Control of Geothermal Reservoirs Consisting of Multiple Cracks

本项目的主要目标是阐明在具有许多薄弱面的岩体中地热工程储层（如HDR/HWR储层）的力学响应。为此，我们已经建立了模型的情况下，水库由无数的关节和水库的情况下，由主要的水库裂缝。阐明了此类储层的基本特征。然后，我们成功地将其应用于在芬顿山HDR油田和汤森HWR油田进行的大规模水力压裂/增产的结果。优选地，可以通过使用从钻孔深度取回的岩心样品内的裂缝的破裂表面的几何和力学特性来估计模型的基本特性。因此，我们在实验室研究的基础上，提出了利用裂隙表面分形特征估算裂隙水力特性的新方法。 ...更多信息 三轴应力条件下的ry实验。此外，我们进行了小型水力压裂在一个巷道在神冈矿，使一个人工裂缝和表征的分形特征的表面水力压裂所产生的发现，分形特征不同于那些由爆炸所产生的裂缝表面和slideside的表面，这是受到剪切运动。我们还开发了井间地震测量、钻孔雷达测量和精密声发射测量等新技术，用于估计多裂缝地热储层的结构和围岩的原地应力状态。我们分析了在地热田观测到的数据集，并利用这些新技术估计了储层特征。结果表明，储层裂缝中很可能存在多条或多条小的次生裂缝。采用立方体填充床模拟含二次裂隙的岩石，通过室内实验研究了含二次裂隙的储层裂隙的水力和传热特性。少

The main objective of the present project is to clarify the mechanical response of geothermal engineered reservoirs, such as HDR/HWR reservoirs, within a rock mass with many planes of weakness. To this end, we have constructed models for the case that the reservoir consists of innumerable joints and for the case that the reservoir consists of predominant reservoir cracks. We have clarified the basic characteristics of such reservoirs. Then, we have applied them successfully to the results of massive hydraulic fracturing/stimulation conducted at the Fenton Hill HDR field and at the Yunomori HWR field. It is preferable that the basic characteristics of the models can be estimated by using the geometrical and mechanical characteristics of fracture surfaces of fractures within core samples retrieved from the depth of boreholes. Therefore, we developed new methods for estimating the hydraulic properties of fractures from the fractal characteristics of fracture surfaces based on the laborato … More ry experiments under tri-axial stress conditions. Furthermore, we conducted mini-hydraulic fracturings in a driftway at the Kamioka mine to make a man-made fracture and to characterize the fractal characteristics of the surfaces created by hydraulic fracturing to find that the fractal characteristics are different from those of surfaces of fractures made by explosion and of slicken sides which are the surfaces subjected to shear movements. We have also developed new techniques on crosshole seismic measurement, borehole radar measurement and precise AE measurement for estimating the structure of multicrack geothermal reservoirs and the in-situ stress state of surrounding rocks. We have analyzed data sets observed at geothermal fields and have estimated reservoir characteristics by using these new techniques. It was found that it is highly probable that man-made reservoir cracks are accompanied by many-small secondary cracks generally. The hydraulic and heat transfer properties have been investigated for reservoir cracks accompanied by the secondary cracks by conducting laboratory experiments, where the rock with secondary cracks is simulated by a packed cube bed. Less