关键词: 增强型地热系统, 干热岩, 高温遇水冷却, 注采参数, 物理力学特征, 波动特征

Abstract: In order to investigate the impacts of injection-production parameters on physico-mechanical and wave characteristics of hot dry rocks (HDR) in Songliao Basin, a uniaxial compressive test and wave velocity tests of longitudinal and shear waves of granite after high temperature treatments with subsequent water cooling under different injection-production conditions were performed. Considering the relationships between various injection-production parameters (rock sample temperature, water temperature, and cycles of high temperature with water) and granite physico-mechanical characteristics (shape, peak intensity, elastic modulus, and Poisson's ratio), and wave characteristics (longitudinal and shear wave velocity), we established the fitting curves of mechanical characteristics and wave characteristics under different injection-production conditions. Moreover, the variations of physico-mechanical and wave characteristics of granite under different rock sample temperatures and different water temperatures during the shelving process were studied. The results show that: (1) at the initial stage of shelving process, the higher the temperature of the rock sample was, the greater the magnitude of decrease in mass, longitudinal and shear wave velocity and elastic modulus can be. With increasing water temperature, the magnitude of decrease in mass, longitudinal and shear wave velocity, and elastic modulus first show an increase and subsequently a decrease; (2) among the injection and production parameters of the rock mass physical mechanics and wave characteristics on the temperature of the target area, parameters with the degree of influence from high to low are the target area temperature, the number of water injection cycles, and the water injection temperature. With the increase in the temperature of rock samples and cycles of high temperature with water, both the mechanical and wave characteristics of granite gradually decreased; while their variations can be opposite when the water injection temperature increases. After the treatment at the high temperature of 600℃ , the longitudinal wave velocity, shear wave velocity, peak intensity and elastic modulus of granite decreased by 53.44% , 58.02% , 66.56% , 79.84% , respectively. After 5 cycles of high temperature and water cooling treatments, the longitudinal wave velocity, shear wave velocity, peak intensity and elastic modulus of granite decreased by 33.61% , 33.63% , 34.22% , 56.00% , respectively. (3) The injection-production
parameters that affect the correlation between granite mechanics and wave characteristics, with the extent from large to small, are the temperature of the rock samples, cycle numbers of high temperature with water, and the water temperature. This study provides a useful reference for selecting injection-production parameters on thermal extraction in Songliao Basin.

Key words: enhanced geothermal system, hot dry rock, high temperature with water cooling, injection-production parameters, physico-mechanical characteristics, wave characteristics