塔里木盆地的热流、深部温度和热结构  

Heat flow,deep formation temperature and thermal structure of the Tarim Basin,Northwest China

作　　者：刘绍文[1,2] 李香兰[1,2] 郝春艳[1,2] 李旭东[1,2] 

机构地区：[1]南京大学海岸与海岛开发教育部重点实验室,江苏南京210023 [2]南京大学地理与海洋科学学院,江苏南京210023

出　　处：《地学前缘》2017年第3期41-55,共15页Earth Science Frontiers

基　　金：国家自然科学基金项目(41272143);中国石油科技创新项目(2015D-5006-0105)

摘　　要：盆地热状态研究不仅对于探讨盆地成因演化动力学具有重要约束作用,也能为盆地油气资源评价提供基础地热参数。塔里木克拉通是我国三大古老陆块之一,其上叠合发育了我国内陆最大的海相沉积盆地,油气潜力大,是当前油气勘探的主力区块。塔里木盆地热状态早期研究都基于石油钻孔的试油温度数据,由于缺乏稳态的高精度地温测量,制约了对盆地精准热状态的认识。我们近年来对塔里木盆地开展了高分辨率稳态深井温度测井,并结合大量的岩石热物性参数测试,深入分析了塔里木盆地现今热状态及深部热结构特征。塔里木盆地地温梯度在15~30℃/km,热流为26~66mW/m^2,平均热流为43mW/m^2。相比其他盆地而言,塔里木具有低温冷盆的热状态,并与世界上典型的前寒武克拉通具有相似的地热背景。塔里木盆地自二叠纪以来无大的构造-热事件扰动,因故整体热状态偏低,盆内局部热异常与局部构造、基底形态或岩性横向差异引起的热折射效应等有关。塔里木盆地深部地温的横向分布特征受到盆地基底格局控制,盆地1 000m埋深处的温度为29~41℃,平均为35℃;3 000m的温度为63~100℃,平均为82℃;5 000 m的温度为97~160℃,平均为129℃。盆地古生界海相烃源岩底界埋深处的地层温度整体仍处于液态窗之内。塔里木盆地长期的低温背景和深埋过程是盆地油气形成和保存的关键地热条件。塔里木盆地热流配分表明,地壳热流占地表热流的主导,其中,沉积盖层的放射性生热约占盆地地表热流的20%,估算的地幔热流为6~15mW/m^2,这一范围与世界上前寒武克拉通的地幔热流一致。塔里木盆地和青藏高原存在显著的地热差异,且这一继承性热差异可追溯至印度-欧亚大陆碰撞之前,地热差异引起两大构造区的深部岩石圈的流变学和强度存在强烈的非均质性,从而造就了目前观测的差异活动构The geothermal regime of a sedimentary basin not only provide constraints on the treatments of basin formation and evolution, but also offers basic geothermal parameters for the hydrocarbon resource assessment. As one of the three Precambrian blocks in China, the Tarim craton, the largest superimposed sedimentary basin, is also a main target in a current hydrocarbon exploration with great potential. Although considerable advancement has been made on the basin＇s geothermal regime during the last few decades, nearly all the temperature data used in previous studies were formation testing temperatures from exploration boreholes. These temperature data lacked confidence to some extent, due to insufficient time allowed to reach steady-state at the time of measurements. Recently, we have conducted the steady-state temperature logging in the Tarim Basin and measured abundant data on rock thermal properties, which enabled us to re-visit the thermal regime. Our results demonstrate that the present-day geothermal gradient for the Tarim Basin varies from 15 to 30℃/km, while heat flow ranges from 26 to 66 mW/m^2 with a mean of 43 mW/m^2. These new data confirm that the Tarim Basin has a relatively low heat flow and shares similar geothermal regime with other Precambrian cratons in the world. Furthermore, spatial distribution of the estimated formation temperature at the depth of 1 - 5 km within the basin is also similar and mainly controlled by the crystalline basement pattern. In general, temperatures at the depth of I km range between 29 and 41 ℃ with a mean of 35 ℃, while at 3 km they vary from 63 to 100 ℃ with a mean of 82 ℃ ; at 5 km below the surface, temperatures fall into a range between 90 and 160 ℃ with a mean of 129 ℃. In addition, the estimated formation temperatures at the bottom surfaces of the Paleozoic marine source rocks are still within the oil window. Hence we further propose that the long-term low geothermal background and large burial depth are the favorable conditions for hy

关 键 词：热流 热结构 地层温度 液态窗 塔里木盆地 

分 类 号：P314[天文地球—固体地球物理学]