多元天然气成因判识新指标及图版

摘要

为解决深层—超深层和非常规领域天然气勘探中面临的高演化、多元天然气成因和来源判识等关键性技术难题,通过实验新技术以及地质资料综合分析,完善了多元天然气成因判识方法体系.建立了腐泥型有机质不同演化阶段干酪根降解气和原油裂解气、聚集和分散型液态烃裂解气,N2、CO2有机和无机成因,惰性气体壳源和幔源成因,He、N2、CO2、天然气汞含量判识煤成气和油型气等多元天然气成因判识新指标及图版.通过在主要含气盆地的应用,明确了四川、塔里木和松辽盆地复杂气藏天然气成因和来源,有效支持四川盆地震旦系—寒武系古老碳酸盐岩、塔里木盆地库车坳陷深层、松辽盆地深层火山岩等领域的天然气勘探.%Identification of natural gas genesis and source for high-matured multiple natural gases is a great challenge in the exploration of deep-ultra deep and unconventional natural gases.In this paper,the genesis identification method system of multiple natural gases is enriched through new experimental techniques and comprehensive analysis of geological data.New indexes and charts of genesis identification for multiple natural gases were determined to distinguish the sapropelic kerogen degraded gas and crude oil cracking gas,accumulated and scattered liquid hydrocarbon cracking gas in different evolution stages,nitrogen,carbon dioxide of organic and inorganic origins,inert gases of crustal and mantled origins,coal-formed gas and oil-type gas by helium,nitrogen,carbon dioxide and mercury content in natural gas.These indexes and charts have been successfully applied in the Sichuan,Tarim and Songliao basins to identify the natural gas genesis and source for complicated gas reservoirs.The research results have provided effective support for the natural gas exploration in the Sinian-Cambrian ancient carbonate formations in the Sichuan Basin,deep formations in the Kuqa depression of the Tarim Basin,and deep volcanic formations in the Songliao Basin.