Preparation And Performance Research Of Downhole Control-release Corrosion And Scale Inhibitors

At present,the exploitation of most oil fields in China has entered the middle and late stages,and a large amount of water injection is used to maintain reservoir pressure and ensure production.The produced fluid is rich in various corrosive substances and scale-forming ions,which will cause scale and corrosion in oil mining equipments and pipelines,which seriously endangers the normal production of the oil field.In this paper,two water samples collected from an oil field in China were analyzed,and the results demonstrated that the produced fluid in this oil field had a serious calcium carbonate scaling tendency.In order to alleviate the problem of corrosion and scaling of the oil field,solid sodium silicate was used as a control-release material,and various active ingredients were added into reacted and clarified under high temperature conditions to obtain a water treatment agent which could be slowly released in the produced fluid of oilfield and play the role of corrosion and scale inhibitionBy referring to relevant literature,the technical conditions for sample preparation process and formula of the control-release corrosion and scale inhibitor sample were optimized by experiments.When the modulus of the sample was 1.8 and the dosage of the auxiliary M was 15wt.%and the other agents,such as ZnO and Al₂O₃ are added with the proper amount,the reaction was carried out under 900°C firstly,and then the reacting mixture was clarified under 1200°C for 3 hours,finally,it was cooled to room temperature to get the required water treatment agent.At 50°C,the dissolution rate of water treatment agent was 14.57mg·cm^-2·d^-1 in the produced fluid,and its dissolution period was as long as 314 days.When the concentration of the water treatment agent in the produced fluid was 30mg·L^-1,the scale inhibition rate of the water treatment agent to the two produced fluids reached 96.1%and 95.8%,respectively,and its corrosion inhibition rate was 46.1%.Five tests for the scale-up molding of the water treatment agent were carried out according to the formula of the water treatment agent determined by laboratory experiments.And the technical conditions for the preparation process and the formula which was benefit to the industrial production of the water treatment agent were determined.Performance evaluations for the industrially scale-up water treatment agent were performed,and the evaluation results were basically consistent with laboratory results.The raw materials used to the preparation of the control-release corrosion and scale inhibitors in this paper are wide in source and lower in cost,and it could be prepared into required shapes according to the different applications.It was not necessary to set up the additional injection equipment for the control-release corrosion and scale inhibitor proposed by this work,and its action period was longer.All the characteristics of the control-release corrosion and scale inhibitor proposed by this work could save equipment investment and operating cost for the oil mining equipments and pipelines in targeted oil field.Therefore,it could be applied to the targeted oil field.Since the control-release corrosion and scale inhibitor proposed by this work had a certain ability to adapt to the change of environmental factors,such as temperature and p H,it is expected to be used in corrosion and scale inhibition of other water system.