塔里木盆地中央隆起区现今地温场分布特征及其与油气的关系  

Present-Day Geotemperature Field Characteristics in the Central Uplift Area of the Tarim Basin and Implications for Hydrocarbon Generation and Preservation

作　　者：冯昌格[1] 刘绍文[2] 王良书[1] 李成[1] 

机构地区：[1]南京大学地球科学与工程学院,江苏南京210093 [2]海岸与海岛开发教育部重点实验室,南京大学地理与海洋科学学院,江苏南京210093

出　　处：《地球科学（中国地质大学学报）》2010年第4期645-656,共12页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金(Nos.40504013;40634021);中国石油中青年创新基金(No.07E1033);高等学校博士点基金项目(No.20060284040)

摘　　要：沉积盆地热状态研究不仅对于理解盆地成因演化具有重要意义,而且还与油气生成和保存息息相关.根据塔里木盆地中央隆起区近120口钻井的试油温度资料和296块岩石热导率的测试结果,获得了该区现今地温梯度、深部温度(1000～5000m埋深及烃源岩顶界面)及大地热流的分布特征.结果表明,该区热状态整体偏低(平均地温梯度为23.3℃/km,平均大地热流为47.3mW/m2),二叠纪的岩浆活动对现今地温场已无影响.不同埋深的地层温度表现出与地温梯度及大地热流相似的分布模式,即隆起区高、凹陷区低,这一展布特征受基底起伏和形态控制.烃源岩顶部温度表明,巴楚组、卡拉沙依组和良立塔格组等烃源岩层目前仍处于油气的有利保存状态;巴楚隆起、卡塔克隆起西北部和古城墟隆起东部的中下寒武统烃源岩则处于良好的油气保存状态,其他地区处于不利的油气保存状态.特别是,该区已探明的油气田往往位于相对高温区,并提出深部热流体的向上运移和聚集过程可能是造成异常高温的因素.这一发现表明盆地现今地温场特征与油气田分布具有良好的对应关系,可为今后油气勘探提供地热学依据.Study of geothermal regime of sedimentary basin is not only vital for understanding the formation and evolution of the basin, but also is of significance for oil and gas generation and preservation in the basin. Temperature data from about 120 exploration wells and measured values of thermal conductivity of 296 rock samples from Tarim basin are used to calculate the present-day geothermal gradient, subsurface formation temperature at the depths of 1 000-5 000 m and the top of source rocks concerned, respectively. The results show that thermal regime of the area is relatively lower with an average geothermal gradient of 23. 3 ℃/km and heat flow of 47. 3 mW/m^2 ; suggesting that the Permian intensive magmatism in the Tarim basin has no obvious effect on the present-day temperature field. The general pattern of subsurface temperature distribution at different depths is similar to that of the geothermal gradient and heat flow and is featured by higher parameters in the uplift areas and lower ones in the depressions, indicating the influence of base topography configuration on the temperature field. The source rocks of the Bachu Formation, Kalasbayi Formation and Lianglitage Formation in the area are predicted to be within favorable hydrocarbon preservation condition now, while the middle and lower Cambrian source rocks are in the Bachu uplift, northwestern Katake uplift and eastern Guchengxu uplift areas, and the unfavorable preservation condition is inferred in other left region.Particularly, it is found that the discovered oil and gas fields are usually accompanied by anomalous high temperature, and the upward migration and accumulation of hot fluid below is speculated to explain this perfect coincidence. The finding of temperature pattern and distribution of oil and gas field can provide some insights for future exploration.

关 键 词：地温梯度 地温场 大地热流 地下温度 塔里木盆地 中央隆起. 

分 类 号：P314[天文地球—固体地球物理学]