Study of the physical clogging mechanism of sandstone geothermal tailwater recharge

An important part of geothermal development is the re-injection of waste geothermal fluids into the reservoir, which can extend the life of the geothermal resource. However, the difficulty of recharge and the clogging problem in the recharge process are still a worldwide problem that restricts the sustainable development and utilization of sandstone geothermal reservoirs. The main factor affecting the recharge effect is physical clogging. In this paper, a series of simulation experiments were conducted to study the physical clogging in the recharge process of sandstone thermal storage in the Lubei area, which conclude that the degree of clogging is related to the particle size and concentration of suspended matter. At a certain particle size, the clogging is most serious when the experimental suspended matter concentration gradient is up to 140 mg/L. In addition, particle migration in clogging is related to the recharge flow rate, and the critical flow rate is 0.75–2 mL/min, which is experimentally derived, and it is recommended that the recharge rate should be controlled below 0.75 mL/min during the actual recharge. This paper provides a scientific basis for the efficient recharge of geothermal tailwater through the study of the clogging mechanism.