渤海湾盆地南乐地热田特征及其成因分析

为探究渤海湾盆地南乐地热田的岩溶热储特征及地热田成因机制，基于物探和地质资料，对渤海湾盆地南乐次凸地热田的热储展布规律、水化学特征、运移通道以及地温场等因素进行了剖析，构建了地热田成因概念模型。研究表明:南乐次凸地热田存在加里东、印支-海西、燕山、喜山4期奥陶系风化壳岩溶热储，顶板埋深1 427~2 135 m，有效厚度累计46.2~91.7 m；具有良好的盖层，地温梯度高达3.04~3.24℃/hm，地下水类型为SO₄+Cl-Na+Ca-B型；地热田形成于较高的大地热流、渤海湾陆内裂陷盆地-东濮凹陷西斜坡带背景下，受西部太行山区和东部鲁西南山区裸露基岩大气降水的共同补给，进入基岩的冷水深部循环受到热流的"热折射""热流再分配"效应以及兰聊断裂摩擦生热等的共同加热、增温，沿区域内不整合面以及断裂向上运移、富集，最终形成了以奥陶系为热储的传导型地热田系统。南乐次凸地热田奥陶系岩溶热储可采地热资源量为1.02×109 GJ，折合标煤3.50×107 t，可满足供暖面积12.37×104万m2，具有良好的开发市场前景。研究成果对南乐地热田乃至渤海湾盆地的岩溶热储开发利用具有较好的指导意义。 

Characteristics and mechanism analysis of geothermal field in Nanle Sub-uplift,Bohai Bay Basin

In order to explore the characteristics of karst reservoir and the genetic mechanism of the Nanle geothemal field in Bohai Bay Basin.Based on geophysical and geological data, this paper analyzes the factors of the geothermal field that include karstic reservoir distribution, hydro-chemical characteristics, migration channels and geothermal, and eventually we construct the conceptual model of the geothermal field. The results show that there are four stages of Ordovician weathering crust karst heat reservoirs in the Nanle geothermal field, including Caledonian, Indo-Hercynian, Yanshan and Xishan. The burial depth of the Ordovician karstic reservoir is 1 427-2 135 m (effective thickness: 46.2-91.7 m). The reservoir is characterized by good caprock and geothermal gradient (3.04-3.24℃/hm), and the groundwater is SO₄+Cl-Na+Ca-B type. It is considered that the geothermal field is a conductive one, which was formed in the west slope belt of Dongpu Sag-intracontinental basin in the high heat flow. And the system is characterized by the cold water that deep into the bedrock of cycle that influenced by thermal refraction and redistribution effect of heat flow and friction heat generation of Lanliao fault, which along the regional unconformity and fracture migration, enrichment, whose recharged water source comes from atmospheric precipitation in the Taihangshan and Luxinan, and finally concentrated in Ordovician karst heat reservoir of the Nanle Sub-uplift. The total extractable geothermal resource of the Ordovician karstic reservoir in the Nanle Sub-uplift geothermal field is 1.02×109 GJ (3.5×107 t standard coal eqv.), and the annual geothermal resource can meet the indoor heating demand of 0.124 million square meter. The geothermal field has a good market potential.The results have a good guiding significance for the development and utilization of karst reservoirs in the south of Bohai Bay Basin-Nanle geothermal field.