柴达木盆地第四系生物成因气质疑  

Queries about biogenesis of Quaternary gas in Qaidam Basin,NW China

作　　者：马龙[1] 陈洪德[1] 张景廉[2] 石兰亭[2] 卫平生[2] 

机构地区：[1]成都理工大学沉积学院 [2]中国石油勘探开发研究院西北分院

出　　处：《石油勘探与开发》2008年第2期250-256,共7页Petroleum Exploration and Development

摘　　要：柴达木盆地东部三湖地区第四系泥岩有机质丰度低、厚度小,且乙酸含量低,其有机地球化学特征不利于天然气的生成。以7个实例证实,碳同位素判据无法确认一些天然气的成因。以5个实验结果证实,费-托合成反应同样可产生碳同位素分馏效应,对于区分生物成因气与非生物成因气,碳同位素不是可靠的判据。过柴达木盆地的2条地学断面和大地电磁测深证实,柴达木盆地深部上地幔上隆,并有3条超壳深大断裂,中地壳内有低速-高导层,富含CO2(或CO)及H2,又有金属催化元素,在中地壳恰当的温度、压力条件下,可发生费-托反应合成烃类。因此,柴达木盆地第四系下部可能有非生物成因天然气,天然气勘探前景将更好。Organic geochemistry of Quaternary source rocks is not favorable to the generation of natural gas, such as the low organic matter content, the thin layer and the low ethanoic acid content in mudstones. Seven cases of natural gas occurrences show that the gas genesis can not be recognized by the current carbon isotope compositions. Five simulation experiments show that carbon isotopic fractionation can also happen in the Fischer-Tropsch reaction. Carbon isotope is not a reliable criterion for distinguishing biogenic from abiogenic gases. Based on 2 geo-transects and electromagnetic soundings, there is an uplifting upper mantle and 3 ultra-deep faults in the deeper crust, and there is a low velocity - high conductive layer in the mid-crust which is rich in CO2 （CO） and H2. If metal catalytic elements participated, the Fischer- Tropsch reaction might happen and formed hydrocarbons under certain temperatures and pressures. The deep crust structure shows that abiogenic gas might exist under the Quaternary System in the Qaidam Basin.

关 键 词：生物成因气 碳同位素 分馏作用 费-托反应 第四系 柴迭木盆地 

分 类 号：TE122.11[石油与天然气工程—油气勘探]