新疆芦草沟组烃源岩显微组分及其孔隙发育特征

The maceral and pore-developed characteristics in soure rocks of Lucaogou formationin Xinjiang

对新疆二叠系芦草沟组的烃源岩,同时制备自然断面和氩离子抛光面,在场发射扫描电镜下,观测显微组分及其孔隙发育特征。结果表明,芦草沟组的显微组分按原始质料可划分为低等浮游生物和高等植物;主要显微组分是以低等浮游生物为原始质料的沥青质体。自然断面上沥青质体的赋存状态有条带状、薄膜状、交互状;抛光面上沥青质体的赋存状态有散块状、条带状、填隙状、封裹状等,这些赋存状态反映出了有机质与矿物质有交替沉积、充填胶结、化学分异等3种成因关系。沥青质体含量多,分布广,气孔发育,是重要的生烃组分。以高等植物为原始质料的角质体、丝质体、镜屑体等均以碎屑的形式掩埋于泥质中,粒度大于泥粒级颗粒。有些碎屑状显微组分虽有较强的生烃能力,但因总体上含量少,分布分散,对油气形成贡献不大;可另一方面,碎屑状显微组分提高了总有机碳含量。显微组分及其气孔发育程度是研究区烃源岩生烃潜力评价的两个重要指标。

By the field emission scanning electronic microscope （SEM）, the maceral and pore-developed characteristics are observed on the natural section and polished surface in somre rocks of Pemfian Lucaogou for- marion in Xinjiang. The results show that, the maceral of Pemfian Lucaogou fomlation is classified as lower plankton and advanced plants from raw material. The maceral is mainly bituminite with lower plankton as raw materiah The occmTence for bituminite on the natural section are identified as the banded, the filmy and the intergrowth, on polished surface are scattered patches, the banded, the interstitial, and the sealing in shape, and the occunrence provides three genetic relationships for organic and minerals, such as alternating deposi- ting, filling and cementation, and chemical differentiation. The bituminite is significant hydrocarbon-derived composition, with high content, extensive, and developed gas pores. The cutinite, fusinite, and vitriniteclas- tics formed by advanced plants are buried in argillaceous by debris, and the grain sizes are larger than clay fraction particles. Although some of maceral elastics with high hydrocarbon generated capacity, generally with low content and dispersive distribution, maceral clastics don＇t have too much contribution to oil and gas forma- tion, despite increasing total organic carbon content. Maceral and gas pores are important index for hydrocar- bon generation potential evaluation.