共和盆地储层干热岩人工裂隙与流体传热机理及热能效应研究

Accurate measurement of heat transfer characteristics between the hot dry rock artificial fractures and fluid is an important basis for the design of hot dry rock geothermal system. The field test is not only high cost and lack of general applicability due to different geological conditions. Although the numerical simulation is simple, but need experimental data to verify. Select the Gonghe basin hot dry rock reservoir cores and rock outcrops, and use similar theoretical to construct artificial fracture of the exploitation hot dry rock formation. Install the rocks that have fractured to seepage experimental instrument and then inject different temperature fluid with a high-pressure pump. Build a thermodynamic experimental system between hot dry rock fracture and the fluid mutual effect of heat transfer. Use the orthogonal experimental method to test thermo physical parameters, when fluid flowing through fracture network of hot dry rocks under different temperature, pressure and flow conditions, to reveal the heat transfer mechanism in Gonghe basin of hot dry rock artificial fractures and fluid. Establish a coupling model of heat effect between the hot dry rock artificial fracture characteristics, thermal conductivity of rocks, and thermal conductivity of fluid, fluid pressure and flow rate in Gonghe basin by inversion theory. Lay the theoretical foundation for the exploitation of Gonghe basin hot dry rock geothermal system well spacing, fluid injection pressure, injection flow and ground power system installed capacity design.And lay the theoretical for the accurate assessment of recoverable reserves, the optimization of geothermal system parameters and economic evaluation in Gonghe basin.

准确测试干热岩人工裂隙与流体之间的传热特性是设计干热岩地热系统的重要依据，现场试验不仅成本高且由于地质条件不同其结果缺乏普遍适用性，数值模拟尽管简便易行，但需要实验数据验证。选取共和盆地干热岩储层岩心和露头岩石，运用相似理论仿真建造干热岩地热开采人工裂隙，采用注入不同温度、流速及流量的高压流体，进行高保真干热岩裂隙与流体相互作用的传热机理研究。重点采用正交实验法测试不同温压流速及流量的流体流经不同干热岩人工裂隙特征网时流体与岩体的传热特性，揭示共和盆地储层干热岩人工裂隙与流体的传热机理，结合数值模拟，建立共和盆地储层干热岩人工裂隙特征、岩石热导率、流体热导率、流体压力与流速等多参数耦合的热能效应模型，为共和盆地干热岩可采储量的准确评估、地热系统开采参数优化及经济性评价奠定理论基础，为共和盆地干热岩地热开采系统井间距、流体注入压力、注入流量及地面发电系统装机容量的设计提供理论依据。

课题以花岗岩干热岩为研究对象，对研究区干热岩的矿物成分组成进行分析，通过室内实验等对高温作用下岩石的热物理特性进行了研究，包括岩石在高温遇水冷却和水化学损伤作用下的岩石力学及物理特性。通过扫描实验和声发射实验揭示了微观裂隙扩展机理，提出了利用二氧化碳建造干热岩储层裂隙的技术方法及可行性分析。对人工粗糙裂隙进行了表征，研究了人工粗糙裂隙与流体间的换热机理。建立了矿场尺度三维EGS数值模型，对EGS系统产热性能进行了评估。通过本项目的研究工作，取得的主要成果有：建立了基于岩石矿物成分组成的导热性数学模型；建立了岩石遇水冷却下金刚石钻头可钻性数学模型和水化学作用下的岩石损伤模型；提出了二氧化碳爆破建造储层的方法，从微观揭示裂隙扩展规律。通过表征人工粗糙裂隙揭示了粗糙裂隙换热机理；分别探讨了双水平井均匀多孔介质和双水平井平行多裂隙数值模型的换热特性，对换热流体及岩石参数包括流速、注入温度、导热系数、裂隙宽度、裂隙间距、井距以及储层渗透率等进行了敏感性分析，评价了EGS系统的换热特性。相关研究结果可为实际工程提供理论依据和经验。