塔里木盆地玉北地区埋藏史及热史分析

摘要

According to strata division data and the palaeo heat flow analysis,the authors simulated and analyzed the burial and thermal histories of 5 representative drillings in Yubei area,Tarim Basin.In this way,the thermal evolution and maturation processes of source rock are discussed and the mature stages of hydrocarbon source rock and hydrocarbon generation period are pointed out preliminarily in the study area.The research results show that the study area experienced several cycles of sedimentary burial,uplift and erosion during the deposition of Cambrian to Devonian.After the sedimentation of Devonian,Carboniferous-Permian layers show characteristics of sedimentary burial.In the Mesozoic,a few Triassic layers,having been eroded in the eastern of Yubei area,appeared sedimentary discontinuity in the central and western regions.In the Cenozoic,the strata deposited continuously and the deposition rate presented an increasing trend.In the study area,after the Cambrian hydrocarbon source rock had deposited,the maturity evolution appears relatively successive.Cambrian source rock came into the oil-generating window in the Ordovician,and the time of the hydrocarbon generation is early.In the Silurian-Devonian,influenced by the Early Hercynian,the strata underwent the uplift and erosion,and the evolution of the source rock was slow.With the stable sedimentary and the active volcano widely in Carboniferous-Permian,the source rock entered into the high mature stage.Because of the remote effect of the Himalaya Orogeny,with the area subsiding and very thick sediments deposited in the Cenozoic,the source rock reached the over-mature stage,where the gas gets generated.%根据地层分层数据和古热流分析,对塔里木盆地玉北地区的5口代表性钻井进行了埋藏史、热史的模拟与分析,探讨了研究区烃源岩的热演化成熟过程,初步划分了烃源岩的成熟阶段和生烃期次.研究结果认为:玉北地区寒武系-泥盆系沉积时期,具有多次沉积埋藏和隆升剥蚀的交替;泥盆系沉积之后,石炭-二叠系呈现沉积埋藏的特征;中生代在玉北地区东部少量沉积三叠系,随后被剥蚀,而在中西部发生沉积间断;进入新生代,地层持续沉积,且沉积速率呈现增大趋势.研究区寒武系烃源岩自沉积以来成熟度演化相对连续,奥陶纪时进入生烃门限,成熟时期较早;志留-泥盆纪,受海西早期运动的影响,发生隆升剥蚀作用,烃源岩演化变缓;石炭-二叠纪受控于区域上持续稳定的地层沉积与广泛发育的火山活动,研究区寒武系烃源岩进入中高成熟阶段;由于喜马拉雅造山运动的远程效应,新生代研究区持续沉降,形成巨厚沉积,烃源岩成熟度达到高-过成熟,为天然气生成阶段.