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碳酸盐岩是否为有效烃源岩一直存在不同观点。从有机岩石学方法入手,以沥青为研究对象,开展了低成熟泥灰岩烃源岩生烃、饱和原油白云岩原油裂解的模拟实验,并对各模拟温度点的样品,以及四川盆地寒武系页岩、震旦系—寒武系碳酸盐岩样品进行了沥青鉴定、定量及反射率测定。结果表明,不同模拟阶段的泥灰岩中沥青含量呈现出由低至高再降低的趋势,高成熟早期为沥青形成高峰期;泥灰岩烃源岩、寒武系页岩烃源岩中沥青赋存方式受有机质发育程度及非均质性影响,主要呈分散状分布,但在烃源岩的微孔缝发育处,沥青则呈相对富集状或脉状,震旦系—寒武系泥质碳酸盐岩中检测到与烃源岩中赋存状态一致的沥青(原生沥青),是其生烃的有效证据之一;白云岩原油裂解实验中沥青含量由高至低变化,沥青充填在孔隙和粒间缝中,呈粒状、块状或脉状分布,是储层次生运移沥青;烃源岩中镜质体反射率与沥青反射率之间具有较好的相关性,可用等效镜质体反射率来反映烃源岩成熟度;同一温度下,储层沥青反射率明显高于烃源岩沥青反射率,利用储层沥青反射率来反映烃源岩成熟度时会出现比实际偏高的现象。
Whether or not carbonate rocks are effective source rocks has varied from point of view. Starting from the organic petrology method, taking bitumen as the research object, the simulation experiments on the generation of low-mature marl source rock and the cracking of saturated crude oil dolomite crude oil were carried out. The samples at each simulated temperature point and the Cambrian Shale, Sinian-Cambrian carbonate samples were tested for bitumen identification, quantification and reflectance measurements. The results show that the bitumen content of marlite in different simulation stages shows the trend of decreasing from high to low, and the peak of bitumen formation is formed in the early stage of high maturity; the marl source rocks in marlstone and the bitumen in the Cambrian shale source rocks The storage mode is affected by the degree of organic matter development and heterogeneity, and is mainly distributed in a distributed manner. However, the bitumen is relatively enriched or veined in the pores of the source rock. The Sinian-Cambrian mud Bitumen (primary bitumen), which is consistent with the occurrence state of source rock in the source rocks, is one of the most effective evidences for hydrocarbon generation. The content of bitumen in the dolomite oil cracking experiment varies from high to low, In the pores and intergranular cracks, granular, block or vein distribution, reservoir secondary migration of asphalt; source rocks in the vitrinite reflectance and the asphalt reflectivity has a good correlation between available The vitrinite reflectance reflects the maturity of source rock. At the same temperature, the reflectance of reservoir bitumen is obviously higher than that of source rock, and the reflectance of reservoir bitumen reflects the maturity of source rock Higher than the actual phenomenon.