塔东地区侏罗系生烃史  

History of Hydrocarbon Generation of Jurassic in Tadong Area,Tarim Basin

作　　者：王飞宇[1] 李谦[1] 张水昌 陈建平 罗键 肖中尧[3] 

机构地区：[1]石油大学石油天然气成藏机理教育部重点实验室,北京102200 [2]中国石油油气地球化学重点实验室,北京100083 [3]中国石油塔里木油田分公司勘探开发研究院,新疆库尔勒841000

出　　处：《新疆石油地质》2004年第1期19-21,共3页Xinjiang Petroleum Geology

摘　　要：对塔东地区10口探井110个侏罗系源岩样品进行了系统的有机质成熟度分析,其镜质体反射率(Ro)主体为0.50%～0.65%,烃源岩均处在未熟-低熟阶段。塔东地区中新生界地层镜质体反射率梯度仅0.17%/km,这一数值明显低于库车前陆盆地(约0.23%/km～0.25%/km),这与塔东区新生代以来地温梯度较低有关。塔东地区现今地温梯度约为19～22℃/km.根据华英参1井古温标重构了塔东地区古地温演化,表现为地温梯度在中新生代总体上不断降低,中生代为32～28℃/km,新生代为28～21℃/km.根据探井和人工井成熟度演化史分析,塔东地区中侏罗统源岩成熟度演化呈现以下特点:在白垩纪,中侏罗统源岩均处于未成熟阶段;在早第三纪末(23×106a),一部分中侏罗统源岩已处于临界成熟状态(Ro为0.5%～0.6%);至12×106a,大部分中侏罗统源岩仍处于临界成熟状态,但已有一小部分处于凹陷带的源岩镜质体反射率略高于0.6%;现今中侏罗统源岩大部分仍处于低成熟阶段(Ro为0.5%～0.7%)。塔东地区侏罗系有效烃源灶(Ro>0.7%)的分布有限,这是目前认为塔东地区发现的的天然气或原油并非源于侏罗系煤系源岩的根本原因。The Jurassic strata in Tadong area of Tarim basin are a set of coal measure source rocks mainly distributed in the Mi ddle Jurassic.The organic matter maturities of110Jurassic source rock sample s from10drilling wells in Tadong area are systematically analyzed,showing tha t all Middle Jurassic source rocks are in the immature-low mature phase,in whi ch the virinite reflectance(R o )ranges generally from0.50%～0.65%,while the vitrinite reflectan ce gradient during Mesozoic and Cenozoic in Tadong area is only0.17%/km i n average,which is less than that of Kuqa foreland basin(0.23%～0.25 %/km).This is related to low geothermal gradient during Cenozoic in this ar ea.The present geothermal gradient of Ta-dong area is about 19～22℃/km .According to reconstructed paleo-geothermal evolution of Well HYC-1,the ge othermal gradient trends to decline in total during Mesozoic and Cenozoic(32 ～28℃/km for Mesozoic;28～21℃/km for Cenozoic).Based on the analyse s of maturity evolution history of drilled wells and pseudo wells,the Middle Ju rassic source rocks in Tadong area are characterized by the following:during Cr etaceous,they are in immature stage;by the end of Paleogene(23Ma),a part of them has been in critical mature status(R o is about 0.5%～0.6%);by the end of Miocene(12Ma),most of them are still in the critical mature status other than a minor part in sag zone wit h R o >0.6%;up to now,most of them are still in low mature stage(R o is about 0.5%～0.7%).The limited distribution of effective source kitchen(R o >0.7%)of Jurassic in Tadong area is a fundamental reason for those:th e oil and gas found in Tadong area to date are not originated in the Jurassic co al measure source rocks.

关 键 词：有机质成熟度 烃源岩 地温梯度 地层镜质体 侏罗统 

分 类 号：TE122.1[石油与天然气工程—油气勘探] P534.52[天文地球—古生物学与地层学]