Research On Scaling Corrosion Kinetic Law Of Reinjection Water Pipeline In Gas Field

In the process of gas field development,due to the characteristics of production processes such as hydraulic fracturing and gas extraction,reinjection is required.The quality of the refilled water is unstable and the composition is more complex,which is likely to cause scale and corrosion of the pipeline.Based on the kinetic equation,this paper carried out a laboratory simulation of scaling experiment,established a mathematical model for three common types of scale(calcium carbonate,calcium sulfate,barium sulfate),fitted the kinetic parameters,and carried out the actual pipeline Modeling.Predict the thickness of pipe fouling.At the same time,an electrochemical corrosion test was carried out,and a single-factor experimental system was used to study the influence of temperature,pH,Cl-,SO42-,Ca2+,HCO3-,etc.on corrosion,which has a greater impact.It is of great significance to predict and prevent scaling in gas field production.Corrosion electrochemical experiments show that temperature has a significant effect on the corrosion rate.Increasing temperature will greatly promote the occurrence of corrosion.The pH value can affect the cathodic corrosion reaction,and hydrogen release corrosion is the main cause under acidic conditions.Increased alkalinity will inhibit hydrogen evolution and corrosion.Oxygen absorption corrosion always occurs;the main effect of Ca2+ and HCO3-on corrosion is to promote low concentration,and the formation of high concentration calcium carbonate can prevent corrosion from occurring.Both Cl-and SO42-will promote the occurrence of corrosion,while too high a concentration will inhibit the corrosion rate on the contrary.Finally,the pipeline corrosion process is analyzed and summarized.The study found that the higher the concentration of fouling ions,the greater the amount of fouling.Ion concentration mainly affects the degree of supersaturation,which is the driving force that affects the fouling rate.Therefore,increasing the ion concentration can also accelerate the fouling reaction.Among the three types of scale,when the ion concentration is the same,barium sulfate has the most scale,followed by calcium carbonate,which is mainly related to its solubility.In the temperature experiment,it can be seen that increasing the temperature can effectively reduce the time required to reach the maximum fouling amount,because the temperature can accelerate the reaction speed.Temperature has the greatest effect on calcium carbonate scaling,and its solubility decreases with increasing temperature.Therefore,the scale amount increases with the increase of temperature,while the scale amount of barium sulfate is less affected by temperature.The second-order reaction rate equation of the concentration experiment was fitted,and the results showed that the reaction rate and the scaling amount both fit the second-order reaction rate equation,and the rate constant did not change with the change of ion concentration.By fitting the temperature kinetic experiment,the kinetic parameters of three kinds of scale can be obtained.The kinetic parameters obtained were used to establish a calcium carbonate scaling kinetic model to simulate the scaling of calcium carbonate in a vertical wellbore for modeling.The main influencing factors are pH,pressure,ion concentration and temperature.Calculate the scaling of calcium carbonate with the depth of the borehole.Distribution and variation of ruler thickness.