蒸发分馏作用对原油中金刚烷类化合物分布与组成的影响——以塔里木盆地库车坳陷羊塔克构造上的原油为例

Effect of evaporative fractionation on the distribution and composition of diamondoids in crude oils: a case study of crude oils from Yangtake structure, Kuqa Depression, Tarim Basim

杨茜 包建平 倪春华 朱翠山

YANG Xi BAO Jianping NI Chunhua ZHU Cuishan

油气地球化学与环境湖北省重点实验室(长江大学 地球化学系), 武汉 430100 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126

Hubei Key Laboratory of Petroleum Geochemistry and Environment, Geochemistry Department, Yangtze University, Wuhan, Hubei 430100, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

借助于色谱和色谱—质谱分析技术，对塔里木盆地库车坳陷羊塔克构造上两组原油中烃类组成进行了系统分析，以研究蒸发分馏作用对金刚烷类化合物分布与组成特征的影响。轻烃分析结果表明，YT5和YT101井两组原油都经历了蒸发分馏作用的改造，其中上部储层产次生凝析油，而下部储层产经蒸发分馏作用改造的残留油。相似的甾、萜烷分布与组成表明两组原油具有相同的来源。金刚烷类分析结果表明，蒸发分馏作用对次生凝析油和残留油中单金刚烷和双金刚烷系列的相对组成基本没有影响，但对它们的浓度影响显著，如次生凝析油中金刚烷类化合物的浓度远高于残留油，且单金刚烷系列浓度升高的幅度远大于双金刚烷系列，但对金刚烷类成熟度参数影响甚微。因此，金刚烷类化合物的浓度不适用于判断遭受蒸发分馏作用改造原油的成熟度，但相关成熟度参数仍能正常使用。

Two sets of crude oil samples from the Yangtake structure in the Kuqa Depression of Tarim Basin were analyzed with the aid of GC and GC-MS to evaluate the effect of evaporative fractionation on the distribution and composition of diamondoid hydrocarbon in crude oils. The light hydrocarbon signatures of oils from wells YT 5 and YT 101 indicate secondary products of evaporative fractionation for the condensates from the upper reservoirs, and the oils from the lower reservoirs are residuals. Moreover, the distribution and composition of steranes and terpanes in two sets of crude oils appeared to be comparable, suggesting that these oils shared a same source. Evaporative fractionation has imperceptible effect on the distribution and relative abundance of alkyl admantanes and diamantanes, but their concentrations in secondary condensates and residual oils appeared to be significantly varied. For example, the concentration of diamondoids in secondary condensates is much higher than that in residual oils, and the increasing extent of concentration for alkyl admantanes in secondary condensates is much higher than that in residual oils. Therefore, it should be very cautious to use the concentration of diamondoids to determine the degree of maturity of crude oils if evaporative fractionation occurred. However, the effect caused by evaporative fractionation to the maturity parameters such as MAI and MDI is relatively minor and they can still be used as indicators to evaluate maturity of crude oils even with the alteration of evaporative fractionation.

国家自然科学基金 41772199;国家自然科学基金 41272169

https://doi.org/10.11781/sysydz202202295