Study Of Oilfield’s Water Treatment Agents For Injection Pipes

At present,water-flooding exploitation is the common method of domestic oilfields.The re-injection of water produced by oil wells into the formation can not only achieve the effects of water flooding enhancing production,but also meet environmental protection requirements.The study area is a typical oil blocks,whose characteristics inculuding low oil yielding,high fluid yield and high water cut.It also take water-flooding exploitation as the main development method by using 20#carbon steel pipes,however,the severe corrosion of the water injection pipe is a critical problem.Therefore,this article takes it as research content that exploring how to prevent and alleviate the corrosion of water injection pipelines in oil blocks,and takes finding the most suitable water treatment agents for this area as the target.For this purpose,the following research has been carried out.First of all,the produced water samples from 15 oil Wells in different areas of the study oil blocks and the gas ingredients were analyzed,information we obtained that the produced water was mainly weakly acidic and alkaline with high concentration of HCO₃^-、Cl^-,and CO₂and H₂S accompanied.Secondly,through using the combination method of laboratory test analysis and practical test research,and taking weightlessness and corrosion product analysis as evaluation methods,the corrosion effects of different main ions,temperature and pH value of water were analyzed.Its consequence is that injection-water temperature,the concentration of HCO₃^-and Cl^-,pH value have an evident influence on water injection pipes’corrosion.With the growth of temperature and the concentration of HCO₃^-,the corrosion of water injection pipes accelerated.With the increase of the concentration of Cl^-,and the corrosion rate of water injection pipes increased at first then decreased.With the increase of pH value,the corrosion rate decreased.Finally,according to the analysis of the main indicators of corrosion evaluation before and after the addition of water treatment agents the anticorrosion effect of water treatment agent on water injection pipes is estimated.It is concluded that three water treatment agents,CT-2 UT2-2 YC-2,have perfect corrosion inhibition effect on water injection pipes,UT2-2 has the best corrosion inhibition effect and applicability among those corrosion inhibitors.On the basis of research results,the main anti-corrosion countermeasures in the study area are as follows:The compound of UT2-2 water treatment agent is preferred.Specific water treatment agents should be selected in different areas to reduce the concentration of Cl^-,HCO₃^-,Ca²⁺,Mg²⁺ions and improve the pH value of the injected water.At the same time,appropriately increasing the temperature of injected water is beneficial to alleviate the corrosion of the water injection pipeline in the study area.And it is also important that monitoring the ingredients of injected water regularly and adjust the ratio of water treatment agents in time.