四川盆地侏罗系—震旦系天然气的地球化学特征

文章通过对四川盆地震旦系—侏罗系含气层系中天然气的烃类组成、非烃组成及碳氢同位素组成资料的分析,探讨了天然气的成因类型、成熟度、运移和混合作用等。四川盆地天然气的组成特征不仅受母质类型的影响,而且受成熟度的影响。根据碳氢同位素组成,可以将四川盆地的天然气划分为侏罗系“浅层”油伴生腐泥型气、上三叠统热成因腐殖型气及中三叠统—震旦系“深层”油裂解腐泥型气等三大类型。根据分析资料推断,川西侏罗系、川东卧龙河上三叠统及石炭系的天然气为运移次生成因。三叠系嘉陵江组、二叠系和石炭系的天然气普遍具有同位素倒转现象,认为这是由于天然气混合作用的结果。

GEO CHEMICAL CHARACTERISTICS OF JURASSIC-SINIAN GAS IN SICHUAN BASIN

Through analysing the composition data of hydrocarbon, nonhydrocarbon, carbon isotope and hydrogen isotope of the gas in Jurassic-Sinian gas-bearing strata in Sichuan Basin, the genetic types,maturity,migration,hybridization etc. of the gas are discussed. The composition characteristics of the gas in Sichuan Basin are not only influenced by matrix materials but also by maturity. In the light of carbon-hydrogen isotope compositions, the gas can be divided into three types, ie, the sapropel one developed from Jurassic"shallow" oil source body, the thermogenic humic one of Upper Triassic and the sapropel one decomposed from the oil of Middle Triassic-Sinian "deep"strata. Wang Shi-qian,senior engineer, graduated in petroleum geology from Wuhan Geological Institute; Now he is engaged in the researches and translations of petroleum geology and organic geochemistry. Add: According to the datum analysis, the gases of Jurassic in West Sichuan, Wolonghe Upper Triassic and Carboniferous in East Sichuan belong to migration secondary one. The gas of Triassic Jialingjiang formation, Permian and Carboniferous is generally of isotope reversal phenomenon,which is caused by gas hybridization.