【摘要】 在分析内因（有机质类型、有机质成熟度）与外因（生物降解、运移）对天然气中丁烷地球化学特征影响的基础上,探讨了丁烷在天然气研究中的应用。首先明确了内因、外因对丁烷地球化学特征的影响:腐殖型有机质生成的煤型气iC₄/nC₄值、δ¹³C₄值均高于腐泥型有机质生成的油型气;iC₄/nC₄值随成熟度增加而降低,且在成熟阶段快速降低、进入高成熟阶段后缓慢降低;微生物降解会使得天然气中iC₄/nC₄值增大,且降解作用越强iC₄/nC₄值越大。而目前有关运移是否会影响iC₄/nC₄值及如何影响iC₄/nC₄值还存在较大争议。发现丁烷在天然气生物降解、天然气成因、天然气成熟度等研究中都有较好的应用:iC₄/nC₄值能有效判识天然气是否发生生物降解,生物降解气iC₄/nC₄值大于2、普遍大于3,iC₄/nC₄值大于3可以判定天然气发生生物降解,未降解气iC₄/nC₄值小于3、普遍小于2,iC₄/nC₄值小于2可以判定天然气未发生生物降解;iC₄/nC₄值、δ¹³C₄值均能有效判识受外因影响较小天然气的成因,其判别标准分别为油型气iC₄/nC₄值小于0.8、煤型气iC₄/nC₄值大于0.8与油型气δ¹³C₄值小于-26‰、煤型气δ¹³C₄值大于-26‰;iC₄/nC₄值对天然气成熟度判识也有重要作用。iC₄/nC₄值示踪天然气运移存在多解性,其有效性也明显不如其他指标,应慎重选择其示踪天然气运移。更多还原

【Abstract】 Based on comprehensive analysis of internal factors（i.e.,organic matter type and organic matter maturity） and external factor（i.e.,biodegradation and migration） on characteristics of butane,the application of geochemical characteristics of butane was studied.The paper cleared the effects of internal factors on characteristics of butane.The coal type gas derived from humic organic matters, "which had the higher iC₄/nC₄ ratio and δ¹³ C₄ value than the oil type gas from sapropellic organic matters.The iC₄/nC₄ ratio decreased with the increase of maturity,and it decreased quickly at the mature stage and slowly at the highmature stage.The iC₄/nC₄ ratio would increase as the biodegradation increases,and the stronger the biodegradation,the higher the iC₄/nC₄ ratio.Whether the migration would affect the iC₄/nC₄ ratio and how it affects,both are uncertain.It is found that the butane can provide information about the biodegradation,genesis and maturity of natural gas.The iC₄/nC₄ ratio can be used to effectively determine the gas is biodegraded or normal.The iC₄/nC₄ ratios of biodegraded gas were higher than 2 and most of them were higher than 3.If the iC₄/nC₄ ratio is higher than 3,the natural gas is biodegraded gas.The iC₄/nC₄ ratios of normal gas were lower than 3 and most of them were lower than 3,if the iC₄/nC₄ ratio is lower than 2,the natural gas is normal gas.For the gas suffered less influence by external factor,the oil type " which has iC₄/nC₄ ratios lower than 0.8 and δ¹³ C₄ value lower than-26‰,the coal type gas which has iC₄/nC₄ ratios higher than 0.8 and δ¹³ C₄ value higher than-26‰.The iC₄/nC₄ ratios can help analyze the maturity of natural gas.For the iC₄/nC₄ as trace index,there are still more controversial and poor effectiveness,and should be carefully to choose it for tracing migration.更多还原