Genetic identification of natural gases from shallow reservoirs in some oil- and gas-bearing basins of China  

作　　者：王万春 刘文汇 徐永昌 沈平 康晏 任军虎 

机构地区：[1]Key Laboratory of Gas Geochemistry, Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou 730000, China,Graduate School, Chinese Academy of Sciences, Beijing 100039, China [2]Key Laboratory of Gas Geochemistry, Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou 730000, China

出　　处：《Chinese Journal Of Geochemistry》2005年第1期90-94,共5页中国地球化学学报

基　　金：ThisworkwasfinanciallysupportedbytheMinistryofScienceandTechnologyofChina(GrantNo.2001CB209102)andtheNationalNaturalScienceFoundationofChina(GrantNo.40072049)

摘　　要：Natural gases of shallow reservoirs with the carbon isotopic compositions of methane ranging from -50‰ to -60‰ (PDB) were considered as mixed gases of biogenic and thermogenic origins previously and some of them were considered as low-mature (or low temperature thermogenic) gases lately. In this paper natural gases with the carbon isotopic compositions of methane in the above range were identified using the molecular and stable carbon isotopic compositions of methane, ethane and propane. The mixed gases of biogenic and mature thermogenic origins display the characteristics of {δ{}+{13}C-1} ranging from -50‰ to -60‰, {δ{}+{13}C-2}>-35‰, Δ values ({δ{}+{13}C-3}-{δ{}+{13}C-2})< 5‰ and C-1/∑C++-2 ratios < 40. Immature to low|mature gases display the characteristics of {δ{}+{13}C-1} ranging from -50‰ to -60‰, {δ{}+{13}C-2} < -40‰, Δ values ({δ{}+{13}C-3}-{δ{}+{13}C-2}) >7‰, and C-1/∑C++-2 ratios >60.Natural gases of shallow reservoirs with the carbon isotopic compositions of methane ranging from -50‰ to -60‰ (PDB) were considered as mixed gases of biogenic and thermogenic origins previously and some of them were considered as low-mature (or low temperature thermogenic) gases lately. In this paper natural gases with the carbon isotopic compositions of methane in the above range were identified using the molecular and stable carbon isotopic compositions of methane, ethane and propane. The mixed gases of biogenic and mature thermogenic origins display the characteristics of {δ{}+{13}C-1} ranging from -50‰ to -60‰, {δ{}+{13}C-2}>-35‰, Δ values ({δ{}+{13}C-3}-{δ{}+{13}C-2})< 5‰ and C-1/∑C++-2 ratios < 40. Immature to low|mature gases display the characteristics of {δ{}+{13}C-1} ranging from -50‰ to -60‰, {δ{}+{13}C-2} < -40‰, Δ values ({δ{}+{13}C-3}-{δ{}+{13}C-2}) >7‰, and C-1/∑C++-2 ratios >60.

关 键 词：天然气 浅储集层 碳同位素 地质勘探 

分 类 号：P618.13[天文地球—矿床学]