煤成大、中型气田天然气的碳同位素特征

本文根据我国典型大、中型气田的283组碳同位素数据,通过煤成气与油型气的对比,探讨了我国大、中型煤成气田烷烃气的基本特征。研究结果表明,烷烃气碳同位素具有以下特征:甲烷及其同系物随碳分子数的增加,δ13C频率区间值展布缩小,主频率值变重;④煤成气与油型气相比,具有低的δ13C₁ 主频率峰值,高的δ13C₂值;㈣Δ(δ13C₂-δ13C₁)与δ13C₁ 呈负相关关系;煤成气碳同位素系列只有两种形式,即正碳同位素系列和同位素倒转系列;5烷烃气碳同位素系列特征取决于显微组分、演化程度和成藏机制。 

CARBON ISOTOPIC CHARACTERISTICS OF NATURAL GAS IN THE GREAT-MEDIUM COAL-FORMED GAS FIELDS OF CHINA

Based on 283 sets of carbon isotopic data from typical great-medium gas fields in China,the elementary characteristics of gas alkyl hydrocarbon in the great-medium coal formed gas fields of China are discussed by contrasting coal formed gas with oil type gas.The results reveal that the carbon isotope of gas alkyl hydrocarbon has following characteristics:with the increase of carbon number,the δ13C frequency range of methane and its homologues reduces,and the main frequency value gets heavier;④compared with oil type gas,coal formed gas has lower δ13C₁ main frequency peak values and higher δ13C₂ values;㈣the correlation betweenΔ(δ13C₂-δ13C₁)and δ13C₁ is negative;there are only two types of carbon isotope series for coal formed gas,that is,positive and reversed carbon isotope series;the characteristics of carbon isotope series for gas alkyl hydrocarbon depend on microcomponents,evolutionary degree and pool forming mechanism.