CAJ | 학술논문

对松辽盆地徐家围子断陷庆深气田天然气组分、碳氢同位素和稀有气体同位素的分析表明,天然气以烷烃气为主,烷烃气碳同位素组成随着碳数增加呈变轻趋势,且δ13C1>-30‰, R/Ra一般大于1.0,δ13CCO2值介于-16.5‰~-5.1‰之间；氢同位素组成δD1=-205‰~-197‰,平均值为-203‰,δD2=-247‰~-160‰,平均值为-195‰,δD3=-237‰~-126‰,平均值为-163‰,且存在氢同位素组成倒转现象,即δD1>δD2<δD3。根据对庆深气田天然气不同地球化学特征分析,认为该气田烷烃气中重烃主要为有机成因,而 CH4有相当无机成因混入。庆深气田烷烃气氢同位素组成具有 CH4变化小,而重烃(δD2,δD3)变化大的特点。根据与朝阳沟地区天然气烷烃气氢同位素组成对比分析,认为 CH4主要表现为无机成因,而重烃气(δD2,δD3)主要为有机成因,且无机成因CH4氢同位素组成重于有机成因CH4。
대송료분지서가위자단함경심기전천연기조분、탄경동위소화희유기체동위소적분석표명,천연기이완경기위주,완경기탄동위소조성수착탄수증가정변경추세,차δ13C1>-30‰, R/Ra일반대우1.0,δ13CCO2치개우-16.5‰~-5.1‰지간；경동위소조성δD1=-205‰~-197‰,평균치위-203‰,δD2=-247‰~-160‰,평균치위-195‰,δD3=-237‰~-126‰,평균치위-163‰,차존재경동위소조성도전현상,즉δD1>δD2<δD3。근거대경심기전천연기불동지구화학특정분석,인위해기전완경기중중경주요위유궤성인,이 CH4유상당무궤성인혼입。경심기전완경기경동위소조성구유 CH4변화소,이중경(δD2,δD3)변화대적특점。근거여조양구지구천연기완경기경동위소조성대비분석,인위 CH4주요표현위무궤성인,이중경기(δD2,δD3)주요위유궤성인,차무궤성인CH4경동위소조성중우유궤성인CH4。
By measuring chemical compositions, carbon and hydrogen isotope compositions and noble gas isotopes of natural gases from the Qingshen gas field, Songliao Basin are characterized by a dominant component of alkanes gases, enrichment of 12C with increasing molecular weight, heavyδ13C1 values (δ13C1>-30‰), R/Ra>1.0, andδ13CCO2 values ranging from-16.5‰to-5.1‰. The distributive range of theδD1,δD2,δD3 values for natural gases from the Qingshen gas field are -205‰ to -197‰ (average values = -203‰), -247‰ to -160‰ (average value=-195‰),-237‰to -126‰(average value=-163‰) , respectively, associated with a partial reversal of the hydrogen isotopic trend of C1-C3 alkanes, i.e. δD1> δD2< δD3. Based on the geochemical parameters of natural gases from the Qingshen gas field, the heavy hydrogen gases were derived from the thermal decomposition of organic matter, whereas partial concentration of methane might be entrapped from the abiogenic alkanes and mixed with thermogenic alkanes. A narrow distribution of methaneδD values and a large range ofδD values of C2 and C3 are observed in the Qingshen gas field. By comparison with the hydrogen isotopic compositions of gaeous alkanes in the Chaoyanggou region, methane in the Qingshen gas field is partially from abiogenic gas, and the heavy hydrocarbon gases (δD2, δD3) are mainly derived from organic matters, with the δD values of abiogenic methane higher than those of thermogenic methane.