增强型地热系统(EGS)储热量评估的三维模糊反演模型研究

Efficient exploitation and usage of enhanced geothermal systems (EGS) provide wide prospect for energy revolution. There has been a spate of interest in the resource assessment of EGS because of the uncertainties of the thermo-physics parameters of EGS. Aiming to resolving the scientific problems of accurate determination of thermal parameters of EGS reservoirs, this study will develop fuzzy inference methods for solving three-dimensional stead-state inverse heat-conduction problems; we designed a research methodology of combining direct-inverse heat transfer modeling, model calibration, experimental validation, and high-performance numerical calculation, whereby only finite temperature measurements of testing wells are used as the inputs, and geometric boundary, boundary conditions, and heat resources can be estimated by the fuzzy inference. The research also aims to explore the objective functions and sensitivity equations of unknown parameters, and to reveal the impacts of testing point positions and error levels on the solution of the inverse problem. It is expected to provide theoretic foundation of solving inverse problems of three-dimensional stead-state heat conduction, and provide scientific basis of the engineering applications of resource assessment for EGS.

增强型地热系统（EGS）的有效开发利用将为能源革命提供广阔的前景，资源评估受到地热参数不确定性的约束已经成为研究热点。针对EGS热储层热物理参数难以精确测定的难点问题，建立三维稳态导热反问题的模糊推理方法对储量参数进行反演计算。采用传热学正/反问题的理论建模、模型校核、模型的实验验证和高性能数值计算相结合的研究方案，将有限个测试井的测试温度作为模型输入，采用模糊推理算法，对储层的热物性参数、几何边界、边界条件和热源进行参数反演，进而建立热物理参数与储热量之间的数量关系；探索待求参数的目标函数及其敏度计算公式，揭示热储层温度测点位置和误差水平对反问题求解结果的影响。为热储层三维稳态导热反问题求解提供科学基础，并为增强型地热系统资源勘探与利用提供理论依据。

增强型地热系统（EGS）的有效开发利用将为能源革命提供广阔的前景，资源评估受到地热参数不确定性的约束已经成为研究热点。针对EGS热储层热物理参数难以精确测定的难点问题，本项目采用传热学反问题的方式对储量参数进行反演计算。在热储层稳态导热正问题的建模过程中，发现渗流边界条件下地热储层的地热温度与地温梯度均高于无渗流条件下地热储层相对应的值，即证实可通过不同的地热温度，以及地温梯度反演出地热储层边界的渗流情况等边界条件，再进一步得出温度场并计算地热储层的热资源。在热储层稳态导热反问题数学模型的建立过程中，从热储层的热源参数、天然裂缝参数与储层温度场之间的联系出发，通过获取热源参数、代表裂缝分布的热物性参数分布来获取增强型地热系统热储的温度分布。反演的结果不仅可以用来进行地热资源储量计算，也可以作为裂缝发育潜力评估的科学依据。在对反演模型进行数值理论分析后，可将裂缝岩体传热学反问题实验台测得的温度作为真实测点温度输入到反演模型进行反演计算，利用数值校验和实验相结合双重验证地热反演模型的可靠性。