采暖尾水回灌对砂岩热储地温场的影响——以鲁北地区为例

Effect of heating tail water recharge on geothermal field of sandstone heat storage:A case study in northern Shandong Province

为保证地热资源可持续开发利用,深入开展回灌工程采灌井合理井距研究、防止短时间内发生热突破是地热领域的重大关切。本文根据全井段测温结果,对砂岩热储不同采灌工程地温场变化特征进行了分析。研究表明:随着回灌年度的增加,冷水范围越来越大,热量对回灌井有效补给路径变长,回灌井热储段温度曲线波动幅度越小;当采灌井距较小、底部温度相对较低时,回灌冷水会对开采井造成影响,致使开采井热储温度降低;在回灌初期热对流在热量恢复中占主导作用,随着回灌年数的增加,冷水范围越来越大,热对流对温度场恢复的作用逐渐减弱,周边和相邻隔水层热传导在温度恢复中的作用越来越显著,温度恢复越来越慢,因此,在规模化回灌条件下,热突破是必然的。

In order to ensure the sustainable development and utilization of geothermal resources, it is of great concern in the field of geothermal to carry out in-depth research on reasonable distance between production and reinjection wells in recharge engineering and prevent thermal breakthrough in a short time. Based on the temperature measurement results of the whole well, the variation characteristics of geothermal field in different mining and irrigation projects of sandstone heat storage are analyzed in this paper.The results show that with the increase of recharge years, the range of cold water becomes larger, the effective recharge path of heat to the recharge well becomes longer, and the fluctuation range of the temperature curve of the heat reservoir of the recharge well becomes smaller.When the distance between the production and irrigation wells is small and the bottom temperature is relatively low, the recharge cold water will affect the production wells, resulting in the decrease of the heat storage temperature of the production wells.Heat convection plays a leading role in heat recovery at the initial stage of recharge, and with the increase of recharge years, cold water range becomes larger, the effect of heat convection on the recovery of temperature field is weakened gradually;Meanwhile, The heat conduction of the surrounding and adjacent impervious layers plays an increasingly significant role in temperature recovery, and the temperature recovery becomes slower, therefore, under the condition of large-scale recharge, thermal breakthrough is inevitable.