我国80年代气体地球化学研究

A Review of Researches on Gas Geochemistry in China's 80s

本文综述了近十年我国气体地球化学研究的成果。天然气地球化学是其中最主要的领域,在成因类型及综合判识、气源对比方面取得了较大成就。其中煤型气综合判识、生物—热催化过渡带的理论有重要学术和实践意义。稀有和非烃气体研究也有较快进展。沉积壳层幔源氦工业储集的发现属世界前例。腾冲地热区深源甲烷的探讨、大气CO_2浓度及碳、氧同位素研究、煤矿CO_2突出及其成因、地震灾害预防预报的气体地球化学研究等都进行了有益的探索。

Gas geochemistry is a subject that deals with the formation, migration, reservation and distribution of gaseous elements and compounds in natural gas. Among the natural gases, hydrocarbons are a kind of important normal energy resource and chemical industrial material, non-hydrocharbons such as CO2 and H2S and helium of rare gases are also important natural resources. As the gas geochemical research can porvide valuable masseages for the exploration of these gases, so this subject developed rapidly in the past 20 years. Geochemical study of natural gases had made a great achivement in abroad, and it has been a mature subject. In the present paper, a brief review of gas geochemical study of Chinese 1980s is provided. In the aspect of gaseous hydrocarbon, a great outcome had been made in the synthetical identification of coal associated gas, which consisting of about ten idices such as carbon and hydrogen isotopes of methane, Ar isotopes, abundant of helium and mercury, indices of benzo, etc. and this method is in the lead position all over the world. As for the sorthing of origin types of natural gases, a sorting system is established which combined the characters of natural gas and the geologic background of China, especially the proposed theory of thermocatalistic transitional gas played an important role in the theory of gas formation and the exploration of shallow reserved gas. In the study of carbon and hydrogen isotopes, a mathmatical model is established based on the sedimentry basin. And in the research of light hydrocarbon, more information is provided, and a gas-liquid-solid state serieal constructing method is established. The researches on non-hydrocarbons and rare gas progressed greatly. The discovery of mantle derived helium in sedimentary layer come the first in the world list, wherea the concentration of helium reaches to 0.1-1.3%, and the mantle derived helium possesses 30-60%. Satisfactory progress had been made in the field of environment a.nd disaster reduction by using of gas geochemistry, CO2 concentration and the variation of carbon isotope of 5 regions in northwestern China are studied, The cause of CO2 outburst in coal field, the change of chemical and isotopic composition of hot spring gas before and after earthquake are also studied. Character of hot spring gas in Tengchong district and the geologic bakcground are analysed, the result indicates that the methane in hot spring probably be derived from mantle, the volcano in the area is a dormant volcao, and it still has the possiblity of re-explosion.