镜状体反射率可作为下古生界高过成熟烃源岩成熟度标尺

14 Take Vitrinite like Reflectance as the Maturity lndicator for Lower Paleozoic High-Overmature Source Rock

镜状体是我国下古生界高过成熟烃源岩中常见的显微组分，它主要来源于藻类及其降解产物热解成烃后原地残留物。镜状体反射率随埋深加大呈线性增加。根据对奥陶系主要成烃母质粘球形藻和相同热成熟度的黄县褐煤热模拟残渣的对比分析，建立了镜状体（ＶＬ）、粘球形藻藻类体、镜质体（Ｖ）光性演化的相关关系，镜质体和镜状体反射率关系表示为ＶＲｏ＝０．５３３ＶＬＲｏ＋０．６６７。镜状体反射率作为下古生界烃源岩有机成熟度指标主要适用于镜质体反射率１．０％～２．０％Ｒｏ阶段。

Vitrinite-like macerals always exists in the Lower Paleozoic high-overmature sourcerock,which mainly originated from residuse of algae andit′sdegradation products after pyrolysis.The vit-rinite-like reflectance increase with the burial depth linearly.Basedd on the comparison of Gloeocapsomorphaprisca,the main Ordovician hybrocarbon generating parent,and the residues of Huanxian lignite that hasthe same thermal maturity,the correlatiom between optical evolution of vitrinte-like(VL),Gloeocapso-mirpha prisa and vitrinite(V)is established.The rilationship between vitrinite reflectance and the Paleo-nite-like reflectance expresses VR0=0.533VLRO+0.667.As the thermal maturty indeq for Lower Paleo-zoic source rock,the vitrinite-likw reflectance is suitable for vitrimite vitrinite for vitrinite reflectance ranges from 1.0% to 2.0%