Particle migration and blockage in geothermal reservoirs during water reinjection: Laboratory experiment and reaction kinetic model

摘要

During water reinjection in geothermal reservoirs, the risk of particle migration and blockage is often unavoidable, especially in the reservoirs with high mud content and poor consolidation. In this paper, a series of core flooding experiments using a sand-packed tube were conducted to evaluate the effects of water flow rate, sand grain composition, temperature, and confining pressure on the particle migration and blockage in reservoir. A novel reaction kinetic model was established to describe the process of particle migration and blockage in porous media. The results show that the movable particles in reservoir can be divided into fine particles (size<1/5 pore throat) and coarse particles (size between 1/5-1/2 pore throat), which can start to migrate successively as water flow rate increases. The fine particles can be produced out, while the coarse particles are likely to block the pore throat, making the permeability fluctuated and eventually decreased. The increase of coarse particle content, temperature and confining pressure can enhance the particle blockage risk in reservoir due to the great decline of the absolute permeability. The established reaction kinetic model of particle migration and blockage can be used to study the rock-fluid interactions during the geothermal water production and reinjection.