Experimental Study And Mechanism Analysis Of Geothermal Water Scaling Inhibition

With the development of clean energy in many countries around the world,geothermal energy is becoming more and more popular.Based on the huge application background of geothermal energy resources in the field of power generation and direct utilization,we systematically studied scaling in pipelines and underground reservoirs by experimental methods.Based on the dynamic scaling trend analysis system of geothermal water and the multi-function displacement device,the scaling and scaling inhibition simulation experiments of pipelines and underground reservoirs are carried out.The scaling trend and the scaling inhibition effect of scaling inhibitions are studied by using hydrochemical analysis method,XRD instrument and Micro-CT and so on.It provides some theoretical and technological support for the efficient development and application of geothermal resources.The main conclusions are as follows:?1?The hydrochemistry and physical property analysis of geothermal water shows that the geothermal water type is NaHCO₃,and the Larson index?LI?to determine the geothermal water for scaling type fluid,scaling degree is slight.The content of CaCO₃in the scaling is more than 99%,and the scaling sample is completely dissolved in 5%hydrochloric acid solution.It can be considered that the scaling is mainly composed by calcium carbonate.The internal structure of scaling is loose,and there are many gaps.The gap inside the scaling increases obviously after adding scaling inhibitor,indicating that adding scaling inhibitor has obvious effect.The scaling of geothermal water is due to the change of pressure and temperature in the process of exploitation and utilization,and the solubility of calcium ion in geothermal water is changed.?2?The experiment of dynamic scaling trend analysis of geothermal water shows that PASP,PESA and HPMA three inhibitors have inhibition effects.At 90?and inhibitor concentration is 15 mg/L,after 8 h,the PASP inhibition rate is 91.27%,PESA is 90.09%,HPMA is 83.67%.Therefore,the scaling inhibition performance of PASP scaling inhibitor is better than PESA scaling inhibitor,PESA scaling inhibitor is better than HPMA.And PASP and PESA are easy to degrade scaling inhibitor,HPMA is a biodegradable scaling inhibitor,the biodegradability of PASP and PESA is obviously better than HPMA.?3?The experimental results of coreflooding of geothermal water shows that by using 10,20,40 mg/L,three kinds of displacing water at different calcium ions are tested.The core blockage rates of the cores are 13.1%,15.6%and 17.5%respectively without the scaling inhibitor,and the core blockage rates are 12.5%,14.2%and 15.4%respectively after the addition of scaling inhibitors.With the increase of calcium ion concentration in displacement water,the blockage rate also increases.After analyzing the composition of core blockage,the main material of geothermal reinjection water clogging is carbonate,which easily blocks core pores and conveying pipes,and seriously affects the recharge efficiency of reinjection water.As the main blockage material is carbonate,the PESA scaling inhibitor can play a very good role in alleviating it.