川西地区浅、中层天然气藏化探判别模型

川西地区上沙溪庙组储层的物上气甲烷、丙烷、重烃,酸解烃甲烷、丙烷、重烃,荧光320 nm和360 nm等浓度指标及物上气湿度系数、物上气丙烷/甲烷、酸解烃湿度系数、酸解烃丙烷/甲烷、荧光360 nm/320 nm、荧光405 nm/320 nm等比值指标均明显高于蓬莱镇组储层,具有显著的浓度降或浓度正向梯度,确实存在烃类的垂向微运移。上沙溪庙组储层天然气三维荧光图谱具有明显的T₂峰,峰型相对复杂,与蓬莱镇组储层具有显著的差异性。聚类、模糊聚类、因子分析、非线性映射和对应分析等可以很好地将蓬莱镇组、上沙溪庙组储层划分为两大类,反映了蓬莱镇组和上沙溪庙组储层具有良好的自然分群特征及可判别性。依据费歇尔准则建立的判别模型表明,物上气甲烷作用最大,反映了物上气在井中化探判别天然气储层中的重要作用。

Discriminant model of geochemical prospecting for shallow and Medium depth gas reservoirs in western Sichuan

For the Shaximiao Formation reservoirs in western Sichuan,both the concentration indexes(such as the methane,propane and heavy hydrocarbon of headspace analysis,the methane,propane and heavy hydrocarbon of acidolysis-hydrocarbon analysis,and the fluorescence 320 nm and 360 nm) and the ratio indexes(such as headspace humidity coefficient,headspace propane/methane,acidolysis hydrocarbon humidity coefficient,acidolysis hydrocarbon propane/methane,and fluorescence 360 nm/320 nm and 405 nm/320 nm),are obviously higher than that in Penglaizhen Formation reservoirs.Decrease or positive gradient of hydrocarbon concentrations are noticeable,suggesting that hydrocarbon vertical micro-migration do occur.The 3D fluorescence spectrum of natural gas in Shaximiao Fm reservoirs has apparent T