Research On The Corrosion Mechanism And Anti-Corrosion Technology Of Water Injection Pipeline In Yanchang Oilfield

Yanchang Oilfield Co., Ltd. has built22oil production plant,309water injection plant,2302injection wells, the total length of water injection pipelines is400km so far, the formation energy is greatly complated, in order to increase crude oil production and oil recovery, which make a great contribution for normal local crude oil production. According to field investigation in recent years, water produced by the oil field has high salinity and alkaline pH, so oilfield water injection pipeline corrosion situation is extremely serious. With water cut produced gradually rising, the scale of water injection development is increasing and the service life of water injection network is lengthened, corrosion of the water injection line in Yanchang oilfield in recent years has a sharp increased trend, so the problem of water injection pipeline corrosion prevention has become essential. Therefore, to ensure the water injection pipeline in Yanchang oilfield safety and continuous operation and to prolong the life of the pipeline for corrosion protection, clarifying the underlying causes of the corrosion and understanding the corrosion law is studied in this paper.The main research work of this paper is:(1) Corrosion investigation of Yanchang water injection pipeline internal corrosion status and analysis of water injection water quality. Through the survey of AnSai—YongPing water injection pipe sections which are abandoned because of corrosion and conducting on-site excavation, understand the pipeline internal corrosion and anticorrosion technology present situation; Through component analysis of the injection water quality, study the corrosion of water injection water quality.(2) Internal corrosion behavior study of water injection pipeline in PanLong—YongPing section. By interior coupon experiment and electrochemical testing, tubing corrosion resistance are analyzed; And compared with field test data, do the experimental researches on the main factors influencing the corrosion; Work out its regularity of corrosion rate and the changes with temperature, time, etc, and analyze the law. Using the energy spectrum analysis and SEM analysis of the corrosion process of scaling samples, analyzing the main composition of scaling in water injection pipeline and the mechanism of corrosion under the scaling.(3) Internal corrosion behavior research on water velocity of water injection pipeline. By similarity principle, design experiments independently which change speed instead of velocity change is used to study the influence of the velocity to the pipeline corrosion rate, which is used for simulating the scene of theoretical innovation, getting the relationship between velocity and the corrosion rate, results show that the velocity influence on the corrosion rate significantly.(4) Establishment of the mathematical model. On the basis of measured data getting from the experiment, establishing the mathematical model between corrosion rate of water injection pipeline with temperature, time and velocity to preliminary forecast Yanchang pipeline steel corrosion rate when main influent factors changes, and then provide a certain theoretical guidance of corrosion protection work in order to prolong oilfield water injection pipeline under the changing condition of environment.(5) Study of corrosion inhibitor. For water quality characteristics in Yanchang oilfield water injection line, developing the Yanchang oilfield special corrosion inhibitor is a major research contents and key of this paper. To evaluate corrosion control effect of corrosion inhibitors, doing the interior test evaluation with five kinds of corrosion inhibitors which are developed HJF-94, ODD, TC-610, CQ-HO2and LED in the simulation of the oil field production conditions. Determining the optimum dosage of each inhibitor and best corrosion control effect, comparing the five corrosion inhibitors, the results show that the corrosion control effect of TC-610and CQ-HO2is superior to other corrosion inhibitors; At the same time, carrying out the experiment of two kinds of corrosion inhibitors by combination test experiments with different proportion distribution. Results show that effect of using alone the TC-610corrosion inhibitor is much better, and this is a significant technological innovation.(6) Study on measures of internal corrosion protection for YanChang water injection pipeline. On the basis of literature research, the suitable measures of internal corrosion protection for Yanchang oilfield water injection pipeline are recommended.