Clogging Mechanism And Prevention Measures Research Of Geothermal Water Reinjection

Artificial reinjection is the necessary way to realize sustainable recycling of geothermal energyresources and water resources, but clogging is the bottleneck problem of artificial reinjection. We musthave breaks in reinjection clogging mechanism if we want to achieve the purpose of recycling. Howeverclogging mechanism of groundwater especially geothermal water recharge, which due to complexity andvariability of factors. In this paper we take geopressed reservoir recharge of national geothermal cityXianyang for example, we analysed clogging mechanism of geothermal water recharge based on Coremineral and physical property analysis, SS Particle size characteristics and its mineral analysis, simulatedexperiment, PHREEQC simulation, Water quality comparison of reinjection from beginning to end, gas andmicrobial analysis, evidence on the ground and so on. Discussed every influence factor of clogging andspace-time varying pattern of clogging extent to study clogging mechanism of inrejection process. And thenprovide theory basis for preventing clogging of Xianyang urban area. Furthermore, try to provide researchideas and reference for geopressed reservoir injection.The study result show, primary clogging factors include physical clogging, chemical clogging, gasclogging, microorganism clogging and complex clogging in study area. Physical clogging mainly arousedfrom SS clogging, particle migration and viscous particle inflation. The permeability of core decreasedsharply when simulated experiment begin, and then decreased slowly. The clogging extent increased whentemperature rise, clogging extent in dielectric surface is more serious than internal part. The safety velocityare0.75ml/min and4ml/min respectively of core A and B, in view of safety velocity we calculated themaximum velocity of every well in study area. The permeability of core has not been great changes afterused water of different TDS injected, so viscous particle inflation caused clogging extent is not obvious.In this paper, software named PHREER was used to simulate mine dissolution and precipitationtendency during the process of thermal reservoir–extraction well–hot water transportation pipe–injectionwell. Combined with the research results of indoor reinjection experiments and field sampling, it isconclude that different scaling could appear during different processes of geothermal water extraction,transportation and reinjection as the environment change. The important thing is calcite scaling formed inall the processes. Gas clogging aggravates as the temperature and pressure of the water increasing,microorganism clogging is mainly caused by saprophytic bacteria, iron bacteria and sulfate reducing bacteria. Moreover, compound clogging mechanism is also analyzed in the paper. Compound cloggingcharacterized by chemical, microorganism, physics mixing clogging exists in the reinjection well while thecompound clogging characterized by chemical, physics, gas mixing clogging forms in the thermal reservoir.All the studies results indict that the clogging types in the area are particle migration, chemical clogging,suspended clogging, gas clogging, and clay particle expand respectively in descending order.At the end of the paper, for every type of clogging and compound clogging, relevant prevention anddescaling measures were put forward. In somewhat way, there could be some lacks in the ways ofreinjection clogging mechanism study in this paper, so more suggestions were also proposed in the paper.