川西北低成熟沥青产气特征及生烃动力学应用  

Characteristics of gas generation and the application of hydrocarbon generation kinetics from low-maturity asphalt in Northwestern Sichuan Basin

作　　者：王自翔[1,2] 王永莉[1] 吴保祥[1] 孙则朋 汪亘[1,2] 徐亮[1,2] 朱深圳 孙丽娜[1,2] 

机构地区：[1]甘肃省油气资源研究重点实验室中国科学院油气资源研究重点实验室中国科学院地质与地球物理研究所兰州油气资源研究中心,甘肃兰州730000 [2]中国科学院大学,北京100049

出　　处：《石油学报》2016年第3期339-347,共9页Acta Petrolei Sinica

基　　金：国家重点基础研究发展计划(973)项目(2012CB214701);中国科学院战略性先导科技专项(XDB03020405;XDB10030404);国家自然科学基金项目(No.41572350;No.41172169);甘肃省重点实验室项目(1309RTSA041);西部之光计划联合学者项目资助

摘　　要：选择川西北矿山梁地区低成熟沥青,采用封闭金管-高压釜体系,以20℃/h和2℃/h的升温速率进行生烃热模拟实验,分析了气体产物组分、产率和烃类气体碳同位素组成及变化特征。结果表明,沥青具有较强的产气潜力,是一种重要的生气有机母质;甲烷、乙烷和丙烷气体的碳同位素值分别为-50.85‰^-37.53‰、-37.93‰^-13.75‰和-37.10‰^-6.45‰。低演化阶段出现δ13C2>δ13C3,之后,不同碳数烃类气体碳同位素组成关系为δ13C1<δ13C2<δ13C3。沥青热模拟甲烷最终碳同位素值为-37.53‰,轻于川中威远地区震旦系—寒武系常规天然气(-32.3‰^-34.7‰)和页岩气(-35.1‰^-37.3‰)的甲烷碳同位素值。川中威远地区常规天然气可能为具较重甲烷碳同位素的干酪根裂解气与具较轻甲烷碳同位素的原油裂解气的混合气。而页岩气中则可能富含更多的原油裂解气,干酪根裂解气相对较少。将生烃动力学结果应用到川中高科1井可见,早—中侏罗世,寒武系烃源岩进入主生油期,生成原油排出,部分进入到震旦系继续生气,侏罗纪进入主生气期及其在早白垩世后期进入生气末期,气态烃转化率达94%,比残留在寒武系中的沥青多约20%。The low-maturity asphalt in Kuangshanliang Area,Northwestern Sichuan Basin is selected for thermal simulation experiments of hydrocarbon generation using sealed gold tube-autoclave system at the heating rate of 20℃ / h and 2℃ / h,aiming to analyze the gas product components,yield,carbon isotopic composition and variation characteristics of hydrocarbon gases. The results show that asphalt presents a high gas generation potential as an important organic matter for gas generation; the carbon isotopic values of methane,ethane and propane are within the range of- 50. 85‰ and- 37. 53‰,- 37. 93‰ and- 13. 75‰,as well as- 37. 10‰ and- 6. 45‰,respectively.When δ13C2> δ13C3exists in the low evolution stage,the relationship of carbon isotopic compositions for hydrocarbon gases with different carbon numbers is δ13C1< δ13C2< δ13C3. The final carbon isotopic value of methane is- 37. 53‰ obtained through asphalt thermal simulation,lighter than those of conventional natural gas( within the range of- 32. 3‰ and- 34. 7‰) and shale gas( within the range of-35. 1‰ and- 37. 3‰) in Sinian-Cambrian reservoirs,Weiyuan Area,Central Sichuan Basin. In Weiyuan Area,conventional natural gas may be hybrid gas consisting of kerogen pyrolysis gas with heavier carbon isotopes of methane and crude oil cracking gas with lighter carbon isotopes of methane. However,shale gas may contain more crude oil cracking gas and less kerogen pyrolysis gas. The hydrocarbon generation kinetics results are applied in Well Gaoke 1,and the results indicate that Early-Mid Jurassic was the main oil generation period for Cambrian strata,and some crude oil expelled into Sinian reservoirs for further hydrocarbon generation. The major and late gas generation periods were Jurassic and the late Early Cretaceous,respectively. The conversion rate of gaseous hydrocarbon reached 94%,more than that of residual asphalt in Cambrian reservoirs by about 20%.

关 键 词：四川盆地 沥青 碳同位素 生烃动力学 高科1井 生烃史 

分 类 号：TE122.1[石油与天然气工程—油气勘探]