Study On Corrosion & Scaling Situation Of Offshore Oil Water Injection System And Its Control Technique

ShengLi oilfield has entered development of water-flooding oilfield stage. In recent years, changes in the composition and properties of oilfield reinjection water caused many problems such as string corrosion, pipeline and formation scale, which have great influence on the productivity of oilfields. In this paper, the main types of corrosion is ferrous carbonate, the main types of scaling is dolomite through XRD analysis. With weight-loss method, the main factors of corrosion rate such as temperature, dissolved oxygen and compatibility were confirmed. The results of the test showed that the corrosion rate changed with temperature in the form of a parabola, and the highest corrosion rate corresponded a temperature range(50-60℃). The corrosion rate of increased with the increase of dissolved oxygen. Different kinds of reinjection water mixed by reasonable compatibility ratio can inhibit the corrosion to some degree. In addition, it was deduced that these three factors jointly affect the corrosion rate of coupon evidently.By electrochemical methods of metal corrosion, the corrosion process of coupon in three water samples controlled by the cathodic under the site temperature(50℃). The type of corrosion in the well water and produced water was dominantly localized corrosion, rather than general corrosion in sea water. The pitting corrosion reaction resistance in produced water was greater than in well water(5.256E10>>195.4), therefore, coupon corrosion rate in produced water was smaller.By single-factor experiment, suitable site HSJ corrosive inhibitors were synthesized in laboratory. The corrosion rate of coupon in different samples of water could be limited under the standard (0.076 mm·a^-1) range. The inhibiting corrosion capability of HSJ was prior to the inhibitor which was used in oil region and commercial corrosive inhibitors, the serious problem of corrosion was expected to solve. The inhibiting corrosion capability of different concentrations HSJ is investigated, the results showed that the HSJ adsorption in the steel conformed Langmuir rules, having both physical adsorption of chemical adsorption.With static simulation tests, the factors of scaling process and degree were confirmed. The results indicated that with temperature increased the scaling degree were exacerbated, and the non-compatibility of reinjection water was also an important factor in scaling. On this basis, a squeezing adsorptive scale inhibitor (HCD-1) was synthesized in laboratory, the scale inhibition effect of HCD-1 was attested to be good on source water and sea water- source water- produced water complex systems, and the optimal concentration of HCD-1 was ranged from 20 mg·L^-1 to 60 mg·L^-1.