EGS载热流体水岩作用对人工地热储层裂隙物性特征的影响

Impact of Water/CO_2-Rock Interactions on Formation Physical Properties in EGS

增强型地热系统(EGS)是一种从低渗透率低孔隙度岩层中提取热量的工程。载热流体注入深部地热储层后在储层裂隙发生水岩作用,引起地热储层矿物的溶解和沉淀,改变储层裂隙通道的物性特征,对EGS的长期运行产生重要影响。以苏尔茨地区的一种典型花岗岩为人工地热储层,建立了一维多重相互作用连续统一体地质模型,将相同温度的CO2和水以相同压力注入人工地热储层裂隙通道中,探讨两种载热流体的水岩作用对储层裂隙物性特征的影响。结果表明,在同样的储层状态、相同的运行模式下,CO2-EGS水岩作用对裂隙通道物性特征的影响明显小于H2O-EGS。

The enhanced geothermal system（EGS） is an engineering technique that has been created to extract economical amounts of heat from geothermal resources of low permeability and porosity. After the heat-exchange fluid is injected into the deep geothermal reservoir, there will be a water-rock interaction in the fracture channel, causing the dissolution and precipitation of reservoir minerals and changing the physical properties of the fracture channel, influencing long-time running of EGS significantly. This paper concerns a typical granite in Soultz as a geothermal reservoir and builds up a one-dimensional MINC model. Then CO2and water with identical temperatures and pressures are injected to contrast the effects of injected fluid water/CO2-rock interactions on the fractures in EGS. Results show that the effect of water-rock interaction of CO2-EGS on fracture channel properties is less obvious than that of H2OEGS on the same operation mode.