角质体热解产烃的实验研究

Experimental Study of Hydrocarbon-generating Potential of Cutinite through Open-system Pyrolysis

本文在严格的煤岩显微组分分离富集的基础上,采用岩石热解、热解气相色谱以及开放体系下热模拟等方法,系统地对贵州水城上二叠统龙潭组(P_3l)煤中角质体的生烃潜力、热解烃组成特征、生烃模式进行了研究。结果显示:角质体具有很高的生烃潜力,其S_1+S_2为308.33mg/g,远高于丝质体(S_1+S_2为26mg/g)和基质镜质体(S_1+S_2为192mg/g),而与树皮体(S_1+S_2为297mg/g)相当。另外,角质体为一种好的生油组分,其热解烃中油占了67％(197.47mg/g);角质体热解产物主要为碳数较低的正构烷烃、烯烃化合物,此外苯、烷基苯(甲苯、二甲苯)、萘系化合物所占比例较高,而姥鲛烷和植烷含量则较少。本区角质体的主要生烃区间介于420～450℃之间(对应的R_o为1.1％～1.5％),生烃高峰在425～435℃范围内,最大产烃率对应的温度为430℃。角质体这种生烃潜力高,并且在高成熟度下大量生烃的特点对在成熟度普遍较高的华南地区寻找油气田具有重要的现实意义。

Cutinite is one of the major macerals for hydrocarbon generation, the hydrocarbon potential of which is important in the evaluation of oil and gas resources derived from coals. In this paper, methods such as Rock-Eval, Py-Gc and experimental simulation via an open-system were used to study the hydrocarbon potential, hydrocarbon composition and hydrocarbon-generation model of cutinite from barkinite-rich coals in the Shuicheng area, Guizhou Province, Southwest China. The results show that cutinite has a high hydrocarbon potential, with Si + S2 being 308 mg/g, which is higher than that of fusinite (S1+S2 = 26 mg/g,), desmocollinite (S1+S2 = 192 mg/g) and barkinite (S1+S2 = 297 mg/g). Cutinite can produce large amounts of hydrocarbons at the high-maturity stage, mostly within the temperature range of 420~450℃ (corresponding to Ro1. 1%~1. 5%), and hydrocarbon-generating peaks range from 425℃ to 435℃. Cutinite is one of the best oil-source rocks, with oil accounting for 67% (197. 47 mg/g rock) of the total hydrocarbons. Alkanes and alkene are the dominant hydrocarbons, beside these, there contain high contents of aromatic hydrocarbons (such as benzene, toluene, xy-lene and naphthalene) and minor isoalkanes (such as pristane and phytane). These characteristics of cutinite are of practical importance in the explorationi of oil and gas resources in the Late Permian Longtan Formation coals, South China.