沉积有机质二次生烃有机岩石学特征

采用自然演化系列与预热残渣热模拟系列相结合的方式,对异常地热场条件下的沉积有机质二次生烃有机岩石学特征进行探讨,表明沉积有机质二次生烃有机组份及其组合不同于一次连续演化生烃,除具有正常的显微组份外,还具有体现二次演化特征的热变组份和热变次生组份。热变组份保持原来的组份结构,但光性出现各向异性,包括热变镜质组、热变壳质组和热变惰质组;热变次生组份具有不同于泥炭化时期所成的显微组份结构特征,往往具有较为强烈的光学各向异性。沉积有机质二次演化显微组份组合特征与起始成熟度密切相关,低熟和高熟沉积有机质显微组份光性和结构改变小,成熟沉积有机质改变显著。以起始成熟度为根据,以显微组份成因、光学性质和结构构造为依托,对沉积有机质二次生烃显微组份进行科学分类。探讨了热变次生显微组份的可能成因,指出中间相的产生和发展是热变次生显微组份形成与否的关键因素。

ORGANIC PETROLOGIC CHARACTERISTICS OF SECONDARY HYDROCARBON GENERATION FROM SEDIMENTARY ORGANIC MATTERS

Under a condition of the abnormal high geothermal field, the organic petrologic characteristics of the sedimentary organic matters in the process of secondary hydrocarbon generation were brought to light with the both nature and artificial maturity sample series. This analysis indicated that the macerals and maceral groups of the sedimentary organic matters of secondary hydrocarbon generation might be different from that of the continuous hydrocarbon generation. Except for the common macerals, the thermal macerals and the thermal secondary macerals were found, which were special type macerals of the sedimentary organic matters of secondary hydrocarbon generation. The thermal macerals kept the original structure, but appeared optical anisotropy. They could be divided into three groups: thermal vitrinite, thermal exinite and thermal inertinite groups. The structure of the thermal secondary maceral was different from that forming in the period of peatification. They appeared a strongly optical anisotropy, similar to the thermal exinite. The organic petrologic characteristics of secondary hydrocarbon generation from the sedimentary organic matters were nearly correlation with their initial maturity. Based on the initial maturity, the formation cause, the optical and the structure characteristic of the macerals, the macerals and the maceral groups of secondary hydrocarbon generation from the sedimentary organic matters in the conditions of the abnormal high geothermal field were classified. The interphase forming and development might be a key factor of the thermal secondary macerals formation.