华北中元古界古潜山是我国北方主要规模化开发的地热储层,具有储热量大、埋藏浅和易回灌等特点。古潜山热储受物性特征、空间展布和地质构造等因素制约,控热机制多元,传热过程复杂,针对其热成因机制的研究一直受到重视。本文以雄安新区古潜山热储为研究对象,基于近年来雄安新区地热勘探井资料分析,提出了华北古潜山热储优势流传热理论,古潜山热储的热源主要来自深部幔源传热,而壳源热流低于30 mW/m²,华北克拉通破坏后,随着岩石圈拉张减薄,地幔热对流增强,形成了由深到浅的优势传热通道,地表热流通量升高。古潜山高热导率储层形成了热在垂向和水平向上向储层聚集的传导优势热流,流体在高孔渗碳酸盐岩储层中循环形成了对流优势热流,断裂加剧了传导和对流沿构造方向的聚热效应。在热量聚集作用下,古潜山不同构造部位钻孔测温曲线表现出5种类型,分别为传导型、传导—对流—传导型、传导—对流—弱对流型、传导—强对流型和传导—弱对流型等。断裂带为地下热水的循环和热的富集提供了空间优势流动通道,通过靠近容城断裂的典型钻孔温度测井结果,建立解析方程计算容城断裂地下水热对流占比为29.2%。本研究通过综合分析古潜山优势流传热的影响因素,为华北地热成因模式研究提供了新的思路。

Buried-hill reservoirs are the primary geothermal reservoirs widely developed in northern China. They are characterized by significant heat storage capacity, shallow depth, and easy re-injection. The reservoirs, constrained by their physical properties, spatial distribution, and geological structures, have diverse heat control mechanisms and complex heat transfer processes, and recent research is focused on the heat transfer and accumulation mechanisms. In this paper, based on the analysis of geothermal exploration wells constructed in Xiong’an, we propose a theory of dominant heat transfer in the buried-hill geothermal field of North China. According to this theory, the heat source of the buried-hill reservoirs originates mainly from the deep mantle, while the crustal heat flow is less than 30 mW/m. The enhanced mantle convection from the destruction of the North China Craton (NCC) leads to dominant heat flow from the deep mantle to shallower depths, and with the tensile thinning of the lithosphere in the NCC the surface heat flow increases significantly. The high thermal conductivity buried-hill reservoirs creates conductive dominant heat flow, vertically and horizontally, towards the carbonate reservoirs, while fluid circulation in the highly porous carbonate reservoirs creates convective dominant heat flow. Faulting exacerbates the conduction and convection heat gathering effect along the fault direction. The temperature profiles of boreholes at various sites in the buried hill exhibit five types: conduction, conduction-convection-conduction, conduction-convection-weak convection, conduction-strong convection, and conduction-weak convection. The percentage of thermal convection in groundwater in the Rongcheng Fault was calculated to be 29.2%. Through comprehensive analysis of the influencing factors of the dominant heat flow and heat accumulation in the buried-hill geothermal field, this research provides new insights into the heat transfer mechanism in North China.