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琼东南盆地渐新统崖城组和陵水组发育泥岩、碳质泥岩和煤3类潜在油气源岩,但由于岩屑样品大多受到泥浆添加剂污染,利用经典的热解技术(Rock-Eval)和元素分析法都无法客观评价有机质的生烃特性。针对这种情况,采用干酪根裂解色谱质谱技术(PY-GC-MS)研究了琼东南盆地渐新统崖城组和陵水组烃源岩有机质的生烃特性。研究表明,该两套地层沉积有机质以Ⅱ偏Ⅲ型为主,生烃潜力属中—差水平。但相比之下,崖城组源岩生烃潜力普遍较好,而陵水组仅局部层位(主要是陵三段)可发育好的烃源岩。由于该区潜在烃源岩主要发育于滨海—沼泽和浅海环境,受区域性海侵影响大,相变快,因此,优质烃源岩不可能成片成带展布,其发育主要受控于沉积所处空间位置是否近岸和近岸区域生态系统是否具有高的生产率两个因素。这一研究结论与中海油研究中心对该两套烃源岩所作生烃潜力统计结果相一致。
There are three types of potential source rocks of mudstone, carbonaceous mudstone and coal in Yacheng Formation and Lingshui Formation of Qiongdongnan Basin. However, most of the cuttings samples are contaminated by mud additives. By using classical pyrolysis technique (Rock-Eval) And elemental analysis are unable to objectively evaluate the hydrocarbon generation characteristics of organic matter. In response to this situation, the kerogen characterization of organic matter in the Yacheng Formation and the Lingshui Formation of the Qiongdongnan Basin was studied using kerogen pyrolysis chromatography-mass spectrometry (PY-GC-MS). The results show that the sedimentary organic matter of the two sets of strata is dominated by type II and type Ⅲ, and the potential for hydrocarbon generation is of medium-to-poor level. However, in contrast, the hydrocarbon generation potentials of the Yacheng Formation source rocks are generally better, whereas the source rocks of the Lingshui Formation can be well developed only in the local strata (mainly the third member of the Lingtang Formation). As the potential source rocks in this area are mainly developed in the coastal-marsh and shallow sea environment, they are greatly affected by regional transgression and rapidly changing in phase. Therefore, the source rocks of high quality are unlikely to be distributed into a belt and their development is mainly controlled by Whether the spatial location of the sediment is near or not and the near-shore ecosystems have high productivity are two factors. The conclusion of this study is in line with the statistical results of the hydrocarbon generation potentials of these two sets of source rocks by CNOOC Research Center.