Zhang Hui, Zhao Weibo, Wang Huaichang, Guo Huijuan, Peng Ping'an
Institute of Exploration, Development and Research, PetroChina Company Limited Changqing, Oilfield Branch, Xi'an 710018, China.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
ACS Omega. 2024 Sep 26;9(40):41389-41395. doi: 10.1021/acsomega.4c04220. eCollection 2024 Oct 8.
Vitrinite reflectance is the most widely used parameter for reconstructing the thermal history of sedimentary basins and evaluating the maturation of source rocks. However, suppression of vitrinite reflectance has also been reported, which could affect the accuracy of evaluating the degree of thermal evolution. In this article, the influence of hydrocarbon generation on vitrinite reflectance during thermal evolution is studied based on thermal simulation experiments in a closed system. The results show that hydrocarbon absorption and overpressure can lead to the suppression of vitrinite reflectance. For values between 0.6% and 2.1%, the suppression of vitrinite reflectance is primarily attributed to the impregnation of the telocollinite texture with hydrocarbons generated from type I kerogen. At values exceeding 2.1%, overpressure becomes the dominant cause of the anomalous reflectance. Under closed-system conditions, the retention of volatile products within the pore network of vitrinite hinders the structural reorganization, leading to reflectance suppression.
镜质体反射率是重建沉积盆地热历史和评估烃源岩成熟度最广泛使用的参数。然而，也有报道称镜质体反射率会受到抑制，这可能会影响热演化程度评估的准确性。本文基于封闭系统中的热模拟实验，研究了热演化过程中烃类生成对镜质体反射率的影响。结果表明，烃类吸收和超压会导致镜质体反射率受到抑制。对于0.6%至2.1%之间的值，镜质体反射率的抑制主要归因于I型干酪根生成的烃类对镜质组结构的浸染。当值超过2.1%时，超压成为反射率异常的主要原因。在封闭系统条件下，镜质体孔隙网络中挥发性产物的保留阻碍了结构重组，导致反射率受到抑制。
