A Study Of Dynamic Scaling Property Evaluation Method For Oilfield

With the oilfields development of our country,the technology of wastewater reinjection and mixed injection of multilayer produced water has been widely used.Because of the change of water quality,the amount of scaling becomes an important control index in the process of sewage treatment and reinjection.The scale prediction model is used to analyze the scaling properties of oilfield sewage,however,the prediction results are different from the actual sewage scaling properties.At the same time,because the scaling amount of sewage has a long measuring period and is affected by the adsorption of the vessel wall,it has a certain influence on the rapid determination of the fouling amount and the evaluation of the water quality stability.Therefore,It is of great practical significance to develop a set of rapid measurement method for scaling quantity of oil field water injection.In this paper,the adsorption properties of four kinds of filling materials,such as cellucotton,sponge,retinervus luffae fructus and gauze,for calcium sulfate scaling were detailedly studied by static and dynamic oscillation experiments.The effects of flow rate,temperature and adsorption time on the measurement results of scaling amount were investigated by using a self-made dynamic experimental device.The measurement accuracy of the developed method was analyzed by using chitosan modified clay as the adsorbent for the determination of scaling.Finally,a combined method of scaling removal for mixed water samples was established.The results show that under the static experimental conditions,the adsorption capacity of cellucotton(per gram)was the highest,and reaching 0.97 g/g.The dynamic oscillatory experiment shows that the adsorption capacity of cellucotton(per gram)is large and the adsorption effect is stable under various conditions,reaching 0.72 g/g.The self-made dynamic experimental device consists of packing pipe,sewage circulation system and heating system.when the initial concentration of the scaling in the simulated water is lower and the contact time is 2 h,the adsorption rate of cellucotton for the scaling can reach 98%.When the experimental temperature is 50 C,the adsorption rate of cellucotton for the scaling is the highest and can reach 99%.The adsorption capacity of cellucotton(per gram)for the scaling is up to 0.96 g/g at the experimental temperature of 40?.When the flow rate of 60 L/h,the adsorption rate of cellucotton for the scaling is the highest.Moreover,when the flow rate of 100 L/h,the adsorption capacity of cellucotton(per gram)for the scaling is the highest and can reach 1.30 g/g.Evaluating the descaling of actual wastewater by adsorption method,and then according to the volume ratio of 1:0.3 for three phase separation and formation water mixed,the experimental results show that the scaling quality of mixed water samples is 94 mg/L.In the flocculation process,when the pH value is 7-7.5,PAC added amount is 80 mg/L,the dosage of PAM is 3 mg/L,after the first step in using cellucotton to adsorption,the second adsorption were conducted by the suspension with chitosan modified clay(the modified soil dosage is 500 mg/L),the scaling quality after adsorption is 3 mg/L.