摘要
本文对四川盆地天然气的碳、氢、硫同位素组成,甲烷同系物“C_6—C_(13)”烃的正异构分布,苯、甲苯及噻吩、硫醇、二硫化碳等有机硫的展布及其地球化学进行了讨论,认为烃源岩母质类型,有机质成熟度及围岩组合等是导致天然气差异的主要原因。为天然气成因和对比研究提供了信息。
This paper is the continuation of the paper published in 1984, with the emphasis on the irregular components of natural gases from the: Sichuan Basin- the isotopic compositions of C, H and S, the normal- and isoalkane predominance (C6-C13) of CH14 homologues, and the distribution and geochemical characteristics of organic sulfur including C6H6,C7H8, RSH, CS2, etc.It is considered that natural gases from the Sichuan Baisin have different distributive characteristics in different layers and locations, suggesting that they are controlled by a combination of kerogen type, maturity of organic matter and wall-rock assemblage.1. The type of source matter (or precursor) is a main factor affecting the geochemical characteristics of natural gases. T3x-h and P2l belong to coal-series gases and Type-III source matter is dominant. The C and H isotopic compositions of natural gases are heavier, the contents of C6H6 and C7H8 are high, C7H8/C6H8 > 1, the content of C4H4S is low, and the predominance in isoalkane (C6-C13) is obvious. Jit, Piy, Z2b, etc. belong to oil-series gases and Type-I and II kerogens are dominant, indicating different geochemical characteristics of natural gases from those described above.2. The maturity of organic matter is an important factor affecting the composition of natural gases. With increasing maturity otorganic matter, the C and H isotopic compositions tend to become light. C1 and C2 isotopic values are nearly equal or even inverse, and C4H4S decreases in content.3. Wall-rock assemblage has apparent influence on the S isotopic composition. The Middle-Lower Triassic series belong to sulfate-carbonate formations enriched in gypsum. Therefore, the δ34S values of natural gases are relatively high (>20‰) against the lower values for other layers due to no gypsum layers.
出处
《地球化学》
CAS
CSCD
北大核心
1990年第1期32-43,共12页
Geochimica
