Simulating Study On Fixed-point Scale Removal Of Barium Sulfate Scale Based On Shallow Pool Theory

In recent years,as the major oil fields in China have entered the late stage of mining,the comprehensive water content has risen and the scaling problem is serious.The scale-causing substances mainly include carbonate scale and sulfate scale,and the sulfate scale has the characteristics of small solubility product,compact structure and high hardness,which is difficult to treat.Physical anti-scaling methods such as ultrasound,magnetic field and high frequency electric field have been used in oilfields,but these methods have been found to be ineffective,costly and limited in field application.For this reason,according to the shallow pool theory in water treatment industry,a physical stagnant point descaling device has been developed,which passes the fixed point descaling device before the mixed production of different formations and different wells before entering the manifold.The sulphate scale is deposited to achieve the purpose of preventing scale deposition in the subsequent gathering pipeline.This thesis mainly uses the device to study the influence of external factors such as reaction time,initial concentration of scaled ions,molar concentration ratio and temperature on the scale of barium sulfate;The numerical simulation study was carried out with Fluent software.The effects of internal device structure factors,such as inclined plate angle,inclined plate length and inclined plate spacing,on barium sulfate scale removal rate were analyzed.By analyzing the influence of structural parameters on the volume fraction distribution of barium sulfate particles,the flow field distribution in the model device,the change of turbulent kinetic energy of fluid in the device and the volume fraction of solid particles at the outlet of the device,the optimal structure size of the fixed-point scale removal device was selected with the removal rate as the index.The experimental results show that the optimum fouling time of barium sulfate in the fixed-point cleaner is 5-10 min.When the concentration of barium ion is 742 mg/L,it is the best condition for the formation of barium sulfate.the maximum scaling rate of barium sulfate is 1:4 of the molar concentration ratio of barium ion to sulfate ion,and the most easily scaling rate of barium sulfate is determined when the temperature is 50°C.Based on the above experimental conditions,the scaling rate of fixed-point descaler to barium sulfate is more than90%.When the angle of inclined plate is 60 degrees,the length of inclined plate is 100 mm,and the spacing of inclined plate is 11.06 mm,the internal structure size of fixed-point descaler model is the best choice.