南方海相志留系页岩有机质类型恢复研究

Restoration of organic matter type in Silurian marine shale, South China

张琴 王红岩 拜文华 吝文 杜东

中国石油勘探开发研究院廊坊分院，河北 廊坊 065007 国家能源页岩气研发（试验）中心，河北 廊坊 065007 中国石油勘探开发研究院，北京 100083

中国南方下古生界海相志留系龙马溪组页岩分布广、厚度大，有机碳质量分数高，成熟度高，大部分处于高—过成熟度阶段，导致大部分有机质类型判别指标失效。文中通过对沉积在相似环境的三叠系未成熟泥岩样品的热模拟实验，确定了页岩原始生烃潜力的恢复图版，并以此为基础，对高成熟度志留系页岩的原始有机碳和有效碳质量分数进行恢复，进而利用页岩恢复原始状态后的降解率和氢、氧指数对页岩有机质类型进行了确定。研究结果表明，南方志留系页岩有机质类型以Ⅰ型为主，兼有Ⅱ型，具有间接型页岩生气特点。

Silurian Longmaxi Formation shales are characterized by wide distribution, large thickness, high TOC and high maturity in Lower Palaeozoic marine of South China, and most of them are at high mature-post mature stage, which results in the ineffectiveness of most distinguish indices of organic matter types. In this paper, the restoration plate of the original hydrocarbon generation potential of the shale is established through the thermal simulation experiment of the Triassic prematurity shale with similar sedimentary environment to Silurian shale in the study area. With the restoration plate, the original TOC of the Silurian shale with high maturity is restored. Then, the organic matter type is determined through the degradation ratio, hydrogen index and oxygen index after the restoration of shale original state. The result shows that the organic matter type is mainly Type Ⅰand Type Ⅱ, which are characterized by indirect shale gas generation.

10.6056/dkyqt201302005