沧县隆起北部地温场特征及其主控因素分析

沧县隆起北部地区地热资源丰富,但关于地热田的形成机制与主控因素仍存在争议。通过收集区域地质资料和井温资料,并结合热传导正演模拟,系统地分析了研究区内地温梯度横向与垂向的特征、不同地质条件下地温场的分布规律,并正演了两条实测地热剖面,分析了研究区内地温场分布的主控因素。研究表明,横向上地温梯度在凸起区相对较高,凹陷区相对较低,与基岩起伏具有良好的对应关系,并且垂向上地温梯度的变化可分为两段,在浅部沉积盖层较高,以热传导为主,下部的寒武系、奥陶系和蓟县系储层地温梯度较低,以热对流为主。同时,区内地温场的分布主要受基岩埋深所控制,局部地区受到地下热水沿断层上涌所影响。通过研究,将为今后的地热开发选址提供重要依据。

Characteristics and Major Controlling Factors of Geothermal Field of North Cangxian Uplift

The northern part of Cangxian uplift is rich in geothermal resources,but the formation mechanism and major controlling factors of geothermal fields are still controversial.Based on the compilation of regional geological and well-temperature data,and integrated with forward modeling of heat conduction,we systematically analyze the horizontal and vertical temperature gradient characteristics in the study area,and the distribution patterns of geothermal field under different geological conditions.We then forward-model two measured geothermal profiles to analyze the major controlling factors of local thermal field distribution.The results show that the horizontal geothermal gradient is relatively high in the salient area,but relatively low in the depression area,which corresponds well with the bedrock undulation.The vertical geothermal gradient can be divided into two sections:the shallow sedimentary caprock is higher and of mainly heat conduction,whilst the lower thermal reservoir is lower in the Cambrian,Ordovician and Jixian reservoirs,and mainly of thermal convection.Meanwhile,the local thermal field distribution is mainly controlled by the bedrock burial depth,and(in some places)is also affected by the upwelling of underground hot-water along faults.This study provides an important basis for future selection of geothermal development sites.