川中油气区金华地区大安寨段及须五段烃源岩生物标志物特征和生源构成

Biomarker characteristics and biogenetic composition of source rocks of Da′anzhai member and Xujiahe 5 member in Jinhua area of central Sichuan oil and gas region

川中油气区金华地区侏罗系油气勘探开发取得较大进展,侏罗系发育多套油气供烃层位。采用饱和烃气相色谱、色谱质谱等技术,细致对比并揭示了研究区自流井组大安寨段和须家河组五段(简称须五段)烃源岩的地球化学特征,探讨了2套主要供烃层位烃源岩的沉积环境和生源构成特征。结果表明,大安寨段烃源岩的分子地化特征与须五段烃源岩差异较大:大安寨段烃源岩中等姥植比(Pr/Ph),中等三环萜烷参数(C1_(9+20)TT/C_(23)TT),中等降藿烷/藿烷系列化合物(C_(30)D/C_(30)H)、早洗脱重排藿烷/藿烷系列化合物(C_(30)E/C_(30)H),高降藿烷/升藿烷(C_(27)D/C_(27)R),相对低三芳甾烷参数(C_(27)/C_(28)TAS),生源构成以菌藻生源为主,兼有丰富的高等植物生源的混源输入;须五段烃源岩呈现低中等Pr/Ph,低C_(19+20)TT/C_(23)TT、C_(30)D/C_(30)H、C_(30)E/C_(30)H,中等C_(27)D/C_(27)R,相对高C_(27)/C_(28)TAS,生源构成以高等植物生源为主。

Great progress has been made in the exploration and development of Jurassic oil and gas in Jinhua area of central Sichuan oil and gas region,in which many sets of oil and gas supply horizons have been developed.By using saturated hydrocarbon gas chromatography and chromatography-mass spectrometry,the geochemical characteristics of the source rocks of the Da′anzhai member of Ziliujing Formation and the fifth member of Xujiahe Formation(Xujiahe 5 member for short)in the study area were compared and analyzed in detail,and the sedimentary environment andbiogenetic composition characteristics of source rocks of two sets of main hydrocarbon supply horizons were alsodiscussed.The results show that the molecular geochemical characteristics of the source rocks of Da′anzhai member are quite different from those of Xujiahe 5 member.The source rocks of Da′anzhai member have medium Pr/Ph ratio,medium tricyclic terpene parameters(C_(19+20)TT/C_(23)TT),medium haloalkanes/hopanes parameters(C_(30)D/C_(30)H),early elution rearranged hopanes/hopanes(C_(30)E/C_(30)H),high haloalkanes/hopanes parameters(C_(27)D/C_(27)R),and relatively low triarylsterane parameters(C_(27)/C_(28)TAS),showing that the biogenic composition is dominated by bacteria and algae,with abundant mixed input of higher plant biogenic sources.The source rocks of Xujiahe 5 member have the characteristics of low to medium Pr/Ph,low C_(19+20)TT/C_(23)TT,C_(30)D/C_(30)H and C_(30)E/C_(30)H,medium C_(27)D/C_(27)R and relatively high C_(27)/C_(28)TAS,showing that the biogenic composition of the source rocks of Xujiahe 5 member is mainly higher plants.