深部地热水多开采井联合运行模式优化

A joint operation mode of multi-production wells for deep geothermal water exploitation

  • 摘要: 深部地热水作为一种清洁低碳的可再生能源,对促进实现“双碳”目标具有重要意义,但其不合理开采将导致水量减少、水位下降、工程效益低等一系列问题。以河南开封市城区已有的地热井勘探资料为基础,构建表征地热水运移的水文地质模型及对应的数学模型,利用Galerkin有限单元法对模型进行识别与验证。针对现有地热井单独运行、按需开采的弊端,围绕开封市城区主采的埋深1 200~1 400 m热储层,以水位降深最小、井间干扰最小、运行费用最低为目标函数,以水位降深、供需平衡为约束条件,建立地热水开采井运行模式优化模型。为提高收敛的准确性和结果可靠性,引入Pareto-灰狼算法求解模型并用TOPSIS理论对结果进行排序。研究表明:优化后剖分节点水位降深之和减少70.3%,地热井之间水位降深影响值之和减少10.83%,分区Ⅰ、Ⅱ、Ⅲ水位降深分别减少12.85%、28.14%、43.77%,−80 和−90 m水位等值线包围的降落漏斗面积分别降低15.5%和28.7%,地热井运行总费用降低28.7%。研究成果通过构建优化模型和引入改进算法,为地热水合理开发提供科学依据,优化地热水开采井的运行模式,不仅可以减少水资源浪费,提高水资源利用效率,还可以降低地热井运行费用,对于地热水合理开发与科学保护具有重要指导作用。

     

    Abstract: Deep geothermal water, a type of clean and low-carbon renewable energy, plays a significant role in achieving the goals of peak carbon dioxide emissions and carbon neutrality. However, its irrational exploitation will lead to many problems such as decreased water quantity, lowered water level, and low engineering benefits. Based on the available exploration data of geothermal wells in the urban area of Kaifeng City, Henan Province, this study constructed a hydrogeological model used to characterize the migration of geothermal water and a corresponding mathematical model, which was identified and verified using the Galerkin finite element method. Focusing on geothermal reservoirs at burial depths ranging from 1200 to 1400 m that are primarily exploited in the urban area of Kaifeng City, this study built an optimization model for the operation mode of production wells, aiming to overcome the drawbacks of isolated operation and on-demand exploitation of existing geothermal wells. In this model, the objective functions comprised the minimum drawdown, inter-well interference, and operating cost, and the constraint conditions included drawdown and the supply-demand balance. To improve the convergence accuracy and result reliability of the optimization model, this study solved the model using the Pareto-Grey Wolf Optimizer and ranked the results based on the TOPSIS theory. After optimization, the sum of drawdowns at partition nodes decreased by 70.3%, the sum of influenced drawdowns between geothermal wells decreased by 10.83%, and drawdowns in zones I, II, and III decreased by 12.85%, 28.14%, and 43.77%, respectively. The areas of the cones of depression surrounded by the -80 m and -90 m water-level contours decreased by 15.5% and 28.7%, respectively. Additionally, the total operating cost of geothermal wells decreased by 28.7%. By building an optimization model and introducing an improved algorithm, this study will provide a scientific basis for the rational exploitation of geothermal water. Optimizing the operation mode of geothermal wells can reduce the waste of water resources and improve their utilization efficiency while reducing the operating cost of geothermal wells. This study can serve as an important guide for the rational exploitation and scientific protection of geothermal water.

     

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