;
5.In cycloalkanes, steranes are more than terpanes, their ratios are about 3, which show also characteristics of algae sedimentation. C29 (stigmastane) is the principal composition of steranes, next C28(ergostane) , while C27(cholestane) is the last of the three.
The correlation has been performed between the crude oils and these source rocks by biomarker compounds, which are degraded from kerogen thermo- alternating. The steranes and terpanes thermo-alternated from kerogen are close to the crude oil occurring nearby tuffaceous source rocks. The biomarker compounds released by using HCI also confirm that this new type of source rock is a efficient source of oil.
出处
《沉积学报》
CAS
CSCD
北大核心
1989年第3期3-9,共7页
Acta Sedimentologica Sinica
