干热岩作为一种可再生能源，因储量大、无污染等优点成为国内外开发的重点。建立增强型地热系统（Enhanced Geothermal Systems，简称EGS）是高效开发利用地热的最有效方法。干热岩热储层中裂隙的渗透性、连通性是评价EGS的标准，水力压裂是增强裂隙特性的重要手段。为了掌握水力压裂时裂缝的扩展规律及储层的产热性能，本文以青海共和盆地恰卜恰地区GR1地热井3500 m-3705 m深度段为研究对象，开展了干热岩热储层水力压裂裂缝扩展规律及产热性能的模拟研究。

通过查阅资料，总结青海共和盆地干热岩资源概况，重点分析恰卜恰地区干热岩的成因和GR1地热井3500 m-3705 m的温度和天然裂隙特征。基于全局插入Cohesive单元的方法，建立含有天然裂缝的二维水力压裂模型，重点模拟了储层基质的弹性模量、抗拉强度、压裂液排量和水平地应力差对水力裂缝扩展的影响。通过PYTHON编程对ABAQUS的后处理进行二次开发，提取了模型中破裂单元坐标、裂缝长度和宽度等数据，确定了不同变量对水力裂缝长度和宽度的影响强度和影响范围。

将预置裂缝与最大水平主应力方向、裂缝扩展方向的夹角分别定义为射孔角和裂缝偏转角，模拟研究水力裂缝在不同水平地应力差和不同射孔角度下的扩展情况。通过提取并分析水力裂缝长度和宽度等数据，发现了射孔角度对水力裂缝偏转角及扩展形态的影响规律。

建立了含有两条预制裂缝的水力压裂模型，通过控制裂缝间距，模拟研究了两条裂缝同时压裂或分时压裂对裂缝扩展形态的影响。通过提取水力裂缝长度和宽度等数据，分析了不同起裂方式对水力裂缝长度和宽度的影响，总结了两条裂缝分时压裂时不同阶段间的相互影响规律，确定了水力裂缝扩展时几乎不受起裂方式影响的最小间距为30m。

建立了二维单裂缝热流固耦合模型，模拟研究了裂缝间距、裂缝宽度、换热介质种类和换热介质流速对储层热输出功率和电输出功率的影响。通过分析不同变量对裂缝出口流体温度、热输出功率、电输出功率及运行年限的影响情况，得到了裂缝间距、裂缝宽度和换热介质流速对储层产热性能的影响规律；通过对比超临界二氧化碳（Supercritical Carbon Dioxide，简称SCO₂）和水（H₂O）这两种换热介质在运行年限内的总电输出功率，确定了SCO₂作为换热介质的优势。

As a kind of renewable energy, hot dry rock has become the focus of domestic and international development due to its large storage capacity and non-polluting advantages. Establishing Enhanced Geothermal Systems (EGS) is the most effective way to develop and utilize geothermal energy efficiently. The permeability and connectivity of the fractures in hot  dry rock reservoirs are the criteria for evaluating EGS, and hydraulic fracturing is an important means to enhance the fracture characteristics. In order to grasp the fracture expansion law and the heat production performance of the reservoir during hydraulic fracturing, this paper takes the 3500 m-3705 m depth section of the GR1 geothermal well in the Chabcha area of the Qinghai Republican Basin as the research object and conducts a study on the fracture expansion pattern and heat production performance of dry thermal rock thermal reservoir.

By reviewing the data, this paper summarizes the overview of dry heat rock resources in the Republican Basin of Qinghai, focusing on the genesis of dry heat rock in the Chabcha area and the temperature and natural fracture characteristics of the GR1 geothermal well 3500 m-3705 m. Based on the global insertion of Cohesive units, a two-dimensional hydraulic fracture model containing natural fractures is established, focusing on simulating the effects of elastic modulus, tensile strength, fracturing fluid discharge and horizontal ground stress difference of the reservoir matrix on hydraulic fracture extension. The data of fracture unit coordinates, fracture length and width in the model were extracted by secondary development of ABAQUS post-processing through PYTHON programming, and the intensity and range of influence of different variables on hydraulic fracture length and width were determined.

The angle between the preset fracture and the direction of the maximum horizontal principal stress and the fracture expansion direction are defined as the perforating angle and the fracture deflection angle, respectively, to simulate and study the expansion of the hydraulic fracture under different horizontal ground stress differences and different perforating angles. By extracting and analyzing the data such as hydraulic fracture length and width, the influence law of the injection hole angle on the deflection angle and expansion pattern of hydraulic fracture is found.

A hydraulic fracturing model containing two prefabricated fractures was established, and the effects of simultaneous fracturing or split-time fracturing of two fractures on the fracture expansion pattern were simulated and studied by controlling the fracture spacing. By extracting the data of hydraulic fracture length and width, the influence of different fracture initiation methods on the hydraulic fracture length and width was analyzed, and the law of mutual influence between different stages when two fractures were fractured in split time was summarized, and the minimum spacing of 30m that was almost independent of the fracture initiation method was determined for the hydraulic fracture expansion.

A two-dimensional single fracture heat-fluid-solid coupling model was established, and the effects of fracture spacing, fracture width, heat transfer medium type and heat transfer medium flow rate on the reservoir heat output power and electrical output power were simulated and studied. By analyzing the effects of different variables on the fracture outlet fluid temperature, thermal output power, electrical output power and operating life, the effects of fracture spacing, fracture width and heat transfer medium flow rate on the heat production performance of the reservoir were obtained; by comparing the effects of two heat transfer media, supercritical carbon dioxide (SCO₂) and water (H₂O), on the thermal output power and electrical output power of the reservoir during the operating life of the fracture. The advantages of SCO₂ as a heat transfer medium were determined by comparing the total electrical output of the two heat transfer media, Supercritical Carbon Dioxide (SCO₂) and water (H₂O), over the operating life.