塔里木盆地海相原油热裂解的阶段性特征及其意义  

Multiple stages of marine oil cracking from the Tarim Basin:Insights from thermal simulation experiments

作　　者：路清华[1,2] 黄继文 顾忆[1,2] 丁勇 夏永涛[3] 孙永革[1,4] LU Qinghua;HUANG Jiwen;GU Yi;DING Yong;XIA Yongtao;SUN Yongge(Wuxi Research Institute of Petroleum Geology,SINOPEC Petroleum Exploration and Production Research Institute,Wuxi 214126,Jiangsu,China;SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms,Wuxi 214126,Jiangsu,China;Petroleum Exploration&Production Research Institute,SINOPEC Northwest Oilfield Company,Urumqi 830011,Xinjiang,China;School of Earth Sciences,Zhejiang University,Hangzhou 310027,Zhejiang,China)

机构地区：[1]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 [2]中国石化油气成藏重点实验室,江苏无锡214126 [3]中国石化西北油田分公司勘探开发研究院,新疆乌鲁木齐830011 [4]浙江大学地球科学学院,浙江杭州310027

出　　处：《地球化学》2024年第2期174-182,共9页Geochimica

基　　金：国家自然科学基金项目(42030803);中国石化科技部科技攻关项目(P18059-3)联合资助。

摘　　要：塔里木盆地台盆区深层油气勘探不断取得突破,原油热稳定性及其裂解特征已成为制约塔里木盆地深层下一步油气勘探与评价的瓶颈之一。本研究选择塔河地区未遭受明显次生改造原油,采用黄金管封闭体系热压模拟实验,在恒压、程序升温条件下,系统分析不同热演化阶段原油热裂解产物与残余物的分子组成。结果表明,随着热演化程度的增加,伴随着原油热裂解程度增加引起的化合物裂解、环化、芳构化作用,气体和液态烃产率呈现显著的阶段性变化,并显示不同的分子地球化学特征,据此分为3个阶段:①初始裂解期(Easy Ro<1.2%),与原始油样比较,残留产物全烃色谱特征未发生显著变化;②主裂解期(1.2%<Easy Ro<3.8%),又以Easy Ro=2.0%为界分为快速裂解阶段和缓慢裂解阶段,残留产物中正构烷烃含量逐渐降低,同时伴随低环数芳烃化合物含量的逐渐增加,而稠环芳烃含量的逐渐增加则与低环数芳烃含量逐渐减少相对应;③裂解末期(3.8%<Easy Ro<4.5%),以高含量稠环芳烃的富集为标志,其中残留物全烃色谱上以四环芳烃占绝对优势。研究结果对有效描述原油的热演化过程、明确原油不同热裂解阶段油气产物的组成和产率特征以及深层原油热稳定性评价具有重要指导意义。With the recent breakthrough of the Tarim Basin during deep-buried petroleum exploration and exploitation,the thermal stability of crude oil and its associated cracking processes are becoming one of the most urgent issues.In this study,thermal simulation experiments using a gold tube close pyrolysis system were conducted to investigate marine oil cracking processes in terms of product yields and molecular composition dynamics with respect to the maturity sequence.One crude oil without significant secondary alteration was collected from the Tahe area of the Tarim Basin.Although demethylation,cyclization,and aromatization dominate the oil cracking processes with increasing thermal maturation,the gas and liquid hydrocarbon yields show multiple stage features,and each stage is characterized by distinctive molecular compositions.Thereby,three cracking stages are defined,i.e.,the primary stage(Easy Ro<1.2%),the main stage(1.2%<Easy Ro<3.8%),and the late stage(3.8%<Easy Ro<4.5%).The whole hydrocarbon gas chromatogram of residues from the primary cracking stage displays a pattern similar to that of the original oil.The main cracking stage can be subdivided into quick and slow cracking stages by a maturity boundary of Easy Ro=2.0%.The significant enrichment of mono-and di-aromatic hydrocarbons accompanied by gradual depletion of n-alkanes in residues marks the beginning of the main cracking stage.Compared with mono-and di-aromatic hydrocarbons,the increase in polynuclear aromatic hydrocarbons in residues indicates the occurrence of the slow cracking stage.The late stage is characterized by relatively high concentration of polynuclear aromatic hydrocarbons like chrysene in this experiment.This study provides a potential guideline to quantitatively characterize oil cracking processes,with a combined probing of gas and liquid hydrocarbon yields and molecular compositions,and has important implications for the thermal stable evaluation of crude oil in deep-buried reservoirs.

关 键 词：海相原油 热模拟实验 原油裂解阶段性 深层油气 塔里木盆地 

分 类 号：P618.13[天文地球—矿床学]