四川盆地大地热流特征及热储系统类型

Characteristics of terrestrial heat flows and types of thermal reservoir systems in the Sichuan Basin

四川盆地地热资源类型多、储量大,可利用总量位居全国第3位,具备地热资源开发利用的基础。为进一步明确盆地的热体制对区域地热能资源评估的作用,根据四川盆地内钻井的基本地热参数与盆地构造演化过程,系统研究了盆地热流分布及主控因素、热储系统类型以及有利地热资源分布。研究结果表明:①四川盆地沉积地层的热结构分为3种,分别为受控于基底热流背景与裂陷槽岩石热导率差异的加里东阶段热结构;受控于峨眉大火成岩省玄武岩喷发及盆地拉张作用的海西阶段热结构;受盆缘强烈造山运动形成的中新生代热结构。②提出了震旦纪—早寒武世与晚二叠世—中三叠世封闭型层控热储系统与开放型断褶热储系统2类、3种热储系统类型。③明确了断裂带深循环地热资源、强构造背景下的异常高温地热资源与早期深埋地热资源3类有利地热资源类型及其优势分布区。结论认为,四川盆地地热资源勘探开发潜力巨大,取得的认识对四川盆地地热资源的勘查与评价具有重要的促进和推动作用。

The geothermal resources in the Sichuan Basin are of multiple types and great reserves and their total utilization volume ranks the third in China,so there is a foundation for the development and utilization of geothermal resources.In order to further clarify the role of the thermal regime in the Sichuan Basin in the assessment of regional geothermal energy resources,this paper systematically studies the thermal flow distribution and its main controlling factors,the types of thermal reservoir systems and the distribution of favorable geothermal resources in the Sichuan Basin based on the basic geothermal parameters of the wells in this basin and the tectonic evolution process here.And the following research results are obtained.First,the thermal structures in the Sichuan Basin are classified into three types,i.e.,the Caledonian thermal structure controlled by the background of basal heat flow and the difference in thermal conductivity of rift trough rocks,the Hercynian thermal structure controlled by the basalt eruption in the Emei Igneous Province and the tension in the basin,and the Middle Cenozoic thermal structure formed by strong orogenesis along the basin margin.Second,two categories of thermal reservoir systems are proposed,namely Sinian–Early Cambrian and Late Permian–Middle Triassic closed layer-controlled thermal reservoir system and open fault-folded thermal reservoir system,which are further classified into three types.Third,it is confirmed that there are three types of favorable geothermal resources,including deep circulation geothermal resources in faulted zones,abnormally high temperature geothermal resources under the background of strong structure,and early deep-buried geothermal resources,and their dominant distribution areas are also defined.In conclusion,the exploration and development potential of geothermal resources in the Sichuan Basin is huge,and the research results are of great significance to the prospecting and evaluation of geothermal resources in the Sichuan Basin.