Carbon isotope characteristics,origin and distribution of the natural gases from the Tertiary salty lacustrine facies in the West Depression Region in the Qaidam Basin  

作　　者：张晓宝 胡勇 马立元 孟自芳 段毅 周世新 彭德华 

机构地区：[1]State Key Laboratory of Gas Geochemistry, Lanzhou Institute of Geology, Chinese Academy of Sciences [2]Research Institute of Petroleum Exploration and Development, Qinghai Petroleum Company, CNPC

出　　处：《Science China Earth Sciences》2003年第7期694-707,共14页中国科学（地球科学英文版）

基　　金：This work was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX2-111);the National Natural Science Foundation of China(Grant Nos.49972051 and 40172053).

摘　　要：The Tertiary in the West Depression Region of the Qaidam Basin has the typical inland salty lacustrine deposits in China. 34 natural gas samples were collected from 13 oil fields in the West Depression Region in the basin, the chemical compositions and carbon isotopes of methane, ethane, propane, and butane were measured. According to the carbon isotope characteristics of natural gases in combination with geochemical characteristics of the source rocks and crude oils, the natural gases can be divided into sapropelic associated gas, mixed organic matter-derived associated gas, coal-derived gas and mixed gas. The carbon isotope characteristics, origin and distribution of the natural gases are considered to be related with the types and distribution of organic inputs in lake environments with different salinities. The lake salinity can regionally forecast the distribution of the different genetic types of natural gas. Compared with the different genetic types of natural gas from other Chinese basins, the carbon isotopes of the heavy hydrocarbons of the natural gas from the Tertiary salt lacustrine facies in the Qaidam Basin are extremely heavier. Therefore, this should be considered when natural gases are genetically classified in the basin.The Tertiary in the West Depression Region of the Qaidam Basin has the typical inland salty lacustrine deposits in China. 34 natural gas samples were collected from 13 oil fields in the West Depression Region in the basin, the chemical compositions and carbon isotopes of methane, ethane, propane, and butane were measured. According to the carbon isotope characteristics of natural gases in combination with geochemical characteristics of the source rocks and crude oils, the natural gases can be divided into sapropelic associated gas, mixed organic matter-derived associated gas, coal-derived gas and mixed gas. The carbon isotope characteristics, origin and distribution of the natural gases are considered to be related with the types and distribution of organic inputs in lake environments with different salinities. The lake salinity can regionally forecast the distribution of the different genetic types of natural gas. Compared with the different genetic types of natural gas from other Chinese basins, the carbon isotopes of the heavy hydrocarbons of the natural gas from the Tertiary salt lacustrine facies in the Qaidam Basin are extremely heavier. Therefore, this should be considered when natural gases are genetically classified in the basin.

关 键 词：salt lacustrine  NATURAL GAS carbon isotope  genetic type  NATURAL GAS forecast  Qaidam Basin. 

分 类 号：P595[天文地球—地球化学]